COVID-19 Vaccine | news updates about COVID-19 VACCINE
A COVID‑19 vaccine is a vaccine intended to provide acquired immunity against COVID-19. Prior to the COVID-19 pandemic, work to develop a vaccine against the coronavirus diseases SARS and MERS had established knowledge about the structure and function of coronaviruses, which accelerated development during early 2020 of varied technology platforms for a COVID‑19 vaccine.
By mid-December 2020, 57 vaccine candidates were in clinical research, including 40 in Phase I–II trials and 17 in Phase II–III trials. In Phase III trials, several COVID-19 vaccines demonstrated efficacy as high as 95% in preventing symptomatic COVID-19 infections. National regulatory authorities have approved six vaccines for public use: two RNA vaccines (tozinameran from Pfizer–BioNTech and mRNA-1273 from Moderna), two conventional inactivated vaccines (BBIBP-CorV from Sinopharm and CoronaVac from Sinovac), and two viral vector vaccines (Gam-COVID-Vac from the Gamaleya Research Institute and AZD1222 from the University of Oxford and AstraZeneca).
Many countries have implemented phased distribution plans that prioritize those at highest risk of complications, such as the elderly, and those at high risk of exposure and transmission, such as healthcare workers.[2] As of 8 January 2021, 17.7 million doses of COVID-19 vaccine had been administered worldwide based on official reports from national health agencies.[3] Pfizer, Moderna, and AstraZeneca predicted a manufacturing capacity of 5.3 billion doses in 2021, which could be used to vaccinate about 3 billion people (as the vaccines require two doses for a protective effect against COVID-19). By December, more than 10 billion vaccine doses had been preordered by countries,[4] with about half of the doses purchased by high-income countries comprising only 14% of the world's population.
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