COVID-19 Vaccine

A COVID-19 vaccine is designed to induce immunity against SARS-CoV-2, the virus that causes coronavirus disease 2019, reducing the risk of severe illness, hospitalization and death. Vaccines were developed at an unprecedented pace after the first clinical trials began in March 2020, with the usual three phases of testing run in parallel to speed development, using both classical technologies such as inactivated virus or protein subunit and newer mRNA or viral vector platforms. Earlier research on the coronaviruses behind SARS and MERS had already advanced several vaccine platforms; Katalin Kariko and Drew Weissman won the 2023 Nobel Prize in Physiology or Medicine for developing effective mRNA vaccines against COVID-19. Major vaccines include the Pfizer-BioNTech and Moderna mRNA vaccines and the Novavax protein subunit vaccine, later updated into variant adapted booster doses as immunity from earlier doses waned over time. The vaccines are widely credited with reducing the spread and severity of COVID-19; one estimate published in the Journal of Paediatrics and Child Health put prevented deaths at between 14.4 and 19.8 million. By December 2020 more than 10 billion doses had been preordered, about half by high income countries holding 14 percent of the world's population, and by August 2024 more than 13 billion doses had been administered worldwide.