Challenge of COVID-19 vaccine discovery & development

COVID-19 (Coronavirus Disease 2019) is novel viral pneumonia caused by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2, also called 2019nCoV). The world is in midst of the COVID-19 pandemic. Effective vaccines are needed to halt the spread of the SARS-CoV-2 pandemic. Based on the data from WTO, there are 52 COVID-19 vaccines in clinical stage (Supplementary Table 1.) and 162 COVID-19 vaccine candidates in pre-clinical stage (Supplementary Table 2.) 2 mRNA vaccines, the BNT162b2 from Pfizer & BioNTech and the mRNA-1273 from Moderna, have recently been issued the emergency use authorization (EUA) by the U.S. Food and Drug Administration (FDA) for the prevention of COVID-19 in individuals 16 years of age and older.

The efficacy and safety of COVID-19 vaccine candidates need carefully investigated, from pre-clinical, clinal stage to a long time after BLA. There are 2 important items here:

Firstly, the coronavirus is kept accumulated mutating. The most important mutation occurs in SARS-CoV-2 (2019nCoV) Spike protein (SARS-CoV-2 S protein). The SARS-CoV-2 (2019nCoV) Spike mediates binding and entry into host cells and is a major target of neutralizing antibodies. Most of the COVID-19 vaccines focus on spike protein^1,4-6.

Different SARS-CoV-2 lineages with diverse Spike protein mutant variants may yield a heavy impact on the course of the pandemic^2-3. The United Kingdom (UK) has faced a rapid increase in COVID-19 cases caused by a novel SARS-COV-2 (2019nCOV) lineage, the B.1.1.7 lineage, which carries a larger than a usual number of coronavirus genetic changes^7-8, particularly in the SARS-CoV-2 spike protein（Table 1）⁷.