† These authors contributed equally.
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections were
first detected in Wuhan, China in December 2019 and resulted in a worldwide
pandemic in 2020. SARS-CoV-2 infections totalled more than 180 million with 3.9
million deaths as of June 24, 2021. Tremendous research efforts have resulted in
the development of at least 64 vaccine candidates that have reached Phase I to
III clinical trials within 14 months. The primary efficacy endpoint for a random
placebo-controlled clinical trial of a COVID-19 vaccine to be approved by US FDA
should confer at least 50% protection against COVID-19. Three COVID-19 vaccines
(BNT162b2, mRNA-1273 and Sputnik V) in clinical Phase III trials have now
achieved