“The Variants Are Coming”: Emergence of SARS-CoV-2 Variant Lineages in the United States

Reviewed by James “Brad” Cutrell, MD FIDSA; UT Southwestern Medical School

Much of the public health and epidemiology community’s attention has shifted to the new circulating SARS-CoV-2 virus variants and their implications for vaccine efficacy and control of the pandemic. This report from the MMWR1 from the CDC by Galloway and colleagues summarized the spread of the B.1.1.7 SARS-CoV-2 variant, first reported in the United Kingdom, as of January 13, 2021 in the United States, by which time approximately 76 cases have been found in 12 states. As of January 25, those numbers have now increased to 293 cases in 24 states. They also present modeling data indicating that this variant, which is estimated to be about 50% more transmissible, could become the dominant variant in the US by as early as March 2021. Since this situation is “evolving” rapidly including the first case of the P.1 variant (first identified in Brazil) reported in Minnesota on January 25, 2021, it will be important for US efforts at genomic surveillance to ramp up quickly and to follow this story closely for further updates (see CDC website on emerging SARS-CoV-2 variants for the latest updates).2 


  1. Emergence of SARS-CoV-2 B.1.1.7 Lineage—United States, December 29,2020-January 12, 2021. Galloway SE, et al. MMWR January 22, 2021; 70 (3);95-99. https://www.cdc.gov/mmwr/volumes/70/wr/mm7003e2.htm
  2. CDC Website Emerging SARS-CoV-2 Variants https://www.cdc.gov/coronavirus/2019-ncov/more/science-and-research/scientific-brief-emerging-variants.html
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