How will emerging SARS-CoV-2 variants impact herd immunity?
Giuseppe Lippi, Brandon Michael Henry
Abstract
Several lines of evidence now attest that a considerable number of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants are circulating in many countries around the globe, thus reinforcing the need of continuous genomic surveillance to identify introduction events, monitor the diffusion of these new strains and assess their clinical and healthcare impact (1). New viral variants can be defined as “of concern” when their infectivity and/or pathogenicity and/or capacity to escape immune system recognition are significantly higher than the original “wild-type” strain, thus consequently boosting virus spread within the population, enhancing the risk of developing more severe illness and/or even causing epidemic rebounds. As specifically concerns SARS-CoV-2, at least three such variants have been identified in several different territories by both the European Centre for Disease Control and Prevention (ECDC) (2) and the US Centers for Disease Control and Prevention (CDC) (3) to-date.