Vaccine hesitancy in the context of "Anti-vaccination"

Vaccination is the administration of a vaccine to help the immune system develop immunity from a disease. Vaccines contain a microorganism or virus in a weakened, live or killed state, or proteins or toxins from the organism. In stimulating the body's adaptive immunity, they help prevent sickness from an infectious disease. When a sufficiently large percentage of a population has been vaccinated, herd immunity results. Herd immunity protects those who may be immunocompromised and cannot get a vaccine because even a weakened version would harm them.

The effectiveness of vaccination has been widely studied and verified. Vaccination is the most effective method of preventing infectious diseases; widespread immunity due to vaccination is largely responsible for the worldwide eradication of smallpox and the elimination of diseases such as polio and tetanus from much of the world. According to the World Health Organization (WHO), vaccination prevents 3.5–5 million deaths per year. A WHO-funded study by The Lancet estimates that, during the 50-year period starting in 1974, vaccination prevented 154 million deaths, including 146 million among children under age 5. However, some diseases have seen rising cases due to relatively low vaccination rates attributable partly to vaccine hesitancy.

COVID-19 vaccine hesitancy in the United States is the sociocultural phenomenon of individuals refusing or displaying hesitance towards receiving the COVID-19 vaccine. COVID-19 vaccine hesitancy in the United States can be considered as part of the broader history of vaccine hesitancy.

Anti-vaccine activism, which collectively constitutes the "anti-vax" movement, is a set of organized activities expressing opposition to vaccination. These collaborating networks often seek to increase vaccine hesitancy by disseminating vaccine misinformation and disinformation. As a social movement, it employs tools ranging from traditional news media to various forms of online communication. Activists have primarily—though not exclusively—focused on opposing childhood vaccination, and have sought to expand their influence from niche subgroups into national political debates.

Ideas that later coalesced into anti-vaccine activism predate vaccines themselves. The movement, along with fringe doctors, has propagated various myths and conspiracy theories, alongside misinformation and disinformation. These efforts have significantly increased vaccine hesitancy and influenced public policy regarding the ethical, legal, and medical aspects of vaccination. In contrast, there is no substantive debate or hesitancy within mainstream medical circles about the benefits of vaccination; the scientific consensus is "clear and unambiguous" in favor of vaccines. Despite this consensus, the anti-vaccine movement has been partially successful in distorting the public understanding of science in popular culture.