Inequality in disease

From Wikipedia, the free encyclopedia

Social epidemiology focuses on the patterns in morbidity and mortality rates that emerge as a result of social characteristics. While an individual's lifestyle choices or family history may place him or her at an increased risk for developing certain illnesses, there are social inequalities in health that cannot be explained by individual factors. Variations in health outcomes in the United States are attributed to several social characteristics, such as gender, race, socioeconomic status, the environment, and educational attainment. Inequalities in any or all of these social categories can contribute to health disparities, with some groups placed at an increased risk for acquiring chronic diseases than others.

For example, cardiovascular disease is the leading cause of death in the United States, followed closely by cancer, with the fifth most deadly being diabetes. The general risk factors associated with these diseases include obesity and poor diet, tobacco and alcohol use, physical inactivity, and access to medical care and health information. Although it may seem that many these risk factors arise solely from individual health choices, such a view neglects the structural patterns in the choices that individuals make. Consequently, a person's likelihood for developing heart disease, cancer, or diabetes is in part correlated with social factors. Among all racial groups, individuals who are impoverished or low income, have lower levels of educational attainment, and/or live in lower-income neighborhoods are all more likely to develop chronic diseases, such as heart disease, cancer, and diabetes.

Gender

In the United States and Europe, up until the 19th century, women tended to die at an earlier age than men. This was largely due to the risks involved in pregnancy and childbirth. However, in the late 19th century there was a shift in life expectancy and women started to live longer than men. Notably, this is partly explained by biological factors. For instance, there is a cross-cultural trend that male fetal mortality rates are higher than female fetal mortality rates. Additionally, estrogen decreases the risk of females acquiring heart disease by lowering the amount of cholesterol in the blood, while testosterone suppresses the immune system in males and puts them at risk for acquiring serious illnesses. However, biological differences do not fully account for the large gender gap in the health outcomes of men and women. Social factors play a large role in gender disparities in health.

One of the main factors that contributes to the decreased life expectancy of males is their propensity to engage in risk-taking behaviors. Some commonly cited examples include heavy drinking, illicit drug use, violence, drunk driving, not wearing helmets, and smoking. These behaviors contribute to injuries that may lead to premature death in males. In particular, the effect of risk-taking behavior on health is especially visible in the case of smoking. As smoking rates have fallen in the United States overall, less men engage in this behavior and the life expectancy gap between men and women has slightly decreased as a result.

The behaviors of men and women also vary in regards to diet and exercise, leading to differential health outcomes . On average, men exercise more than women, but their diet is less nutritious. Consequently, men are more likely to be overweight, while women are at greater risk for obesity. Exposure to violence is another social factor that has an influence on health. In general, women have a higher likelihood of experiencing sexual and intimate partner violence, while men are twice as likely to die from suicide or homicide.

Markedly, the impact of gender on health becomes especially salient in different socioeconomic contexts. In the United States, there is a large economic gender inequality with many economically disadvantaged women occupying much fewer positions of power than men. According to the Panel Study of Income Dynamics, "among adults with the strongest attachment to the labor force, only 9.6% of women earned more than $50,000 annually, compared with 44.5% of men." This gendered economic inequality is partly responsible for the gender-health paradox: the general trend that women live longer than men, but experience a greater degree of non-life-threatening chronic illnesses over the course of a lifetime. A low socioeconomic status in women contributes to feelings of a lack of personal control over the events in their lives, increased stress, and low self-esteem. Perpetual states of stress inflict damage on the bodies and minds of women, placing them at risk for physical ailments, such as heart disease and arthritis, as well mental health disorders, such as depression.

Another significant social factor is that men and women deal with their illnesses in different ways. Women generally have strong support networks and are able to rely on others for emotional support, with the potential to improve their states of health. In contrast, men are less likely to have strong support networks, they have fewer doctor visits, and often cope with their illnesses on their own. Also, men and women express pain in different ways. Researchers have observed that women openly express feelings of pain, while men are more reserved in this regard and prefer to appear tough even when they experience severe mental or physical suffering. This finding suggests that this is due to socialization processes. Women are taught to be submissive and emotional, while men are taught to be strong, powerful figures that do not show their emotions. The social stigma associated with expressions of pain prevents men from admitting their suffering to others, making it more difficult to overcome the pain.

Moreover, neighborhood effects have a greater influence on women than men. For instance, research findings suggest that women living in impoverished neighborhoods are more likely to experience obesity, while this effect is not as strong for men. The physical environment also generally impacts a woman's self-rated health. This effect can be explained by the fact that women spend more time at home than their male counterparts, as a result of higher unemployment rates, and therefore may be more exposed to negative environmental characteristics that take a toll on their health.

Finally, gender effects also vary with race, ethnicity, and nativity status. Notably, Christy Erving conducted a study in which she examined the gender differences in the health profiles of African Americans and Caribbean blacks (immigrants and U.S. born). One of the findings from this research is that on average, African American women report lower self-rated measures of health, worse physical health, and were more likely to experience severe chronic illnesses than men. This finding contradicts the gender-health paradox in the sense that researchers would expect morbidity rates to be higher for women, but less of the illnesses that they acquire should be debilitating. In contrast, the opposite trend is observed for U.S. born Caribbean blacks, with men more likely to experience chronic, life-threatening illnesses than women. The health outcomes of Caribbean black immigrants are somewhere in-between the health outcomes of U.S. born Caribbean blacks and African Americans, wherein the females have a lower value of self-reported health but experience equal rates of life-threatening, chronic disease as men. This data illustrates that even within one racial category, there can be stark gender differences in health on the basis of social differences within the groups that compose the race.

Race

Studies have shown that individuals that are racially and ethnically stigmatized, not just in the U.S., but globally as well, experience health issues such as mental and physical illness, and in some cases even death, in higher rates than the average individual. There has been some controversy around "race" being a determinant of disease and health issues, since there are unmeasured forms of background history that are potential factors in this research. Geographical origins and the types of environments individual races were exposed to are huge contributes to the health of a certain race, especially when the environment that they are in now is not the same as the one their race originates from geographically. 

Along with these factors, physical, psychological, social, and chemical environments are all included and accounted for. Including exposure over the course of one's life and through generations,and biological adaptation to these environmental exposures, including gene expression. An example of this is a study of hypertension between black people and whites. West Africans and people of West African descent levels of hypertension increased when they moved from Africa to the United States. Their levels of hypertension were twice as high as the levels of black people that were in Africa. While whites in the United States even had higher rates of hypertension than Black people in Africa, the black people in the United States rates of hypertension were higher than some predominately white populations in Europe. Again, this proves that when a race is taken out of their original geographic environment, they are more prone to disease and illness, because their genetic make-up was made for a specific type of environment. 

Transitioning from the environmental aspect of race and disease, there is a direct correlation between race and socioeconomic status which contributes to racial disparities in health. When it comes to death rates from heart disease, the rate is about twice as high for black men vs. white men. Now, death rates from heart disease are lower for both black and white women compared to their male counterparts, but the patterns of racial disparities and education disparities for women are similar to that of the men. Death from heart disease is about three times as higher for black women than white women. For both black men and women, racial differences in deaths from heart disease at every level of education is evident, with the racial gap being larger at the higher levels of education than at the lowest levels. There are a number of reasons why race matters in terms of health after socioeconomic status has been accounted for. For one, health is affected by adversity early on in one's life, such as traumatic stress, poverty, and abuse. These factors affect the physical and mental health of an individual. As we know, most of the people living in poverty in the United States are minorities, specifically African Americans, so unfortunately there is no surprise that they are the individuals with so many health issues.

Continuously, race is relevant to health issues, because of the non-equivalence of socioeconomic status indicators across racial groups. At the same level of education, minorities (black people and non-white Hispanic people) receive less income than their Anglo-white counterparts, as well as have less wealth and purchasing power. Namely, one of the biggest reasons that race matters in terms of health is due to racism. Both personal and institutionalized racism are very prominent in today's society, maybe not as blunt and easy to notice in comparison to the past, but it still exists. Certain residential segregation by race, such as redlining, has created very distinct racial differences in terms of education, employment, and opportunities. Opportunities such as access to good healthcare/medical care. Institutional and cultural racism can even harm minorities health through stereotypes and prejudices, which contributes to socioeconomic mobility and can reduce and limit resources and opportunities required for a healthy lifestyle.

Socioeconomic status is only one part of racial disparities in health that reflect larger social inequalities in society. Racism is a system that combines with, and sometimes changes, socioeconomic status to influence health, and race still matters for health when socioeconomic status is considered.

Socioeconomic status

Socioeconomic status is a multidimensional classification, often defined using an individual's income and level of education. Other related metrics can round out this definition; for example, in a 2006 study by authors Cox, McKevitt, Rudd and Wolfe, further categories included "occupation, home and goods ownership, and area-based deprivation indices" in their determination of status.

Income inequality has risen rapidly in the United States, pushing greater amounts of the population into positions of lower socioeconomic status. A study published in 1993 examined Americans who had passed away between May and August 1960, and paired the mortality information with income, education and occupation data for each person. The work found an inverse correlation between socioeconomic status and mortality rate, as well as an increasing strength of this pattern and its reflection of the growth of income inequality in the United States.

These findings, although concerned with total mortality of any cause, reflect a similar relationship between socioeconomic status and disease incidence or death in the United States. Disease composes a very significant portion of U.S. mortality; as of May 2017, 6 out of 7 of the leading causes of death in America are non-communicable diseases, including heart disease, cancer, lower respiratory diseases, and cerebrovascular diseases (stroke). Indeed, these diseases have been seen to disproportionately affect the socioeconomically disadvantaged, albeit to different degrees and with differing magnitude. Mortality rates associated with cardiovascular disease (CVD), including coronary heart disease (CHD) and stroke, were assessed for individuals across areas of differing income and income inequality. The authors found that the mortality rates for each of the three respective diseases were greater by a factor of 1.36, 1.26, and 1.60, in areas of higher inequality compared to lower inequality areas of similar income. Across areas of differing income and constant income inequality, the rate of death due to CVD, CHD and stroke was increased by a factor of 1.27, 1.15, and 1.33 in the lower income areas. These trends across two measures of variation in socioeconomic status reflect the complexity and depth of the relationship between disease and economic standing. The authors are careful to state that while these patterns exist, they are not sufficiently described as related by cause and effect. While correlating, health and status have arisen in the U.S. from interrelated forces that may intricately accumulate or negate one another due to specific historical contexts.

As this lack of cause and effect simplicity indicates, exactly where disease-related health inequality arises is murky, and multiple factors likely contribute. Important to an examination of disease and health in the context of a complicated classification like socioeconomic status is the degree to which these measures are tied up with mechanisms that are dependent upon the individual, and those that are regionally variant. In the aforementioned 2006 study, the authors define individualized factors within three categories, "material (eg, income, possessions, environment), behavioural (eg, diet, smoking, exercise) and psychosocial (eg, perceived inequality, stress)", and provide two categories for external, regionally varying factors, "environmental influences (such as provision of and access to services) and psychosocial influences (such as social support)." The interactive and compounding nature of these forces can shape and be shaped by socioeconomic status, presenting a challenge to researchers to tease apart the intersecting factors of health and status. In the 2006 study, authors examined the specific drivers of the correlation between stroke occurrence and socioeconomic status. Identifying more nuanced and interlocking factors, they cited risk behaviors, early life influences, and access to care as tied to socioeconomic status and thus health inequality.

Inequality in disease is intricately tangled up with stratification of social class and economic status in the United States. Correlations, often disease-dependent, between health and socioeconomic attainment have been demonstrated in numerous studies for numerous diseases. The causes of these correlations are interlocking and often related to factors varying between regions and individuals, and design of future studies concerning inequality in disease require careful thought to the multifaceted driving mechanisms of social inequality.

Environment

The neighborhoods and areas people live in, as well as their occupation, make up the environment in which they exist. People living in poverty stricken neighborhoods are at a greater risk for heart disease, possibly because the supermarkets in their area do not sell healthy foods and there is increased availability of stores selling alcohol and tobacco than in more affluent parts of town. People living in rural areas are also more susceptible to heart disease, as well. An agriculturally based diet rich in fat and cholesterol, combined with an isolated environment in which there is limited access to health care and ways to distribute information probably creates a pattern in which people living in rural environments have higher levels of heart disease. Occupational cancer is one way in which the environment one works in can increase their rate of disease. Employees exposed to smoke, asbestos, diesel fumes, paint, and chemicals in factories can develop cancer from their workplace. All of these jobs tend to be low-paying and typically held by low income individuals. The decreased amount of healthy food in stores located in low-income areas also contributes to the increased rates of diabetes for persons living in those neighborhoods. One of the best examples of this can be seen by observing the city of Jacksonville, Florida.

Food deserts in urban Jacksonville

In Jacksonville, Florida it is hard to find groceries stores around the area because it is surrounded by fats, sugar, and high in cholesterol markets. In Duval County, there are 177,000 food insecure individuals such as children, families,senior citizens, and veterans that do not know when they will have a chance to have another meal again. Nearly 60 percent of the food that is consumed in Duval County is processed. To combat this, agencies helped distribute food and they averaged 12.3 million meals over eight counties in Northern Florida. In Duval alone, 3.5 million meals were handed out to families. The image below shows all of the hunger-relief partner agencies located within Jacksonville's food deserts that get food from Feeding Northeast Florida. In all Feeding Northeast Florida provided 4.2 million pounds of food to agencies in food deserts. These numbers were stats recorded in 2016.

Water pollution

Just like Flint Jacksonville had a water crisis and found 23 different chemicals in their water supply. It was so bad that Jacksonville was labeled top 10 in worst water in the nation. They stood at number 10 because of the 23 different chemicals. The chemicals that were most found in the water in high volumes were trihalomethanes, which is made up of four different cleaning by products such as chloroform. Trihalomethanes are confirmed to be carcinogenic. Throughout the five year testing period, unsafe levels of trihalomethanes were found during the 32 months of testing, and levels that are considered illegal by the EPA were found in 12 of those months. In one of the testing periods the trihalomethanes were found at twice the EPA legal limit. Other chemicals such as lead and arsenic that can cause health problems to people, were also found in the drinking water.

Another way that water pollution is damaged is from nutrient overload. Nutrient overload is caused by manure and fertilizers, storm water runoff, and wastewater treatment plants. This occurs in a lot of Florida rivers and the rivers are contained with blue green algae that feed on all those nutrients. All the waste that is dumped into the rivers gets fed on by other plants and animals that release toxins in the area, which makes everything surrounded by it a deadly toxin as well. The toxins that are dumped into the rivers can cause discoloration in the rivers to make a dark blue and green color. By looking at the river most people can tell how dangerous and harmful it is to be around it. If the water were to somehow get into water companies people can receive serious harm from drinking and bathing with this water.

Education

Education level is a great predictor of socioeconomic status. On average, individuals with a bachelors, associates, and high school degrees will annually earn 64.5, 50, and 41 thousand dollars respectively. This means that the average bachelor's degree earner will receive approximately $1,000,000 more over their working life than an individual with only a high school degree. Furthermore, as authors Montez, Hummer, and Hayward explained, "In 2012, unemployment was 12.4 percent among adults who did not graduate high school, compared to 8.3 percent among adults with a high school diploma and 4.5 percent among college graduates." Because the relationship between socioeconomic status and the prevalence of disease has already been well established, education is indirectly responsible for an increased prevalence of disease among the impoverished. 

More directly, educational attainment is a great predictor of how likely an individual is to engage in risky, possibly disease causing, behaviors. In terms of smoking, which directly correlates to an increased risk for diseases like lung cancer, education is an important determining factor in the likelihood of an individual to smoke. As of 2009-10, 35 percent of adults who did not graduate high school were smokers, compared to 30 percent of high school graduates and just 13 percent of college graduates. High school graduates also smoked more packs, on average, each year than smokers who had graduated from college. Furthermore, individuals with a high school degree or less were 30% less likely to abstain from smoking for at least 3 months during their time as a regular smoker. Other studies have found that binge drinking is higher among those with college degrees, implying that binge drinking is a habitat developed by many during the college years.

Unhealthy dietary habits can also directly lead to diseases such as heart disease, hypertension, and type-2 diabetes. One of the leading causes of unhealthy eating habits is a lack of access to grocery stores, creating so called "food deserts." Studies have found that immediate access to a grocery store (within 1.5 mile radius) was 1.4 times less likely in areas where only 27%, or less, of the population was college graduates. The negative effects of these food deserts are exacerbated by the fact that impoverished neighborhoods also had an oversupply of liquor store, fast food restaurants, and convenience stores.

One significant risk for sexually active individuals is that of sexually transmitted diseases and infections. While studies have found that the correlation between education and carrying these is relatively low on average (and even less so for certain subsets such as Black women), there is a strong correlation between education and other risky sexual behaviors. Those with only a high school degree or less were significantly more likely to engage in risky practices such as early sexual initiation, sexual activity with those who use "shooting" street drugs such as heroin, and even prostitution. In addition, those with less education were also less likely to practice some safe sex practices such as condom use.

Studies have also found that adults with higher educational achievement were more likely to lead healthier lives. Intake of key nutrients such as Vitamins A and C, potassium, and calcium was positively correlated with education level. This is a critical statistic because those nutrients, such as Vitamin C, are critical in helping the body fight diseases and infections. There was also a correlation between education and exercise habits. A 2010 study found that while 85% of college graduates stated they exercised in the last month, only 68% of high school graduates and 61% of non-high school graduates said the same. Because exercise is so crucial to preventing diseases like hypertension and type 2 diabetes, this stark distinction between exercise habitats can have significant effects. By 2011, 15% of high school (or less) graduates had diabetes, compared to just 7% of college graduates.

Arguably the best way of seeing the true effects of education in the inequality of disease is to examine mortality levels, as Heart Disease, Cancer, and Lower Respiratory Diseases are the top three killers, respectively, of Americans every year. By age 25, if an individual does not have at least a high school degree, they will die an average of 9 years earlier than an otherwise similar college graduate. A different national study found that individuals with only bachelor's degrees were 26% more likely to die in the next 5 years than individuals of the same age with professional degrees such as a master's. Even more stark, Americans without a high school degree were almost twice as likely to die than those with a professional degree in the study's 5 year follow-up period.

Population health

From Wikipedia, the free encyclopedia

Income inequality and mortality in 282 metropolitan areas of the United States. Mortality is correlated with both income and inequality.

 

Population health has been defined as "the health outcomes of a group of individuals, including the distribution of such outcomes within the group". According to Akarowhe (2018), the working definition of population health is expressed thus; population health is an art, process, science and a product of enhancing the health condition of a specific number of people within a given geographical area - population health as an art, simply means that it is geared towards equal health care delivery to an anticipated group of people in a particular geographical location; as a science, it implies that it adopt scientific approach of preventive, therapeutic, and diagnostic service in proffering medical treatment to the health problem of people; as a product, it means that population health is directed toward overall health performance of people through health satisfaction within the said geographical area; and as a process it entails effective and efficient running of a health management/population health management system to cater for the health needs of the people. It is an approach to health that aims to improve the health of an entire human population. This concept does not refer to animal or plant populations. It has been described as consisting of three components. These are "health outcomes, patterns of health determinants, and policies and interventions". A priority considered important in achieving the aim of Population Health is to reduce health inequities or disparities among different population groups due to, among other factors, the social determinants of health, SDOH. The SDOH include all the factors (social, environmental, cultural and physical) that the different populations are born into, grow up and function with throughout their lifetimes which potentially have a measurable impact on the health of human populations. The Population Health concept represents a change in the focus from the individual-level, characteristic of most mainstream medicine. It also seeks to complement the classic efforts of public health agencies by addressing a broader range of factors shown to impact the health of different populations. The World Health Organization's Commission on Social Determinants of Health, reported in 2008, that the SDOH factors were responsible for the bulk of diseases and injuries and these were the major causes of health inequities in all countries. In the US, SDOH were estimated to account for 70% of avoidable mortality.

From a population health perspective, health has been defined not simply as a state free from disease but as "the capacity of people to adapt to, respond to, or control life's challenges and changes". The World Health Organization (WHO) defined health in its broader sense in 1946 as "a state of complete physical, mental, and social well-being and not merely the absence of disease or infirmity."

Healthy People 2020

Healthy People 2020 is a web site sponsored by the US Department of Health and Human Services, representing the cumulative effort of 34 years of interest by the Surgeon General's office and others. It identifies 42 topics considered social determinants of health and approximately 1200 specific goals considered to improve population health. It provides links to the current research available for selected topics and identifies and supports the need for community involvement considered essential to address these problems realistically.

The human role of economic inequality

Recently, human role has been encouraged by the influence of population growth there has been increasing interest from epidemiologists on the subject of economic inequality and its relation to the health of populations. There is a very robust correlation between socioeconomic status and health. This correlation suggests that it is not only the poor who tend to be sick when everyone else is healthy, heart disease, ulcers, type 2 diabetes, rheumatoid arthritis, certain types of cancer, and premature aging. Despite the reality of the SES Gradient, there is debate as to its cause. A number of researchers (A. Leigh, C. Jencks, A. Clarkwest—see also Russell Sage working papers) see a definite link between economic status and mortality due to the greater economic resources of the better-off, but they find little correlation due to social status differences. 

Other researchers such as Richard G. Wilkinson, J. Lynch, and G.A. Kaplan have found that socioeconomic status strongly affects health even when controlling for economic resources and access to health care. Most famous for linking social status with health are the Whitehall studies—a series of studies conducted on civil servants in London. The studies found that, despite the fact that all civil servants in England have the same access to health care, there was a strong correlation between social status and health. The studies found that this relationship stayed strong even when controlling for health-affecting habits such as exercise, smoking and drinking. Furthermore, it has been noted that no amount of medical attention will help decrease the likelihood of someone getting type 1 diabetes or rheumatoid arthritis—yet both are more common among populations with lower socioeconomic status. Lastly, it has been found that amongst the wealthiest quarter of countries on earth (a set stretching from Luxembourg to Slovakia) there is no relation between a country's wealth and general population health—suggesting that past a certain level, absolute levels of wealth have little impact on population health, but relative levels within a country do. The concept of psychosocial stress attempts to explain how psychosocial phenomenon such as status and social stratification can lead to the many diseases associated with the SES gradient. Higher levels of economic inequality tend to intensify social hierarchies and generally degrades the quality of social relations—leading to greater levels of stress and stress related diseases. Richard Wilkinson found this to be true not only for the poorest members of society, but also for the wealthiest. Economic inequality is bad for everyone's health. Inequality does not only affect the health of human populations. David H. Abbott at the Wisconsin National Primate Research Center found that among many primate species, less egalitarian social structures correlated with higher levels of stress hormones among socially subordinate individuals. Research by Robert Sapolsky of Stanford University provides similar findings.

Research

There is well-documented variation in health outcomes and health care utilization & costs by geographic variation in the U.S., down to the level of Hospital Referral Regions (defined as a regional health care market, which may cross state boundaries, of which there are 306 in the U.S.). There is ongoing debate as to the relative contributions of race, gender, poverty, education level and place to these variations. The Office of Epidemiology of the Maternal and Child Health Bureau recommends using an analytic approach (Fixed Effects or hybrid Fixed Effects) to research on health disparities to reduce the confounding effects of neighborhood (geographic) variables on the outcomes.

The importance of family planning programs

Family planning programs (including contraceptives, sexuality education, and promotion of safe sex) play a major role in population health. Family planning is one of the most highly cost-effective interventions in medicine. Family planning saves lives and money by reducing unintended pregnancy and the transmission of sexually transmitted infections.

For example, the United States Agency for International Development lists as benefits of its international family planning program:

• "Protecting the health of women by reducing high-risk pregnancies"
• "Protecting the health of children by allowing sufficient time between pregnancies"
• "Fighting HIV/AIDS through providing information, counseling, and access to male and female condoms"
• "Reducing abortions"
• "Supporting women's rights and opportunities for education, employment, and full participation in society"
• "Protecting the environment by stabilizing population growth"

Population health management (PHM)

One method to improve population health is population health management (PHM), which has been defined as "the technical field of endeavor which utilizes a variety of individual, organizational and cultural interventions to help improve the morbidity patterns (i.e., the illness and injury burden) and the health care use behavior of defined populations". PHM is distinguished from disease management by including more chronic conditions and diseases, by use of "a single point of contact and coordination", and by "predictive modeling across multiple clinical conditions". PHM is considered broader than disease management in that it also includes "intensive care management for individuals at the highest level of risk" and "personal health management... for those at lower levels of predicted health risk". Many PHM-related articles are published in Population Health Management, the official journal of DMAA: The Care Continuum Alliance.

The following road map has been suggested for helping healthcare organizations navigate the path toward implementing effective population health management:

• Establish precise patient registries
• Determine patient-provider attribution
• Define precise numerators in the patient registries
• Monitor and measure clinical and cost metrics
• Adhere to basic clinical practice guidelines
• Engage in risk-management outreach
• Acquire external data
• Communicate with patients
• Educate patients and engage with them
• Establish and adhere to complex clinical practice guidelines
• Coordinate effectively between care team and patient
• Track specific outcomes

Healthcare reform and population health

Healthcare reform is driving change to traditional hospital reimbursement models. Prior to the introduction of the Patient Protection and Affordable Care Act (PPACA), hospitals were reimbursed based on the volume of procedures through fee-for-service models. Under the PPACA, reimbursement models are shifting from volume to value. New reimbursement models are built around pay for performance, a value-based reimbursement approach, which places financial incentives around patient outcomes and has drastically changed the way US hospitals must conduct business to remain financially viable. In addition to focusing on improving patient experience of care and reducing costs, hospitals must also focus on improving the health of populations (IHI Triple Aim).

As participation in value-based reimbursement models such as accountable care organizations (ACOs) increases, these initiatives will help drive population health. Within the ACO model, hospitals have to meet specific quality benchmarks, focus on prevention, and carefully manage patients with chronic diseases. Providers get paid more for keeping their patients healthy and out of the hospital. Studies have shown that inpatient admission rates have dropped over the past ten years in communities that were early adopters of the ACO model and implemented population health measures to treat "less sick" patients in the outpatient setting. A study conducted in the Chicago area showed a decline in inpatient utilization rates across all age groups, which was an average of a 5% overall drop in inpatient admissions.

Hospitals are finding it financially advantageous to focus on population health management and keeping people in the community well. The goal of population health management is to improve patient outcomes and increase health capital. Other goals include preventing disease, closing care gaps, and cost savings for providers. In the last few years, more effort has been directed towards developing telehealth services, community-based clinics in areas with high proportion of residents using the emergency department as primary care, and patient care coordinator roles to coordinate healthcare services across the care continuum.

Health can be considered a capital good; health capital is part of human capital as defined by the Grossman model. Health can be considered both an investment good and consumption good. Factors such as obesity and smoking have negative effects on health capital, while education, wage rate, and age may also impact health capital. When people are healthier through preventative care, they have the potential to live a longer and healthier life, work more and participate in the economy, and produce more based on the work done. These factors all have the potential to increase earnings. Some states, like New York, have implemented statewide initiatives to address population health. In New York state there are 11 such programs. One example is the Mohawk Valley Population Health Improvement Program (http://www.mvphip.org/). These programs work to address the needs of the people in their region, as well as assist their local community based organizations and social services to gather data, address health disparities, and explore evidence-based interventions that will ultimately lead to better health for everyone. Following a similar approach, Cullati et al. developed a theoretical framework for the development and onset of vulnerability in later life based on the concept of "reserves". The advantages to use the concept of reserves in interdisciplinary studies, as compared with related concepts such as resources and capital, is to strengthen the importance of constitution and sustainability of reserves (the “use it or lose it” paradigm) and the presence of thresholds, below which functioning becomes challenging.

Statistics

In the United States, the National Center for Health Statistics is responsible for the collection of data on the health of citizens.

Polio eradication

From Wikipedia, the free encyclopedia

A child receives oral polio vaccine during a 2002 campaign to immunize children in India.

 

Poliovirus

 

A public health effort to permanently eliminate all cases of poliomyelitis (polio) infection around the world began in 1988, led by the World Health Organization (WHO), the United Nations Children's Fund (UNICEF) and the Rotary Foundation. These organizations, along with the U.S. Centers for Disease Control and Prevention (CDC) and The Gates Foundation, have spearheaded the campaign through the Global Polio Eradication Initiative (GPEI), which helps to coordinate vaccination campaigns, environmental monitoring, evaluation of possible polio cases and logistics. Successful eradication of infectious diseases has been achieved twice before, with smallpox and bovine rinderpest.

Prevention of disease spread is accomplished by vaccination. There are two kinds of polio vaccine—oral polio vaccine (OPV), which uses weakened poliovirus, and inactivated polio vaccine (IPV), which is injected. The OPV is less expensive and easier to administer, and can spread immunity beyond the person vaccinated, creating contact immunity. It has been the predominant vaccine used. However, under conditions of long-term vaccine virus circulation in under-vaccinated populations, mutations can reactivate the virus to produce a polio-inducing strain, while the OPV can also, in rare circumstances, induce polio or persistent asymptomatic infection in vaccinated individuals, particularly those that are immunodeficient. Being inactivated, the IPV is free of these risks but does not induce contact immunity. IPV is more costly and the logistics of delivery are more challenging.

The 33 diagnosed wild polio virus (WPV) cases worldwide in 2018 represented a 95% reduction from the 719 diagnosed cases in 2000 and a 99.99% reduction from the estimated 350,000 cases when the eradication effort began in 1988. Of the three strains of polio virus, the last recorded wild case caused by type 2 (WPV2) was in 1999, and WPV2 was declared eradicated in 2015. Type 3 (WPV3) is last known to have caused polio on 11 November 2012, with all wild-virus cases since that date being due to type 1 (WPV1). All three types are represented among the periodic cases arising from mutated oral vaccine strains, so-called circulating vaccine-derived poliovirus (cVDPV). India is the latest country to have officially stopped endemic transmission of polio, with its last reported case in 2011. Three countries remain where the disease is endemic—Afghanistan, Pakistan and Nigeria.

Factors influencing eradication of polio

Eradication of polio has been defined in various ways—as elimination of the occurrence of poliomyelitis even in the absence of human intervention, as extinction of poliovirus, such that the infectious agent no longer exists in nature or in the laboratory, as control of an infection to the point at which transmission of the disease ceased within a specified area, and as reduction of the worldwide incidence of poliomyelitis to zero as a result of deliberate efforts, and requiring no further control measures.

In theory, if the right tools were available, it would be possible to eradicate all infectious diseases that reside only in a human host. In reality there are distinct biological features of the organisms and technical factors of dealing with them that make their potential eradicability more or less likely. Three indicators, however, are considered of primary importance in determining the likelihood of successful eradication: that effective interventional tools are available to interrupt transmission of the agent, such as a vaccine; that diagnostic tools, with sufficient sensitivity and specificity, be available to detect infections that can lead to transmission of the disease; and that humans are required for the life-cycle of the agent, which has no other vertebrate reservoir and cannot amplify in the environment.

Strategy

The most important step in eradication of polio is interruption of endemic transmission of poliovirus. Stopping polio transmission has been pursued through a combination of routine immunization, supplementary immunization campaigns and surveillance of possible outbreaks. Several key strategies have been outlined for stopping polio transmission:

1. High infant immunization coverage with four doses of oral polio vaccine (OPV) in the first year of life in developing and endemic countries, and routine immunization with OPV and/or IPV elsewhere.
2. Organization of "national immunization days" to provide supplementary doses of oral polio vaccine to all children less than five years old.
3. Active surveillance for poliovirus through reporting and laboratory testing of all cases of acute flaccid paralysis. Acute flaccid paralysis (AFP) is a clinical manifestation of poliomyelitis characterized by weakness or paralysis and reduced muscle tone without other obvious cause (e.g., trauma) among children less than fifteen years old. AFP is also associated with a number of other pathogenic agents including enteroviruses, echoviruses, and adenoviruses, among others.
4. Expanded environmental surveillance to detect the presence of poliovirus in communities. Sewage samples are collected at regular and random sites and tested in laboratories for the presence of WPV or cVDPV. Since most polio infections are asymptomatic, transmission can occur in spite of the absence of polio-related AFP cases, and such monitoring helps to evaluate the degree to which virus continues to circulate in an area.
5. Targeted "mop-up" campaigns once poliovirus transmission is limited to a specific focal area.

Vaccination

There are two distinct polio vaccines. The oral polio vaccine (OPV, or Sabin vaccine) contains an attenuated poliovirus, 10,000 times less able to enter the circulation and cause polio, delivered as oral drops or infused into sugar cubes. It is highly effective and inexpensive (about US$0.12 per dose in 2016) and its availability has bolstered efforts to eradicate polio. A study carried out in an isolated Eskimo village showed that antibodies produced from subclinical wild virus infection persisted for at least 40 years. Because the immune response to oral polio vaccine is very similar to natural polio infection, it is expected that oral polio vaccination provides similar lifelong immunity to the virus. Due to its route of administration, it induces an immunization of the intestinal mucosa that protects against subsequent infection, though multiple doses are necessary to achieve effective prophylaxis. It can also produce contact immunity. Attenuated poliovirus derived from the oral polio vaccine is excreted, and infects and indirectly induces immunity in unvaccinated individuals, thus amplifying the effects of the doses delivered. The oral administration does not require special medical equipment or training. Taken together, these advantages have made it the preferred vaccine of many countries, and it has long been preferred by the global eradication initiative.

The primary disadvantage of the OPV derives from its inherent nature as an attenuated but active virus. It can induce vaccine-associated paralytic poliomyelitis (VAPP) in approximately 1 individual per every 2.4 million doses administered. Likewise, mutation during the course of persistent circulation in undervaccinated populations can lead to vaccine-derived poliovirus strains (cVDPV) that can induce polio at much higher rates. Until recently, a trivalent OPV containing all three virus strains was used, but with the eradication of wild poliovirus type 2 this was phased out in 2016 and replaced with bivalent vaccine containing just types 1 and 3, while use of monovalent type 2 OPV is restricted to regions with documented cVDPV2 circulation.

The inactivated polio vaccine (IPV, or Salk) contains trivalent fully inactivated virus, administered by injection. This vaccine cannot induce VAPP nor do cVDPV strains arise from it, but it likewise cannot induce contact immunity and thus must be administered to every individual. Added to this are greater logistical challenges. Though a single dose is sufficient for protection, administration requires medically trained vaccinators armed with single-use needles and syringes. Taken together, these factors result in substantially higher delivery costs. Original protocols involved intramuscular injection in the arm or leg, but recently subcutaneous injection using a lower dose (so-called fractional-dose IPV, fIPV) has been found to be effective, lowering costs and also allowing for more convenient and cost-effective delivery systems. The use of IPV results in serum immunity, but no intestinal immunity arises. As a consequence, a vaccinated individual is protected from contracting polio, but their intestinal mucosa can still be infected and serve as a reservoir for the excretion of live virus. For this reason, IPV is ineffective at halting ongoing outbreaks of WPV or cVDPV, but it has become the vaccine for choice for industrialized, polio-free countries.

While IPV does not itself induce mucosal immunity, it has been shown to boost the mucosal immunity from OPV, and WHO now favors a combined protocol. It is recommended that vulnerable children receive a dose of OPV at birth, then beginning at the age of 6 weeks a 'primary series' consisting of three OPV doses at least four weeks apart, along with one dose of IPV after 14 weeks. This combined IPV/OPV approach has also been used in outbreak suppression.

Herd immunity

Polio vaccination is also important in the development of herd immunity. For polio to occur in a population, there needs to be an infecting organism (poliovirus), a susceptible human population, and a cycle of transmission. Poliovirus is transmitted only through person-to-person contact and the transmission cycle of polio is from one infected person to another person susceptible to the disease, and so on. If the vast majority of the population is immune to a particular agent, the ability of that pathogen to infect another host is reduced; the cycle of transmission is interrupted, and the pathogen cannot reproduce and dies out. This concept, called community immunity or herd immunity, is important to disease eradication, because it means that it is not necessary to inoculate 100% of the population—a goal that is often logistically very difficult—to achieve the desired result. If the number of susceptible individuals can be reduced to a sufficiently small number through vaccination, then the pathogen will eventually die off.

When many hosts are vaccinated, especially simultaneously, the transmission of wild virus is blocked, and the virus is unable to find another susceptible individual to infect. Because poliovirus can only survive for a short time in the environment (a few weeks at room temperature, and a few months at 0–8 °C (32–46 °F)), without a human host the virus dies out.

Herd immunity is an important supplement to vaccination. Among those individuals who receive oral polio vaccine, only 95 percent will develop immunity. That means five of every 100 given the vaccine will not develop any immunity and will be susceptible to developing polio. According to the concepts of herd immunity this population whom the vaccine fails, are still protected by the immunity of those around them. Herd immunity can only be achieved when vaccination levels are high. It is estimated that 80–86 percent of individuals in a population must be immune to polio for the susceptible individuals to be protected by herd immunity. If routine immunization were stopped, the number of unvaccinated, susceptible individuals would soon exceed the capability of herd immunity to protect them.

Vaccine-derived poliovirus

Number of wild poliovirus cases, 1975–2017
(before 2000 may include small numbers of cVDPV cases)

 

Number of cVDPV cases, 2000-2018

 

While vaccination has played an instrumental role in the reduction of polio cases worldwide, the use of attenuated virus in the oral vaccine carries with it an inherent risk. The oral vaccine is a powerful tool in fighting polio in part because of its person-to-person transmission and resulting contact immunity. However, under conditions of long-term circulation in under-vaccinated populations, the virus can accumulate mutations that reverse the attenuation and result in vaccine virus strains that themselves cause polio. As a result of such circulating vaccine-derived poliovirus (cVDPV) strains, polio outbreaks have periodically recurred in regions that have long been free of the wild virus, but where vaccination rates have fallen. Oral vaccines can also give rise to persistent infection in immunodeficient individuals, with the virus eventually mutating into a more virulent immunodeficiency-associated vaccine-derived poliovirus (iVDPV). In particular the type 2 strain seems prone to reversions, so in 2016 the eradication effort abandoned the trivalent oral vaccine containing attenuated strains of all three virus types, and replaced it with a bivalent oral vaccine lacking the type 2 virus. Eradication efforts will eventually require all oral vaccination to be discontinued in favor of the use of injectable vaccines. These vaccines are more expensive and harder to deliver, and they lack the ability to induce contact immunity because they contain only killed virus, but they likewise are incapable of giving rise to vaccine-derived viral strains.

Surveillance

A global program of surveillance for the presence of polio and the poliovirus plays a critical role in assessment of eradication and in outbreak detection and response. Two distinct methods are used in tandem: Acute Flaccid Paralysis (AFP) surveillance and environmental surveillance.

Monitoring for AFP aims at identifying outbreaks of polio by screening patients displaying symptoms consistent with but not exclusive to severe poliovirus infection. Stool samples are collected from children presenting with AFP and evaluated for the presence of poliovirus by accredited laboratories in the Global Polio Laboratory Network. Since rates of non-polio AFP are expected to be constant and large compared to polio cases, the frequency of non-polio AFP reported in a population is indicative of the effectiveness of surveillance, as is the proportion of AFP patients from whom high-quality stool samples are collected and tested, with a target of at least 80%.

Environmental surveillance is used to supplement AFP surveillance. This entails the routine testing of sewage samples for the presence of virus. This not only allows the effectiveness of vaccination efforts to be evaluated in countries with active transmission, but also allows the detection of new outbreaks in countries without known transmission. The GPEI currently conducts environmental surveillance in 44 countries, 24 of which are in Africa.

Obstacles

Among the greatest obstacles to global polio eradication are the lack of basic health infrastructure, which limits vaccine distribution and delivery, the crippling effects of civil war and internal strife, and the sometimes oppositional stance that marginalized communities take against what is perceived as a potentially hostile intervention by outsiders. Another challenge has been maintaining the potency of live (attenuated) vaccines in extremely hot or remote areas. The oral polio vaccine must be kept at 2 to 8 °C (36 to 46 °F) for vaccination to be successful.

An independent evaluation of obstacles to polio eradication requested by the WHO and conducted in 2009 considered the major obstacles in detail by country. In Afghanistan and Pakistan, they concluded that the most significant barrier was insecurity; but that managing human resources, political pressures, the movement of large populations between and within both countries, inadequately resourced health facilities, also posed problems, as well as technical issues with the vaccine. In India, the major challenge appeared to be the high efficiency of transmission within the populations of Bihar and Uttar Pradesh states, set against the low (~80% after three doses against type 1) seroconversion response seen from the vaccine. In Nigeria, meanwhile, the most critical barriers identified were management issues, in particular the highly variable importance ascribed to polio by different authorities at the local government level, although funding issues, community perceptions of vaccine safety, inadequate mobilisation of community groups, and issues with the cold chain also played a role. Finally, in those countries where international spread from endemic countries had resulted in transmission becoming re-established—namely Angola, Chad, and South Sudan, the key issues identified were underdeveloped health systems and low routine vaccine coverage, although low resources committed to Angola and South Sudan for the purpose of curtailing the spread of polio and climatic factors were also identified as playing a role.

Two additional challenges are found in unobserved polio transmission and in vaccine-derived poliovirus. First, most polio infections are asymptomatic or result in minor symptoms, with less than 1% of infections leading to paralysis and most infected people are unaware that they carry the disease, allowing polio to spread widely before cases are seen. In 2000 using new screening techniques for the molecular characterization of outbreak viral strains, it was discovered that some of the outbreaks taking place were actually caused by circulating vaccine-derived poliovirus, following mutations or recombinations in the attenuated strain used for the oral polio vaccine. This altered the strategy envisioned for the discontinuation of vaccination following polio eradication, necessitating an eventual switch to the more expensive and logistically more problematic inactivated polio vaccine, since continued use of the oral inactivated virus would continue to produce such revertant infection-causing strains. The risk of vaccine-derived polio will persist long after the switch to inactivated vaccine, since a small number of chronic excretors continue to produce active virus for years (or even decades) after their initial exposure to the oral vaccine.

In a 2012 interview with Pakistani newspaper Dawn, Dr. Hussain A. Gezari, WHO's special envoy on global polio eradication and primary healthcare, gave his views on obstacles to eradication. He said the biggest hurdle in making Pakistan polio-free was holding district health officials properly accountable—in national eradication campaigns officials had hired their own relatives, even young children. "How do you expect a seven-year-old thumb-sucking kid to implement a polio campaign of the government," said Dr Gezari. He added that, in spite of this, "the first national campaign was initiated by your government in 1994 and that year Pakistan reported 25,000 polio cases, and the number was just 198 last year, which clearly shows that the programme is working."

Opposition to vaccination efforts

One factor contributing to the continued circulation of polio immunization programs has been opposition in some countries.

In the context of the United States invasion of Afghanistan and the subsequent 2003 invasion of Iraq, rumours arose in the Muslim world that immunization campaigns were using intentionally-contaminated vaccines to sterilize local Muslim populations or to infect them with HIV. In Nigeria these rumours fit in with a longstanding suspicion of modern biomedicine, which since its introduction during the era of colonialism has been viewed as a projection of the power of western nations. Refusal of vaccination came to be viewed as resistance to western expansionism, and when the contamination rumours led the Nigerian Supreme Council for Sharia to call for a region-wide boycott of polio vaccination, polio cases in the country increased more than five-fold between 2002 and 2006, with the uncontrolled virus then spreading across Africa and globally. In Afghanistan and Pakistan, fears that the vaccine contained contraceptives were one reason given by the Taliban in issuing fatwas against polio vaccination. Skepticism in the Muslim world was exacerbated when it was learned in 2011 that the Central Intelligence Agency (CIA) had conducted a fake hepatitis B immunization campaign to collect blood samples from Osama bin Laden's Abbottabad compound in order to confirm the genetic identity of the children living there, and by implication his own presence, leading directly to his killing. In a letter written to CIA director Leon Panetta, the InterAction Alliance, a union of about 200 U.S.-based non-government organizations, deplored the actions of the CIA in using a vaccination campaign as a cover. Pakistan reported the world's highest number of polio cases (198) in 2011. Religious boycotts based on contamination concerns have not been limited to the Muslim world. In 2015, after claiming that a tetanus vaccine contained a contraceptive, a group of Kenyan Catholic bishops called on their followers to boycott a planned round of polio vaccination. This did not have a major effect on vaccination rates, and dialog along with vaccine testing forestalled further boycott calls.

Other religion-inspired refusals arise from concerns over whether the virus contains pig-derived products, and hence are haram (forbidden) in Islam, prohibitions against taking of animal life that may be required for vaccine production, or a resistance to interfering with divinely-directed disease processes. Concerns were addressed through extensive outreach, directed both toward the communities involved and respected clerical bodies, as well as promoting local ownership of the eradication campaign in each region. In early 2012, some parents refused to get their children vaccinated in Khyber Pakhtunkhwa and in the Federally Administered Tribal Areas (FATA) but religious refusals in the rest of the country had "decreased manifold". Even with the express support of political leaders, polio workers or their accompanying security guards have been kidnapped, beaten, or assassinated.

Polio vaccination efforts have also faced resistance in another form. The priority placed on vaccination by national authorities has turned it into a bargaining chip, with communities and interest groups resisting vaccination, not due to direct opposition, but to leverage other concessions from governmental authorities. In Nigeria this has taken the form of 'block rejection' of vaccination that is only resolved when state officials agree to repair or improve schools and health-care facilities, pave roads or install electricity. There have been several instances of threatened boycotts by health workers in Pakistan over payment disputes. Some governments have been accused of withholding vaccination or the necessary accompanying infrastructure from regions where opposition to their rule is high.

Polio eradication criteria

A country is regarded as polio free or non-endemic if no cases have been detected for a year. However, it is still possible polio circulates under these circumstances, as was the case for Nigeria, where a particular strain of virus resurfaced after five years in 2016. This can be due to chance, limited surveillance and under-vaccinated populations. Moreover, for the currently circulating virus WPV1, only 1 in 200 infection cases exhibit symptoms of polio paralysis in non-vaccinated children, and possibly even fewer in vaccinated children. Therefore, even a single case is considered an epidemic. According to modeling, it can take four to six months of no reported cases to achieve only a 50% chance of eradication, and one to two years for e.g. 95% chance. Sensitivity of monitoring for circulation can be improved by sampling sewage. In Pakistan in the last couple of years, the number of paralysis cases has dropped relatively faster than the positive environmental samples, which has shown no progress since 2015. The presence of multiple infections with the same strain in the upstream area may not be detectable, so there are some saturation effects when monitoring the number of positive environmental samples. Furthermore, virus may shed beyond the expected duration of several weeks in certain individuals. Contagiousness can not be readily excluded. For a polio virus to be certified as eradicated worldwide, at least three years of good surveillance without cases needs to be achieved, though this period may need to be longer for a strain like WPV3, where a lower proportion of those infected demonstrate symptoms, or if sewer samples stay positive. Wild poliovirus type 2 was certified eradicated in 2015, the last case having been detected in 1999. Wild poliovirus type 3 has not been detected since 2012, but its eradication has yet to be certified, and the Global Commission for the Certification of Poliomyelitis Eradication in 2017 recommended not certifying its eradication independent of that of WPV1, and hence of wild poliovirus as a whole. This recommendation would mean that type WPV3 will not be removed from the bivalent oral vaccine, as was considered necessary with WPV2 due to its high risk of giving rise to cVDPV strains, but rather oral vaccination for WPV3 will continue until total eradication of polio allows all oral vaccination to cease.

Timeline

International wild poliovirus cases by year
Year	Estimated	Recorded
1975	—	49,293
...
1980	400,000	52,552
...
1985	—	38,637
...
1988	350,000	35,251
...
1990	—	23,484
...
1993	100,000	10,487
...
1995	—	7,035
...
2000	—	719
...
2005	—	1,979
...
2010	—	1,352
2011	—	650
2012	—	223
2013	—	416
2014	—	359
2015	—	74
2016	—	37
2017	—	22
2018	—	33

Pre-1988

Kindergarten children receive an very early oral polio vaccine in 1960 in East Germany.

 

Following the widespread use of poliovirus vaccine in the mid-1950s, the incidence of poliomyelitis declined rapidly in many industrialized countries. Czechoslovakia became the first country in the world to scientifically demonstrate nationwide eradication of poliomyelitis in 1960. In 1962—just one year after Sabin's oral polio vaccine (OPV) was licensed in most industrialized countries—Cuba began using the oral vaccine in a series of nationwide polio campaigns. The early success of these mass vaccination campaigns suggested that polioviruses could be globally eradicated. The Pan American Health Organization (PAHO), under the leadership of Ciro de Quadros, launched an initiative to eradicate polio from the Americas in 1985.

Much of the work towards eradication was documented by Brazilian photographer Sebastião Salgado, as a UNICEF Goodwill Ambassador, in the book The End of Polio: Global Effort to End a Disease.

1988–2000

In 1988, the World Health Organization, together with Rotary International, UNICEF, and the U.S. Centers for Disease Control and Prevention passed the Global Polio Eradication Initiative, with the goal of eradicating polio by the year 2000. The initiative was inspired by Rotary International's 1985 pledge to raise $120 million toward immunising all of the world's children against the disease. The last case of wild poliovirus poliomyelitis in the Americas was reported in Peru, August 1991.

On 20 August 1994 the Americas were certified as polio-free. This achievement was a milestone in efforts to eradicate the disease. 

In 1994 the Indian Government launched the Pulse Polio Campaign to eliminate polio. The current campaign involves annual vaccination of all children under age five.

In 1995 Operation MECACAR (Mediterranean, Caucasus, Central Asian Republics and Russia) were launched; National Immunization Days were coordinated in 19 European and Mediterranean countries. In 1998, Melik Minas of Turkey became the last case of polio reported in Europe. In 1997 Mum Chanty of Cambodia became the last person to contract polio in the Indo-West Pacific region. In 2000 the Western Pacific Region (including China) was certified polio-free.

In October 1999, the last isolation of type 2 poliovirus occurred in India. This type of poliovirus was declared eradicated.

Also in October 1999, The CORE Group—with funding from the United States Agency for International Development (USAID)—launched its effort to support national eradication efforts at the grassroots level. The CORE Group initiated this initiative in Bangladesh, India and Nepal in South Asia, and in Angola, Ethiopia and Uganda in Africa.

2001–2005

Disability-adjusted life year for poliomyelitis per 100,000 inhabitants in 2004

no data   <0 .3="" span="">   0.3–0.75   0.75–1.2   1.2–1.65   1.65–2.1   2.1–2.55

2.55–3   3–4   4–5   5–7.5   7.5–10   >10

By 2001, 575 million children (almost one-tenth the world's population) had received some 2 billion doses of oral polio vaccine. The World Health Organization announced that Europe was polio-free on 21 June 2002, in the Copenhagen Glyptotek.

In 2002, an outbreak of polio occurred in India. The number of planned polio vaccination campaigns had recently been reduced, and populations in northern India, particularly from the Islamic background, engaged in mass resistance to immunization. At this time, the Indian state Uttar Pradesh accounted for nearly two-thirds of total worldwide cases reported. However, by 2004, India had adopted strategies to increase ownership of polio vaccinations in marginalized populations, and the immunity gap in vulnerable groups rapidly closed.

In August 2003, rumors spread in some states in Nigeria, especially Kano, that the vaccine caused sterility in girls. This resulted in the suspension of immunization efforts in the state, causing a dramatic rise in polio rates in the already endemic country. On 30 June 2004, the WHO announced that after a 10-month ban on polio vaccinations, Kano had pledged to restart the campaign in early July. During the ban the virus spread across Nigeria and into 12 neighboring countries that had previously been polio-free. By 2006, this ban would be blamed for 1,500 children being paralyzed and had cost $450 million for emergency activities. In addition to the rumors of sterility and the ban by Nigeria's Kano state, civil war and internal strife in the Sudan and Côte d'Ivoire have complicated WHO's polio eradication goal. In 2004, almost two-thirds of all the polio cases in the world occurred in Nigeria (760 out of 1,170 total).

Countries with polio cases in 2005

In May 2004 the first case of the polio outbreak in Sudan was detected. The reemergence of polio led to stepped up vaccination campaigns. In the city of Darfur, 78,654 children were immunized and 20,432 more in southern Sudan (Yirol and Chelkou).

In 2005 there were 1,979 cases of wild poliovirus (excludes vaccine-derived polio viruses). Most cases were located in two areas: the Indian subcontinent and Nigeria. Eradication efforts in the Indian sub-continent met with a large measure of success. Using the Pulse Polio campaign to increase polio immunization rates, India recorded just 66 cases in 2005, down from 135 cases reported in 2004, 225 in 2003, and 1,600 in 2002.

Yemen, Indonesia and Sudan, countries that had been declared polio-free since before 2000, each reported hundreds of cases—probably imported from Nigeria. On 5 May 2005, news reports broke that a new case of polio was diagnosed in Java, Indonesia, and the virus strain was suspected to be the same as the one that has caused outbreaks in Nigeria. New public fears over vaccine safety, which were unfounded, impeded vaccination efforts in Indonesia. In summer 2005 the WHO, UNICEF and the Indonesian government made new efforts to lay the fears to rest, recruiting celebrities and religious leaders in a publicity campaign to promote vaccination.

In the United States on 29 September 2005, the Minnesota Department of Health identified the first occurrence of vaccine derived polio virus (VDPV) transmission in the United States since OPV was discontinued in 2000. The poliovirus type 1 infection occurred in an unvaccinated, immunocompromised infant girl aged 7 months (the index patient) in an Amish community whose members predominantly were not vaccinated for polio.

2006–2010

In 2006 only four countries in the world (Nigeria, India, Pakistan and Afghanistan) were reported to have endemic polio. Cases in other countries are attributed to importation. A total of 1,997 cases worldwide were reported in 2006; of these the majority (1,869 cases) occurred in countries with endemic polio. Nigeria accounted for the majority of cases (1,122 cases) but India reported more than ten times more cases this year than in 2005 (676 cases, or 30% of worldwide cases). Pakistan and Afghanistan reported 40 and 31 cases respectively in 2006. Polio re-surfaced in Bangladesh after nearly six years of absence with 18 new cases reported. "Our country is not safe, as neighbours India and Pakistan are not polio free", declared Health Minister ASM Matiur Rahman.

In 2007 there were 1,315 cases of poliomyelitis reported worldwide. Over 60% of cases (874) occurred in India; while in Nigeria, the number of polio cases fell dramatically, from 1,122 cases reported in 2006 to 285 cases in 2007. Officials credit the drop in new infections to improved political control in the southern states and resumed immunisation in the north, where Muslim clerics led a boycott of vaccination in late 2003. Local governments and clerics allowed vaccinations to resume on the condition that the vaccines be manufactured in Indonesia, a majority Muslim country, and not in the United States. Turai Yar'Adua, wife of recently elected Nigerian president Umaru Yar'Adua, made the eradication of polio one of her priorities. Attending the launch of immunization campaigns in Birnin Kebbi in July 2007, Turai Yar'Adua urged parents to vaccinate their children and stressed the safety of oral polio vaccine.

In July 2007, a student traveling from Pakistan imported the first polio case to Australia in over 20 years. Other countries with significant numbers of wild polio virus cases include the Democratic Republic of the Congo, which reported 41 cases, Chad with 22 cases, and Niger and Myanmar, each of which reported 11 cases.

In 2008, 19 countries reported cases and the total number of cases was 1,652. Of these, 1,506 occurred in the four endemic countries and 146 elsewhere. The largest number were in Nigeria (799 cases) and India (559 cases): these two countries contributed 82.2 percent of all cases. Outside endemic countries Chad reported the greatest number (37 cases).

In 2009, a total of 1,606 cases were reported in 23 countries. Four endemic countries accounted for 1,256 of these, with the remaining 350 in 19 sub-Saharan countries with imported cases or re-established transmission. Once again, the largest number were in India (741) and Nigeria (388). All other countries had less than one hundred cases: Pakistan had 89 cases, Afghanistan 38, Chad 65, Sudan 45, Guinea 42, Angola 29, Côte d'Ivoire 26, Benin 20, Kenya 19, Niger 15, Central African Republic 14, Mauritania 13 and Sierra Leone and Liberia both had 11. The following countries had single digit numbers of cases: Burundi 2, Cameroon 3, the Democratic Republic of the Congo 3, Mali 2, Togo 6 and Uganda 8. 

According to figures updated in April 2012, the WHO reported that there were 1,352 cases of wild polio in 20 countries in 2010. Reported cases of polio were down 95% in Nigeria (to a historic low of 21 cases) and 94% in India (to a historic low of 42 cases) compared to the previous year, with little change in Afghanistan (from 38 to 25 cases) and an increase in cases in Pakistan (from 89 to 144 cases). An acute outbreak in Tajikistan gave rise to 460 cases (34% of the global total), and was associated with a further 18 cases across Central Asia (Kazakhstan and Turkmenistan) and the Russian Federation, with the most recent case from this region being reported from Russia 25 September. These were the first cases in the WHO European region since 2002. The Republic of Congo (Brazzaville) saw an outbreak with 441 cases (30% of the global total). At least 179 deaths were associated with this outbreak, which is believed to have been an importation from the ongoing type 1 outbreak in Angola (33 cases in 2010) and the Democratic Republic of the Congo (100 cases).

2011–2015

In 2011, 650 WPV cases were reported in sixteen countries: the four endemic countries—Pakistan, Afghanistan, Nigeria and India—as well as twelve others. Polio transmission recurred in Angola, Chad and the Democratic Republic of the Congo. Kenya reported its first case since 2009, while China reported 21 cases, mostly among the Uyghurs of Hotan prefecture, Xinjiang, the first cases since 1994.

The total number of wild-virus cases reported in 2012 was 223, lower than any previous year. These were limited to five countries—Nigeria, Pakistan, Afghanistan, Chad, and Niger—of which all except Nigeria had fewer cases than in 2011. Several additional countries, Chad, Democratic Republic of the Congo, Somalia and Yemen, saw outbreaks of circulating vaccine-derived polio. The last reported type 3 case of polio worldwide had its onset 11 November 2012 in Nigeria; the last wild case outside Nigeria was in April 2012 in Pakistan, and its absence from sewage monitoring in Pakistan suggests that active transmission of this strain has ceased there. A total of 416 wild-virus cases were reported in 2013, almost double the previous year. Of these, cases in endemic countries dropped from 197 to 160, while those in non-endemic countries jumped from 5 to 256 owing to two outbreaks: one in the Horn of Africa, and one in Syria.

In April, a case of wild polio in Mogadishu was reported, the first in Somalia since 2007. By October, over 170 cases had been reported in the country, with more cases in neighboring Kenya and the Somali Region of Ethiopia. 

Routine sewage monitoring in 2012 had detected a WPV1 strain of Pakistani origin in Cairo, sparking a major vaccination push there. The strain spread to Israel, where there was widespread environmental detection, but like Egypt, no paralysis cases. It had more severe consequences when it spread to neighboring Syria, with the total number of cases eventually reaching 35, the first outbreak there since 1999.

In late April 2013, the WHO announced a new $5.5 billion, 6-year cooperative plan (called the 2013–18 Polio Eradication and Endgame Strategic Plan) to eradicate polio from its last reservoirs. The plan called for mass immunization campaigns in the three remaining endemic countries, and also dictated a switch to inactivated virus injections, to avoid the risk of the vaccine-derived outbreaks that occasionally occur from use of the live-virus oral vaccine.

In 2014, there were 359 reported cases of wild poliomyelitis, spread over twelve countries. Pakistan had the most with 306, an increase from 93 in 2013, which was blamed on Al Qaeda and Taliban militants preventing aid workers from vaccinating children in rural regions of the country. On 27 March 2014, the WHO announced the eradication of poliomyelitis in the South-East Asia Region, in which the WHO includes eleven countries: Bangladesh, Bhutan, North Korea, India, Indonesia, Maldives, Myanmar, Nepal, Sri Lanka, Thailand and Timor-Leste. With the addition of this region, the proportion of world population living in polio-free regions reached 80%. The last case of wild polio in the South-East Asia Region was reported in India on 13 January 2011.

During 2015, 74 cases of wild poliomyelitis were reported worldwide, 54 in Pakistan and 20 in Afghanistan. There were 32 circulating vaccine-derived poliovirus (cVDPV) cases in 2015.

On 25 September 2015, the WHO declared that Nigeria was no longer considered endemic for wild polio virus, with no reported case of wild polio virus having been reported since 24 July 2014. A WPV1 strain not seen in 5 years resurfaced in Nigeria the following year.

WPV2 was declared eradicated in September 2015 as it has not been seen since 1999 and WPV3 may be eradicated as it has not been seen since 2012. cVDPV type 2 was still causing paralysis in some countries due to a years-long evolution in under-immunized populations.

Reported polio cases in 2011

 

Reported polio cases in 2012

 

Reported polio cases in 2013 

 

Reported polio cases in 2014 

 

Reported polio cases in 2015

2016

There were 37 reported WPV1 cases with an onset of paralysis in 2016, half as many as in 2015. Twenty of these cases occurred in Pakistan, thirteen in Afghanistan, and four in Nigeria. The cases of WPV1 in Nigeria were viewed as a setback, there having been no detected cases caused by the wild virus there in almost two years, yet genetic analysis showed that the virus was of a strain circulating undetected since 2011 in regions inaccessible due to the activities of Boko Haram.

The 2015 cVDPV1 outbreak in Laos continued into 2016, with three cases in January. Two separate strains of cVDPV2 were reported in Nigeria's Borno and Sekoto states, the latter resulting in one case. In Pakistan a new strain of cVDPV2 arose in the Quetta area, with one instance of paralysis.

Environmental samples from Hyderabad, India from January 2015 to May 2016 showed the ongoing presence of a cVDPV2 strain in that city, without diagnosed cases. Due to shortages in the global supply of injectable vaccine, an emergency campaign was launched using vaccine at one fifth the normal dose (fractional-Dose Inactivated Polio Vaccine, or fIPV), the first mass vaccination using this dosage of injectable vaccine.

Attacks on polio vaccination campaigns continued. A suicide bombing in Quetta in January and a pair of attacks by gunmen in Karachi in April targeted Pakistani security personnel protecting vaccinators, while in January three Afghan vaccination workers disappeared and their bodies were found weeks later.

Because cVDPV2 strains continued to arise from trivalent oral vaccine that included attenuated WPV2, in April and May 2016 this vaccine was replaced with a bivalent version lacking WPV2 as well as trivalent injected inactivated vaccine that cannot lead to cVDPV cases. This is expected to prevent new strains of cVDPV2 from arising and allow eventual cessation of WPV2 vaccination.

2017

There were 22 reported WPV1 polio cases with onset of paralysis in 2017, down from 37 in 2016. Eight of the cases were in Pakistan and 14 in Afghanistan, where genetic typing showed repeated introduction from Pakistan as well as local transmission. In Pakistan, transmission of several genetic lineages of WPV1 seen in 2015 had been interrupted by September 2017, though at least two genetic clusters remain. In spite of a significant drop in detected cases in Pakistan, there was an increase in the percentage of environmental samples that test positive for the polio virus, suggesting gaps in identification of infected individuals. In the third country where polio remains endemic, Nigeria, there were no cases, though as few as 7% of infants were fully vaccinated in some districts. An April 2017 spill at a vaccine production facility in the Netherlands resulted in one asymptomatic infection.

Laos was declared free of cVDPV1 in March, but three distinct cVDPV2 outbreaks occurred in the Democratic Republic of the Congo, one of them or recent origin, the other two having circulated undetected for more than a year. Together they caused 20 cases by year's end. In Syria a large outbreak began at Mayadin, Deir ez-Zor Governorate, a center of fighting in the Syrian Civil War and also spreading to neighboring districts saw 74 confirmed cases from a viral strain that had circulated undetected for about two years. Circulation of multiple genetic lines of cVDPV2 was also detected in Banadir province, Somalia, but no infected individuals were identified. WHO's Strategic Advisory Group of Experts on Immunization recommended that cVDPV2 suppression be prioritized over targeting WPV1, and according to protocol OPV2 is restricted to this purpose. 

The 2016 global switch in vaccination methods resulted in shortages of the injectable vaccine, and led the WHO in April 2017 to recommend general use of the fIPV vaccination protocol, involving subcutaneous injection of a lower dose than used in the standard intramuscular delivery.

2018

There were 33 reported WPV1 paralysis cases with an onset of paralysis in 2018 – 21 in Afghanistan and 12 in Pakistan. In Pakistan, three of the cases occurred in Kohlu District in Balochistan, with eight in Khyber Pakhtunkhwa, and one in the greater Karachi area, Sindh. Viral circulation across much of the country, including several major urban areas, led to wild poliovirus detection in 20% of the year's environmental samples. The rates of parental refusal for vaccination are increasing. Cases in Afghanistan represented two transmission clusters, one in Kandahar, Urozgan and Helmand Provinces in the south, the other in the adjacent Nuristan, Kunar and Nangarhar Provinces in the northeast, on the Pakistani border. Roughly half of recent Afghanistan isolates were genetically closer to isolates from Pakistan than to other Afghani samples, suggesting significant trans-border transmission. Recent cases in Afghanistan and Pakistan are due to three genetic clusters: R4B5C5B2 in the northern corridor in both countries, and the remaining cases are R4B5C4D in Pakistan, including five near the northern corridor, and R4B5C4C in Afghanistan. Though in 2017, nine of the detected viruses derived from long chains of undetected transmission, such long-chain transmission may have subsided in both Pakistan and Afghanistan in 2018, with the total number of circulating viral strains also dropping in both countries. Nigeria, the third country classified as having endemic transmission, passed two full years without a detected wild-virus case, but security concerns continued to limit access to some areas of the country and elimination of WPV transmission could not be confirmed. 

Cases caused by vaccine-derived poliovirus were reported in seven countries, with more than 100 total cases. Surveillance detected nine strains of cVDPV in 2018 in seven countries. In the Democratic Republic of Congo, one of the outbreaks of cVDPV2 first detected in 2017 caused no additional cases, but suppression of the other two with OPV2 proved insufficient: not only did they continue, but the vaccination efforts gave rise to a novel cVDPV2 outbreak. The country experienced a total of 20 cases in 2018. Two separate cVDPV2 outbreaks in northern Nigeria produced 34 cases, as well as giving rise to 10 cases in the neighboring Niger. In Somalia, cVDPV2 continued to circulate, causing several polio cases and detected in environmental samples from as far as Nairobi, Kenya. This virus, along with newly-detected cVDPV3, caused twelve total cases in the country, including one patient infected by both strains. The large number of children residing in areas inaccessible to health workers represent a particular risk for undetected cVDPV outbreaks. A cVDPV2 outbreak in Mozambique also resulted in a single case. Response to the Syrian cVDPV2 outbreak continued into 2018, and virus transmission was successfully interrupted. In Papua New Guinea, a cVDPV1 strain arose, causing twenty-six polio cases across 9 provinces, while a single diagnosed cVDPV1 case in neighboring Western New Guinea, Indonesia, resulted from a distinct outbreak.

2019

As of 12 June, twenty nine WPV1 paralysis cases had been detected in 2019, eight in Afghanistan and twenty one in Pakistan, with the latter already exceeding total the number of cases in the country in 2018. Trans-border migration continues to play a role in polio transmission in the two countries. While problematic, this has fostered a dangerous false-narrative in both nations, blaming the other for the presence and spread of polio in their own country. Environmental sampling in Pakistan has recently shown the virus' presence in eight urban areas, a setback officials attribute primarily to vaccine refusal. Opponents to vaccination in Pakistan launched a series of attacks in April that left a vaccinator and two security men dead, while false rumors and hoax videos reporting vaccine toxicity have also disrupted vaccination efforts there. Wild poliovirus of Pakistani origin has also been detected in environmental samples in Iran.

The cVDPV2 outbreaks in Nigeria, the Democratic Republic of Congo, and Somalia continued into 2019. The Nigeria outbreaks have caused eight reported paralysis cases, plus one in neighboring Niger, while cVDPV2 virus has also been detected in environmental samples from Cameroon. Somalia has seen two cases, while the DRC has had one case. A new outbreak has caused one case in Angola, in a region bordering where OPV2 vaccine had been used to fight the DRC outbreak.