A COVID‑19 vaccine is a vaccine intended to provide acquired immunity against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus that causes coronavirus disease 2019 (COVID‑19).
Evidence from vaccine use during the pandemic shows vaccination can reduce infection and is most effective at preventing severe COVID-19 symptoms and death, but is less good at preventing mild COVID-19. Efficacy wanes over time but can be maintained with boosters.[217] In 2021 the CDC reported that unvaccinated people were 10 times more likely to be hospitalized and 11 times more likely to die than fully vaccinated people.
