Rapid Increase in SARS-CoV-2 P.1 Lineage Leading to Codominance with B.1.1.7 Lineage, British Columbia, Canada, January–April 2021

Abstract

C haracterizing mutations in the severe acute re- spiratory syndrome coronavirus 2 (SARS-CoV-2) genome has led to the identifi cation of variants of concern (VOCs) on the basis of such criteria as increased transmissibility, clinical severity, effect on diagnostic testing, and reduced vaccine effi cacy (1-5). Globally, the B.1.1.7 (Alpha), B.1.351 (Beta), and P.1 (Gamma) lineages represented the 3 main actively circulating VOCs in late 2020 and early 2021 (6). B.1.1.7 was fi rst detected in England in September 2020 and progressed to become the dominant lineage in this setting within months (4,7). By early January 2021, >40 countries had documented B.1.1.7 cases, demonstrating rapid international spread (8). This lineage has been associated with an estimated 40%-90% increase in transmissibility (4,7), variable effects on clinical severity and mortality rates (5,9,10), and limited effect on vaccine effectiveness (11). In contrast, whereas B.1.351 and P.1 also emerged in fall 2020 and spread rapidly locally, initial evidence of international transmission beyond South Africa and Brazil was limited (8,12,13). The P.1 lineage poses concern given its associations with an estimated 70%-240% increase in transmissibility ( Limited evidence from Italy, where B.1.1.7 and P.1 lineages have cocirculated, has shown the potential for B.1.1.7 to surpass P.1 for dominant VOC status in a short timeframe (15; P. Stefanelli et al., unpub. data, https://www.medrxiv.org/content/10.1101/ 2021.04.06.21254923v1). However, recent evidence from the United States suggests that infection after vaccination might be attributed to variants characterized by such mutations as E484K, T95I, del142-144, and D614G (16). The SARS-CoV-2 spike E484K mutation, which is present in the P. 1 and B.1.351 lineages,

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