Economic epidemiology

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Economic epidemiology is a field at the intersection of epidemiology and economics. Its premise is to incorporate incentives for healthy behavior and their attendant behavioral responses into an epidemiological context to better understand how diseases are transmitted. This framework should help improve policy responses to epidemic diseases by giving policymakers and health-care providers clear tools for thinking about how certain actions can influence the spread of disease transmission.

Contents

The main context through which this field emerged was the idea of prevalence-dependence, or disinhibition, which suggests that individuals change their behavior as the prevalence of a disease changes. However, economic epidemiology also encompasses other ideas, including the role of externalities, global disease commons and how individuals’ incentives can influence the outcome and cost of health interventions.

Strategic epidemiology is a branch of economic epidemiology that adopts an explicitly game theoretic approach to analyzing the interplay between individual behavior and population wide disease dynamics.[ citation needed ]

Prevalence-dependence

The spread of an infectious disease is a population-level phenomenon, but decisions to prevent or treat a disease are typically made by individuals who may change their behavior over the course of an epidemic, especially if their perception of risk changes depending on the available information on the epidemics [1] – their decisions will then have population-level consequences. For example, an individual may choose to have unsafe sex or a doctor may prescribe antibiotics to someone without a confirmed bacterial infection. In both cases, the choice may be rational from the individual's point of view but undesirable from a societal perspective.[ citation needed ]

Limiting the spread of disease at the population level requires changing individual behavior, which in turn depends on what information individuals have about the level of risk. When risk is low, people will tend to ignore it. However, if the risk of infection is higher, individuals are more likely to take preventive action. Moreover, the more transmissible the pathogen, the greater the incentive is to make personal investments for control. [2]

The converse is also true: if there is a lowered risk of disease, either through vaccination or because of lowered prevalence, individuals may increase their risk-taking behavior. This effect is analogous to the introduction of safety regulations, such as seatbelts in cars, which because they reduce the cost of an accident in terms of expected injury and death, could lead people to drive with less caution and the resulting injuries to nonoccupants and increased nonfatal crashes may offset some of the gains from the use of seatbelts. [2]

Prevalence-dependent behavior introduces a crucial difference with respect to the way individuals respond when the prevalence of a disease increases. If behavior is exogenous or if behavioral responses are assumed to be inelastic with respect to disease prevalence, the per capita risk of infection in the susceptible population increases as prevalence increases. In contrast, when behavior is endogenous and elastic, hosts can act to reduce their risks. If their responses are strong enough, they can reduce the average per capita risk and offset the increases in the risk of transmission associated with higher prevalence. [3] [4] [5] [6]

Alternatively, the waning of perceived risk, either through the diminution of prevalence or the introduction of a vaccine, may lead to increases in risky behavior. For example, models suggested that the introduction of highly active antiretroviral therapy (HAART), which significantly reduced the morbidity and mortality associated with HIV/AIDS, may lead to increases in the incidence of HIV as the perceived risk of HIV/AIDS decreased. [7]

Recent analysis suggests that an individual's likelihood of engaging in unprotected sex is related to their personal analysis of risk, with those who believed that receiving HAART or having an undetectable viral load protects against transmitting HIV or who had reduced concerns about engaging in unsafe sex given the availability of HAART were more likely to engage in unprotected sex regardless of HIV status. [8]

This behavioral response can have important implications for the timing of public interventions, because prevalence and public subsidies may compete to induce protective behavior. [9] In other words, if prevalence induces the same sort of protective behavior as public subsidies, the subsidies become irrelevant because people will choose to protect themselves when prevalence is high, regardless of the subsidy, and subsidies may not be helpful at the times when they are typically applied.[ citation needed ]

Although STDs are logical targets for examining the role of human behavior in a modeling framework, personal actions are important for other infectious diseases as well. The rapidity with which individuals reduce their contact rate with others during an outbreak of a highly transmissible disease can significantly affect the spread of the disease. [10] Even small reductions in the contact rate can be important, especially for diseases like influenza or severe acute respiratory syndrome (SARS). However, this may also affect policy planning for a biological attack with a disease such as smallpox.[ citation needed ]

Individual behavioral responses to interventions for non-sexually transmitted diseases are also important. For example, mass spraying to reduce malaria transmission can reduce the irritating effects of biting by nuisance mosquitoes and so lead to reduced personal use of bednets. [6] Economic epidemiology strives to incorporate these types of behavior responses into epidemiological models to enhance a model's utility in evaluating control measures.

Vaccination

Immunization represents a classic case of a social dilemma: a conflict of interest between the private gains of individuals and the collective gains of society, and prevalence-dependent behavior may have significant effects on vaccine policy formation. For instance, it was found in an analysis of the hypothetical introduction of a vaccine that would reduce (though not eliminate) the risk of contracting HIV, that individual levels of risk behavior were a significant barrier to eliminating HIV, as small changes in behavior could actually increase the incidence/prevalence of HIV, even if the vaccine were highly efficacious. [3] These results, as well as others, [11] [12] [13] [14] [15] [16] [17] may have contributed to a decision not to release existing semi-efficacious vaccines. [18]

An individual's self-interest and choice often leads to a vaccination uptake rate less than the social optimum as individuals do not take into account the benefit to others. In addition, prevalence dependent behavior suggests how the introduction of a vaccine may affect the spread of a disease. As the prevalence of a disease increases, people will demand to be vaccinated. As prevalence decreases, however, the incentive, and thus demand, will slacken and allow the susceptible population to increase until the disease can reinvade. As long as a vaccine is not free, either monetarily or through true or even perceived side effects, [19] [20] demand will be insufficient to pay for the vaccine at some point, leaving some people unvaccinated. If the disease is contagious, it could then begin spreading again among non-vaccinated individuals. Thus, it is impossible to eradicate a vaccine-preventable disease through voluntary vaccination if people act in their own self-interest. [21] [22] [23]

COVID-19

The idea of intertwining epidemiology and economics is relatively new with it first appearing in the early 1990s amidst the HIV/AIDS epidemic. Epidemiologists at the time realized that the disease was spread through one's decisions around sex, and reasoned that it must then be considered an endogenous variable within the Nash-Equilibrium, therefor linking this with economics as the outcomes could then be predicted. [24] Both Economics and Epidemiology however have influence from Utilitarianism in the form of, "doing the most good for the most people" or cost-benefit analysis as both fields of study hope to find net positives in the outcomes of their decisions. [25] However, the SARS-CoV-2 Pandemic and its fallout, has brought extremely relevant and timely data to researchers in this field.[ citation needed ]

From January 1, 2020, until December 4, 2022, there has been a centrally estimated 1,277,204 excess deaths relating from the COVID-19 pandemic, with a majority of deaths consisting of the disease. [26] Somewhat similar to John Snow discovering the vector for cholera through water pumps, epidemiologists were able to track community spread of COVID-19 through municipal wastewater systems. [27] These excess deaths are often thought of in terms of the human loss, the relationships and families members we no longer possess, but there is also an economic side to these excess mortalities. According to data from the World Bank, in 2021 the average GDP per capita for someone living in the United States was $69,288. [28] Despite the shortcomings of Gross Domestic Product in this scenario it serves as a decent variable to describe the lost economic output due to these excess deaths. Doing the arithmetic of excess deaths to GDP per capita we can see that the United States has lost around $88.5 billion in total output due to excess deaths during the COVID-19 Pandemic. The costs of the pandemic can also be extrapolated out into the cost of vaccine development/deployment, the cost of shutdowns or lack thereof (i.e. lost work/lost spending/low risk areas being closed), the extra health spending for patients that did not need it or could have avoided hospitalization if vaccinated, the fiscal stimulus provided by our government, the lost values to retirement accounts, and the broader effects of inflation.[ citation needed ]

Individuals have a something to lose as well when it comes to contracting the disease of SARS-CoV-2. For many hourly workers, this sick time off results in lost income and many salaried workers are able to do some work from a home office. Both of these situations can have positive and negative outcomes; whether it's getting additional assistance from the enhanced unemployment benefits for the greater part of 2021, or working from home with poor internet connectivity or no dedicated workspace. These headaches for many potentially contributed to the difference in reported incidence versus estimated-actual incidence rates of COVID-19 within a population. A 2020 cross-sectional study published in the JAMA Internal Medicine Journal performed blood testing on a convenience sample in 10 geographic sites across the United States and found that based on seroprevalence there were 10 times more cases than was being reported. [29]

Related Research Articles

<span class="mw-page-title-main">Epidemic</span> Rapid spread of disease affecting a large number of people in a short time

An epidemic is the rapid spread of disease to a large number of hosts in a given population within a short period of time. For example, in meningococcal infections, an attack rate in excess of 15 cases per 100,000 people for two consecutive weeks is considered an epidemic.

<span class="mw-page-title-main">Herd immunity</span> Concept in epidemiology

Herd immunity is a form of indirect protection that applies only to contagious diseases. It occurs when a sufficient percentage of a population has become immune to an infection, whether through previous infections or vaccination, thereby reducing the likelihood of infection for individuals who lack immunity.

The management of HIV/AIDS normally includes the use of multiple antiretroviral drugs as a strategy to control HIV infection. There are several classes of antiretroviral agents that act on different stages of the HIV life-cycle. The use of multiple drugs that act on different viral targets is known as highly active antiretroviral therapy (HAART). HAART decreases the patient's total burden of HIV, maintains function of the immune system, and prevents opportunistic infections that often lead to death. HAART also prevents the transmission of HIV between serodiscordant same-sex and opposite-sex partners so long as the HIV-positive partner maintains an undetectable viral load.

The spread of HIV/AIDS has affected millions of people worldwide; AIDS is considered a pandemic. The World Health Organization (WHO) estimated that in 2016 there were 36.7 million people worldwide living with HIV/AIDS, with 1.8 million new HIV infections per year and 1 million deaths due to AIDS. Misconceptions about HIV and AIDS arise from several different sources, from simple ignorance and misunderstandings about scientific knowledge regarding HIV infections and the cause of AIDS to misinformation propagated by individuals and groups with ideological stances that deny a causative relationship between HIV infection and the development of AIDS. Below is a list and explanations of some common misconceptions and their rebuttals.

HIV/AIDS has been a public health concern for Latin America due to a remaining prevalence of the disease. In 2018 an estimated 2.2 million people had HIV in Latin America and the Caribbean, making the HIV prevalence rate approximately 0.4% in Latin America.

<span class="mw-page-title-main">Epidemiology of HIV/AIDS</span> Epidemic of HIV/AIDS

The global epidemic of HIV/AIDS began in 1981, and is an ongoing worldwide public health issue. According to the World Health Organization (WHO), as of 2021, HIV/AIDS has killed approximately 40.1 million people, and approximately 38.4 million people are infected with HIV globally. Of these 38.4 million people, 75% are receiving antiretroviral treatment. There were about 770,000 deaths from HIV/AIDS in 2018, and 650,000 deaths in 2021. The 2015 Global Burden of Disease Study estimated that the global incidence of HIV infection peaked in 1997 at 3.3 million per year. Global incidence fell rapidly from 1997 to 2005, to about 2.6 million per year. Incidence of HIV has continued to fall, decreasing by 23% from 2010 to 2020, with progress dominated by decreases in Eastern Africa and Southern Africa. As of 2020, there are approximately 1.5 million new infections of HIV per year globally.

<span class="mw-page-title-main">Flu season</span> Recurring periods of influenza

Flu season is an annually recurring time period characterized by the prevalence of an outbreak of influenza (flu). The season occurs during the cold half of the year in each hemisphere. It takes approximately two days to show symptoms. Influenza activity can sometimes be predicted and even tracked geographically. While the beginning of major flu activity in each season varies by location, in any specific location these minor epidemics usually take about three weeks to reach its pinnacle, and another three weeks to significantly diminish.

<span class="mw-page-title-main">Meningococcal disease</span> Medical condition

Meningococcal disease describes infections caused by the bacterium Neisseria meningitidis. It has a high mortality rate if untreated but is vaccine-preventable. While best known as a cause of meningitis, it can also result in sepsis, which is an even more damaging and dangerous condition. Meningitis and meningococcemia are major causes of illness, death, and disability in both developed and under-developed countries.

<span class="mw-page-title-main">HIV/AIDS</span> Spectrum of conditions caused by HIV infection

Infection with HIV, a retrovirus, can be managed with treatment but without treatment can lead to a spectrum of conditions including AIDS.

<span class="mw-page-title-main">HIV/AIDS in Lesotho</span>

HIV/AIDS in Lesotho constitutes a very serious threat to Basotho and to Lesotho's economic development. Since its initial detection in 1986, HIV/AIDS has spread at alarming rates in Lesotho. In 2000, King Letsie III declared HIV/AIDS a natural disaster. According to the Joint United Nations Programme on HIV/AIDS (UNAIDS) in 2016, Lesotho's adult prevalence rate of 25% is the second highest in the world, following Eswatini.

<span class="mw-page-title-main">HIV/AIDS in Malawi</span> Impact of the immunodeficiency virus in the African nation

As of 2012, approximately 1,100,000 people in Malawi are HIV-positive, which represents 10.8% of the country's population. Because the Malawian government was initially slow to respond to the epidemic under the leadership of Hastings Banda (1966–1994), the prevalence of HIV/AIDS increased drastically between 1985, when the disease was first identified in Malawi, and 1993, when HIV prevalence rates were estimated to be as high as 30% among pregnant women. The Malawian food crisis in 2002 resulted, at least in part, from a loss of agricultural productivity due to the prevalence of HIV/AIDS. Various degrees of government involvement under the leadership of Bakili Muluzi (1994–2004) and Bingu wa Mutharika (2004–2012) resulted in a gradual decline in HIV prevalence, and, in 2003, many people living in Malawi gained access to antiretroviral therapy. Condoms have become more widely available to the public through non-governmental organizations, and more Malawians are taking advantage of HIV testing services.

<span class="mw-page-title-main">HIV/AIDS in Mozambique</span>

Mozambique is a country particularly hard-hit by the HIV/AIDS epidemic. According to 2008 UNAIDS estimates, this southeast African nation has the 8th highest HIV rate in the world. With 1,600,000 Mozambicans living with HIV, 990,000 of which are women and children, Mozambique's government realizes that much work must be done to eradicate this infectious disease. To reduce HIV/AIDS within the country, Mozambique has partnered with numerous global organizations to provide its citizens with augmented access to antiretroviral therapy and prevention techniques, such as condom use. A surge toward the treatment and prevention of HIV/AIDS in women and children has additionally aided in Mozambique's aim to fulfill its Millennium Development Goals (MDGs). Nevertheless, HIV/AIDS has made a drastic impact on Mozambique; individual risk behaviors are still greatly influenced by social norms, and much still needs to be done to address the epidemic and provide care and treatment to those in need.

HIV/AIDS is considered the deadliest epidemic in the 21st century. It is transmitted through sex, intravenous drug use and mother-to-child transmission. Zambia is experiencing a generalized HIV/AIDS epidemic, with a national HIV prevalence rate of 11.3% among adults ages 15 to 49 as of 2018. Per the 2000 Zambian census, the people affected by HIV/AIDS constituted 15% of the total population, amounting to one million, of which 60% were women. The pandemic results in increased number of orphans, with an estimated 600,000 orphans in the country. It was prevalent more in urban areas compared to rural and among all provinces, Copperbelt Province and Lusaka Province had higher occurrence.

<span class="mw-page-title-main">HIV/AIDS in Zimbabwe</span> Major public health issue

HIV and AIDS is a major public health issue in Zimbabwe. The country is reported to hold one of the largest recorded numbers of cases in Sub-Saharan Africa. According to reports, the virus has been present in the country since roughly 40 years ago. However, evidence suggests that the spread of the virus may have occurred earlier. In recent years, the government has agreed to take action and implement treatment target strategies in order to address the prevalence of cases in the epidemic. Notable progress has been made as increasingly more individuals are being made aware of their HIV/AIDS status, receiving treatment, and reporting high rates of viral suppression. As a result of this, country progress reports show that the epidemic is on the decline and is beginning to reach a plateau. International organizations and the national government have connected this impact to the result of increased condom usage in the population, a reduced number of sexual partners, as well as an increased knowledge and support system through successful implementation of treatment strategies by the government. Vulnerable populations disproportionately impacted by HIV/AIDS in Zimbabwe include women and children, sex workers, and the LGBTQ+ population.

<span class="mw-page-title-main">HIV/AIDS in Haiti</span>

With an estimated 150,000 people living with HIV/AIDS in 2016, Haiti has the most overall cases of HIV/AIDS in the Caribbean and its HIV prevalence rates among the highest percentage-wise in the region. There are many risk-factor groups for HIV infection in Haiti, with the most common ones including lower socioeconomic status, lower educational levels, risky behavior, and lower levels of awareness regarding HIV and its transmission.

NmVac4-A/C/Y/W-135 is the commercial name of the polysaccharide vaccine against the bacterium that causes meningococcal meningitis. The product, by JN-International Medical Corporation, is designed and formulated to be used in developing countries for protecting populations during meningitis disease epidemics.

Discrimination against people with HIV/AIDS or serophobia is the prejudice, fear, rejection, and stigmatization of people with HIV/AIDS. Marginalized, at-risk groups such as members of the LGBTQ+ community, intravenous drug users, and sex workers are most vulnerable to facing HIV/AIDS discrimination. The consequences of societal stigma against PLHIV are quite severe, as HIV/AIDS discrimination actively hinders access to HIV/AIDS screening and care around the world. Moreover, these negative stigmas become used against members of the LGBTQ+ community in the form of stereotypes held by physicians.

HIV prevention refers to practices that aim to prevent the spread of the human immunodeficiency virus (HIV). HIV prevention practices may be undertaken by individuals to protect their own health and the health of those in their community, or may be instituted by governments and community-based organizations as public health policies.

Pontiano Kaleebu is a Ugandan physician, clinical immunologist, HIV/AIDS researcher, academic and medical administrator, who is the executive director of the Uganda Virus Research Institute.

Fred Mhalu is a microbiologist and medical researcher from Tanzania. His main area of study revolves around infectious diseases and intervention. Ever since 1986, he has been a main contributor to the information about AIDS in Africa. As a co-coordinator of a Tanzanian-Swedish research collaboration called TANSWED, he was involved in many research projects that lead to multiple publications in medical journals. His more recent research on HIV/AIDS involves studying breast cancer in HIV prevalent areas, evaluating prevention of mother-to-child-transmission of HIV-1, and observing sexual behaviors of high risk populations for HIV-1.

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