PROS1 and COVID-19: Several SARS-CoV-2 variants have emerged with the global COVID-19 pandemic.289 Fortunately, chimeras of the viral S protein were developed to prevent SARS-CoV-2 variants,270 and BNT162b2 and mRNA-1273 can still effectively prevent SARS-CoV-2 variants infections, including Delta (B.1.617.2), Alpha (B.1.1.7) and Gamma (P.1) variants in adults.272,290,291 Interestingly, there is a large difference in the mRNA dosages of COVID-19 mRNA vaccines.