摘要
As of August 30,2021,COVID-19 has caused more than 216 million infections and 4.49 million deaths worldwide,with 0.58 million new cases[1].Because the COVID-19 vaccine is distributed gradually and widely,the development of the global epidemic has been prevented to some extent,but the emergence of SARS-CoV-2 variants makes us worried.The alpha(B.1.1.7),beta(B.1.351),gamma(P.1)and delta(B.1.617)strains have been named variants of concern by the WHO[2].The SARS-CoV-2 variants have increased in transmissibility and virulence,leading to higher morbidity and mortality.