SARS-CoV-2 Targets and COVID-19 Vaccines

Abstract

Coronavirus disease-2019 (COVID-19) vaccines are being used across the globe to reduce the risk of developing COVID-19, stop the transmission of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), and end the pandemic. To address this, a massive global effort is underway for development of COVID-19 vaccines. As of September 2021, the World Health Organization (WHO) has documented 331 COVID-19 vaccine candidates, and 107 are in clinical evaluation, with 8 in Phase IV and 30 in Phase III clinical trials (WHO; COVID-19 vaccine tracker). At least 13 different vaccines are being issued for emergency use authorization. Specifically, the goal is to produce protective immunity to SARS-CoV-2 infection by stimulating an immune response to either the whole virus, viral protein, or nucleic acid products. The spike (S) proteins of SARS-CoV-2 that give the characteristic “corona” appearance of this family of viruses has emerged as an effective target for vaccines. Other viral candidates that are being developed also aim to produce immunity for COVID-19. In this review, we describe the different vaccine platforms, target candidates for vaccines, and their progress in COVID-19 vaccine development. This is critical since newly discovered SARS-CoV-2 variants of interest require understanding of how vaccines may provide the most effective long-term protection against infection.