Vaccines for COVID-19

Abstract

Since the emergence of COVID-19, caused by the SARS-CoV-2 virus at the end of 2019, there has been an explosion of vaccine development. By 24 September 2020, a staggering number of vaccines (more than 200) had started preclinical development, of which 43 had entered clinical trials, including some approaches that have not previously been licensed for human vaccines. Vaccines have been widely considered as part of the exit strategy to enable the return to previous patterns of working, schooling and socializing. Importantly, to effectively control the COVID-19 pandemic, production needs to be scaled-up from a small number of preclinical doses to enough filled vials to immunize the world's population, which requires close engagement with manufacturers and regulators. It will require a global effort to control the virus, necessitating equitable access for all countries to effective vaccines. This review explores the immune responses required to protect against SARS-CoV-2 and the potential for vaccine-induced immunopathology. We describe the profile of the different platforms and the advantages and disadvantages of each approach. The review also addresses the critical steps between promising preclinical leads and manufacturing at scale. The issues faced during this pandemic and the platforms being developed to address it will be invaluable for future outbreak control. Nine months after the outbreak began we are at a point where preclinical and early clinical data are being generated for the vaccines; an overview of this important area will help our understanding of the next phases.

Fig. 1

SARS‐CoV‐2 virus. The SARS‐CoV‐2 encodes 11 ORF, ORF1a and ORF1b are polyproteins that are cleaved into multiple individual proteins. The spike (S) protein is the major antigenic determinant, coat is made of spike (S), membrane (M) and envelope (E) proteins. The RNA in encapsulated with the nucleocapsid (N) protein). Created with Biorender.com

Fig. 2

Vaccine platforms; Over 200 different vaccines are in development. They loosely group into protein, inactivated, VLP, viral vector, mRNA, self‐amplifying RNA, DNA and live attenuated vaccines. Created with Biorender.com