How COVID‑19 vaccines work. The video shows the process of vaccination, from injection with RNA or viral vector vaccines, to uptake and translation, and on to immune system stimulation and effect.
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).
Knowledge about the structure and function of previous coronaviruses causing diseases like severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS) accelerated the development of various vaccine platforms in early 2020.[1] In 2020, the first COVID‑19 vaccines were developed and made available to the public through emergency authorizations[2] and conditional approvals.[3][4] However, immunity from the vaccines wanes over time, requiring people to get booster doses of the vaccine to maintain protection against COVID‑19.[2]
The COVID‑19 vaccines are widely credited for their role in reducing the spread of COVID‑19 and reducing the severity and death caused by COVID‑19.[2][5] Many countries implemented phased distribution plans that prioritized those at highest risk of complications, such as the elderly, and those at high risk of exposure and transmission, such as healthcare workers.[6][7]
Common side effects of COVID‑19 vaccines include soreness, redness, rash, inflammation at the injection site, fatigue, headache, myalgia (muscle pain), and arthralgia (joint pain), which resolve without medical treatment within a few days.[8][9] COVID‑19 vaccination is safe for people who are pregnant or are breastfeeding.[10]
As of August 2024[update], 13.72billion doses of COVID‑19 vaccines have been administered worldwide, based on official reports from national public health agencies.[11] By December 2020, more than 10 billion vaccine doses had been preordered by countries,[12] with about half of the doses purchased by high-income countries comprising 14% of the world's population.[13]