Brown KA, Gubbay J, Hopkins J, et al. - A substantial transmission advantage of a novel variant of SARS-CoV-2, B.1.1.7, originally discovered in the UK, has led to its rapid overtaking of wild-type SARS-CoV-2 globally. Relative to the wild-type virus, this variant is identified to be 40% to 80% more transmissible and 35% more lethal. Researchers sought to estimate the spread of B.1.1.7 in the Greater Toronto Area, by tracking S-gene target failure (SGTF; a marker of B.1.1.7) prevalence between December 2020 and March 2021. They included 20,051 samples that tested positive for COVID-19 between December 15, 2020, and March 31, 2021, at Dynacare Laboratory Ontario. Of these samples, 4,692 had SGTF (23.4%). SGTF was identified to be a reliable marker of B.1.1.7. More rapid consistent growth was observed in prevalence of B.1.1.7 than preexisting variants, indicating raised transmissibility. As in the UK, an increase in the prevalence of B.1.1.7 occurred during a province-wide lockdown period (December 26, 2020, to February 9, 2021) when non-B.1.1.7 variants were effectively brought under control.