In a recently published paper in Emerging Infectious Diseases, CITF-funded researchers, Dr. Agatha Jassem, Dr. Marc Romney, Dr. Mel Krajden and colleagues sought to summarize observations regarding variants of concern (VOCs) in British Columbia over a 16-week period from January to April 2021. On average, for the entire study period, 31.9% of positive tests were identified as VOCs, but monthly, the VOC infection rate increased from 0.93% in early February 2021 to 70% in April 2021.
The 16-week period was from January 3 to April 24, 2021. The authors highlighted the rapid spread of the Alpha and Gamma variants within the province. The Gamma variant swiftly increased after the Alpha variant was introduced into BC, becoming codominant with the latter.
- From January 2021 to April 2021, 31.9% of all positive SARS-CoV-2 cases were identified as infections with a VOC.
- Most VOC cases were among young adults with a median age of 33.
- Continued testing showed a rapid increase in VOC positivity increasing by >10% at the end of February 2021, >50% by the end of March 2021, and >70% by mid-April 2021.
- The proportion of cases caused by the Alpha and Gamma lineages rapidly increased, reaching about 35% between January and early April 2021. It’s estimated that the doubling rate was less than 1 week.
- While the Gamma lineage was identified in BC at the end of February, after the Alpha variant had already taken hold in the province, the Gamma variant rapidly spread to account for ~40% of VOCs by the end of March.
- The observed rise in the Gamma lineage was not hindered by vaccination efforts, as evidenced by similar proportions of VOC infection in vaccinated and unvaccinated individuals.
The BCCDC surveillance led to the detection of a rapid and substantial increase in the Gamma variant in BC. Gamma showed that it could compete with Alpha to be the dominant VOC in what has been shown to be the largest outbreak of the Gamma lineage outside of Brazil. The authors suggest further investigation into the biological and social factors that may have led to the increase in variants, as well as an examination of the clinical implications. It’s important to note that these data were captured prior to widespread vaccination campaigns.
Hogan CA, Jassem AN, Sbihi H, Joffres Y, Tyson JR, Noftall K, Taylor M, Lee T, Fjell C, Wilmer A, Galbraith J, Romney MG, Henry B, Krajden M, Galanis E, Prystajecky N, Hoang LMN. Rapid Increase in SARS-CoV-2 P.1 Lineage Leading to Codominance with B.1.1.7 Lineage, British Columbia, Canada, January-April 2021. Emerg Infect Dis. 2021 Aug 13;27(11). doi: 10.3201/eid2711.211190