New sars-cov-2 variants challenge vaccines protection

Abstract

By the end of February 2021, roughly 115 million people worldwide had been infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and more than 2.5 million had died. Uneasily, the coronavirus disease 2019 (COVID-19) pandemic is increasingly resembling the tragic 1918 influenza pandemic that killed more than 50 million people a century ago.