There are currently numerous SARS-CoV-2 variants circulating in the U.S. that are thought to be able to partially evade immunity induced by prior infection and/or vaccination.

Multiple SARS-CoV-2 variants that have higher transmissibility, cause more severe disease, or that can evade immunity to some extent have been detected and tracked since late 2020.

Of particular concern to public health authorities in Virginia are SARS-CoV-2 variants circulating that are thought to be able to partially evade immunity induced by prior infection and/or vaccination.

The U.S. CDC currently defines three classes of SARS-CoV-2 variants. For our purposes, variants of concern and variants of high consequence are of particular interest:

• Variant of concern (VOC): “variant for which there is evidence of an increase in transmissibility, more severe disease (increased hospitalizations or deaths), significant reduction in neutralization by antibodies generated during previous infection or vaccination, reduced effectiveness of treatments or vaccines, or diagnostic detection failures.” As of the most recent CDC update on 27 April, there are five VOCs: B.1.1.7, P.1, B.1.351, B.1.427, and B.1.429.
• Variant of high consequence (VOHC): “variant of high consequence has clear evidence that prevention measures or medical countermeasures (MCMs) have significantly reduced effectiveness relative to previously circulating variants.” As of the most recent CDC update on 27 April, there are no VOHCs.

Of the five variants categorized under these categories (all five are VOCs), as of 27 April 2021 there are four that cause "reduced neutralization by convalescent and post-vaccination sera" (indicating they are able to partially evade immunity induced by infection and vaccination): P.1, B.1.351, B.1.427, and B.1.429. As of 27 April 2021, 8.8% of total available sequences in Virginia are one of these four VOCs: 2.3% B.1.351, 6.0% B.1.427/B.1.429, 0.5% P.1.