Overall health of the population of the United States
The World Health Organization defines health as "a state of complete physical, mental and social well-being". Average life expectancy at birth was 78.7 in 2017. Heart diseases are responsible for the greatest number of deaths in the United States. 
All 50 states in the U.S. require immunization for children in order to enroll in public school, but various exemptions are available by state (such as for religious reasons). Immunizations are often compulsory for military enlistment in the United States. 
It is estimated that one in five adults in the US lives with a mental health disorder, with 50% receiving treatment for their condition. Sexually transmitted infections impact the health of approximately 19 million yearly. The two most commonly reported infections include chlamydia and gonorrhea.
In the context of ensuring the continuation of medical services, concerns of a current and future shortage of medical doctors due to the supply and demand for physicians in the United States have come from multiple entities including professional bodies such as the American Medical Association (AMA), with the subject being analyzed as well by the American news media in publications such as "Forbes", "The Nation", and "Newsweek". In the 2010s, a study released by the Association of American Medical Colleges (AAMC) titled "The Complexities of Physician Supply and Demand: Projections From 2019 to 2034" specifically projected a shortage of between 37,800 and 124,000 individuals within the following two decades, approximately.
Sexually transmitted infections.
Sexually transmitted infections (STIs) remain a major public health challenge in the United States. CDC estimates that there are approximately 19 million new STIs yearly. The country experienced a reduction in "reported" STIs early in the COVID-19 pandemic, likely due to reduction in care devoted to them, but rates have rebounded in ensuing years. The two most commonly reported infections with 1.5 million total cases (2009) are chlamydia and gonorrhea. Adolescent girls (15–19 years of age) and young women (20–24 years of age) are especially affected by these two diseases.
Chlamydia.
Chlamydia remains the most commonly reported infection in the United States. There were more than 1.2 million cases of chlamydia (1,244,180) reported to CDC in 2009, the largest number of cases ever reported to CDC for any condition. The rate reached 1.6 million cases in 2020, which was actually a decrease from 2016.
Gonorrhea.
There were 301,174 reported cases of gonorrhea in 2009 (10 percent less than in 2008), making gonorrhea the second most commonly reported infection in the U.S. In 2009, the gonorrhea rate for women was slightly higher than for men. By 2020, there were more than twice as many cases reported, about 678,000, a 45% increase from 2016.
Syphilis.
In 2009, there were 13,997 reported cases of primary and secondary syphilis — the most infectious stages of the disease — the highest number of cases since 1995 and an increase over 2007 (11,466 cases). The number of cases was ten times the 2009 figure by 2020, about 134,000, more than a 50% increase from 2016.
According to a report from the Centers for Disease Control and Prevention on April 11, 2023, syphilis is now at a rate not seen since the 1950s, increasing by about 30 percent between 2020 and 2021, a big jump from syphilis rates recorded in the early 2000s, where only about 30,000 cases were recorded each year.
Specific outbreaks, plagues, and epidemics in the United States.
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Vaccination.
The Advisory Committee on Immunization Practices makes scientific recommendations which are generally followed by the federal government, state governments, and private health insurance companies.
All 50 states in the U.S. mandate immunizations for children in order to enroll in public school, but various exemptions are available depending on the state. All states have exemptions for people who have medical contraindications to vaccines, and all states except for California, Maine, Mississippi, New York, and West Virginia allow religious exemptions, while sixteen states allow parents to cite personal, conscientious, philosophical, or other objections. An increasing number of parents are using religious and philosophical exemptions; researchers have cited this increased use of exemptions as contributing to loss of herd immunity within these communities, and hence an increasing number of disease outbreaks.
The growing trend of vaccine hesitancy is seen as one of the key factors behind the resurgence of vaccine-preventable diseases, particularly measles. Studies show that localized outbreaks have occurred in communities with high rates of exemptions, where vaccine coverage is below the critical threshold for herd immunity. For instance, the 2014-2015 measles outbreak in the United States, which primarily affected unvaccinated children, highlighted the vulnerability of these communities. Additionally, the increasing prevalence of misinformation on social media platforms has exacerbated vaccine hesitancy, making it a public health challenge. As a result, some states, such as California, have implemented stricter vaccination requirements to curb these trends. 
The American Academy of Pediatrics (AAP) advises physicians to respect the refusal of parents to vaccinate their child after adequate discussion, unless the child is put at significant risk of harm (e.g., during an epidemic, or after a deep and contaminated puncture wound). Under such circumstances, the AAP states that parental refusal of immunization constitutes a form of medical neglect and should be reported to state child protective services agencies.
See Vaccination schedule for the vaccination schedule used in the United States.
Immunizations are often compulsory for military enlistment in the U.S.
All vaccines recommended by the U.S. government for its citizens are required for green card applicants. This requirement stirred controversy when it was applied to the HPV vaccine in July 2008 because of the cost of the vaccine, and because the other thirteen required vaccines prevent diseases which are spread by a respiratory route and are considered highly contagious, while HPV is only spread through sexual contact. In November 2009, this requirement was canceled.
The controversy surrounding mandatory vaccination has often revolved around the balance between public health measures and individual rights. Ethical debates regarding vaccine mandates have been influenced by concerns over bodily autonomy and parental rights. However, numerous studies emphasize that vaccination mandates are essential for protecting public health and preventing the spread of infectious diseases. Mandatory vaccination laws are associated with higher immunization rates and lower incidence of vaccine-preventable diseases, supporting the argument that such laws are effective public health interventions. 
Schools.
The United States has a long history of school vaccination requirements. The first school vaccination requirement was enacted in the 1850s in Massachusetts to prevent the spread of smallpox. The school vaccination requirement was put in place after the compulsory school attendance law caused a rapid increase in the number of children in public schools, increasing the risk of smallpox outbreaks. The early movement towards school vaccination laws began at the local level including counties, cities, and boards of education. By 1827, Boston had become the first city to mandate that all children entering public schools show proof of vaccination. In addition, in 1855 the Commonwealth of Massachusetts had established its own statewide vaccination requirements for all students entering school; this influenced other states to implement similar statewide vaccination laws in schools as seen in New York in 1862, Connecticut in 1872, Pennsylvania in 1895, and later the Midwest, South and Western US. By 1963, 20 states had school vaccination laws.
These school vaccination resulted in political debates throughout the United States, as those opposed to vaccination sought to overturn local policies and state laws. An example of this political controversy occurred in 1893 in Chicago, where less than 10 percent of the children were vaccinated despite the twelve-year-old state law. Resistance was seen at the local level of the school district as some local school boards and superintendents opposed the state vaccination laws, leading the state board health inspectors to examine vaccination policies in schools. Resistance proceeded during the mid-1900s and in 1977 a nationwide Childhood Immunization Initiative was developed with the goal of increasing vaccination rates among children to 90% by 1979. During the two-year period of observation, the initiative reviewed the immunization records of more than 28 million children and vaccinated children who had not received the recommended vaccines.
This push for increased immunization rates has been supported by research showing that childhood vaccination initiatives, such as the 1977 Childhood Immunization Initiative, led to a significant reduction in vaccine-preventable diseases like measles, rubella, and diphtheria. The initiative, along with other vaccination campaigns, contributed to the widespread acceptance of immunizations as a standard practice in American schools. Today, school vaccination requirements continue to be a major strategy for preventing outbreaks of infectious diseases. However, the rise in vaccine hesitancy and exemptions has undermined some of the progress made, requiring public health officials to rethink vaccination policies in schools. 
In 1922 the constitutionality of childhood vaccination was examined in the Supreme Court case "Zucht v. King". The court decided that a school could deny admission to children who failed to provide a certification of vaccination for the protection of the public health. In 1987, a measles epidemic occurred in Maricopa County, Arizona, and another court case, "Maricopa County Health Department vs. Harmon", examined the arguments of an individual's right to education over the state's need to protect against the spread of disease. The court decided that it is prudent to take action to combat the spread of disease by denying un-vaccinated children a place in school until the risk for the spread of measles has passed. 
Schools in the United States require an updated immunization record for all incoming and returning students. While all states require an immunization record, this does not mean that all students must get vaccinated. Opt-out criteria are determined at a state level. In the United States, opt-outs take one of three forms: medical, in which a vaccine is contraindicated due to a component ingredient allergy or existing medical condition; religious; and personal philosophical opposition. As of 2019, 46 states allow religious exemptions, with some states requiring proof of religious membership. Only Mississippi, West Virginia, California and New York do not permit religious exemptions. 18 states allow personal or philosophical opposition to vaccination.
Over the last decade vaccination rates have been declining in the United States. Although the rate is fairly limited on a larger scale, vaccine-preventable disease outbreaks are occurring in pockets across the U.S. “In 2012, exemption rates ranged from a low of approximately 0.45 percent in New Mexico, to a high of 6.5 percent in Oregon. The outbreaks have significant correlations with unvaccinated children, and state policy exemption processes. California, which is currently in the process of changing its state exemption policies, dealt with a 2015 measles outbreak stemming from the popular Disneyland park. Significantly, most of the afflicted were unvaccinated, which eventually spread to over 17 separate states across the U.S.
Old age.
In 1790, people over the age of 65 were less than 2% of the American population. In 2017, they were about 14%.
Impact of climate change on health.
Climate change continues to affect every country in the world and the United States is no exception. In the U.S. the average temperature has increased between 1.3°F - 1.9°F since record keeping began in 1895, with most of the increase having occurred since about 1970. Additionally, hurricanes and winter storms have increased in both intensity and frequency and the length of the frost-free season has been increasing nationally since the 1980s, affecting ecosystems and agriculture. Climate change and climate variability has many potential effects on the health of Americans. It can exacerbate existing health threats or create new public health challenges through a variety of pathways. Although all Americans will face some health effect from climate change, certain individuals are more vulnerable than others due to levels of exposure, sensitivity, and ability to adapt (See Table).
The Center for Disease Control (CDC) has identified nine national health topics relating to climate change.
1. Air pollution
Ground-level ozone (a key component of smog) is associated with multiple health problems. Examples include diminished lung function, increased hospital admissions and emergency room visits for asthma, and increases in premature deaths. Health-related costs of the current effects of ozone air pollution exceeding national standards have been estimated at $6.5 billion (in 2008 U.S. dollars) nationwide, based on a U.S. assessment of health impacts from ozone levels during 2000–2002. 
2. Allergens and pollen
Climate change will potentially lead to shifts in precipitation patterns, more frost-free days, warmer seasonal air temperatures, and more carbon dioxide (CO2) in the atmosphere. These