A COVID‑19 vaccine is a biotechnology product intended to provide acquired immunity against coronavirus disease 2019 (COVID‑19). As of August 2020, there were 231 vaccine candidates in development,[1][2] although no candidate has completed clinical trials to prove its safety and efficacy. In August, at least 25 vaccine candidates were in clinical trials, with 6 beginning Phase III and 19 still in Phase I–II.[1][2][3]

Previous work to develop a vaccine against the coronavirus diseases SARS and MERS established considerable knowledge about the structure and function of coronaviruses – which accelerated rapid development during early 2020 of varied technology platforms for a COVID‑19 vaccine.[4]

The Coalition for Epidemic Preparedness Innovations (CEPI), which is organizing a US$2 billion worldwide fund for rapid investment and development of vaccine candidates,[5] indicated in April that a vaccine may be available under emergency use protocols in less than twelve months or by early 2021.[6] On 4 May 2020, the WHO organized a telethon which received US$8.1 billion in pledges from forty countries to support rapid development of vaccines to prevent COVID‑19 infections.[7] At the same time, the WHO also announced the deployment of an international "Solidarity trial" for simultaneous evaluation of several vaccine candidates reaching Phase II–III clinical trials.[8]