A novel variant of SARS-CoV-2, B.1.1.7, originally discovered in the UK, is rapidly overtaking wild-type SARS-CoV-2 globally,1 due to a substantial transmission advantage. This variant is estimated to be 40% to 80% more transmissible2 and 35% more lethal3 than the wild-type virus.
Deletion of amino acids 69 and 70 within the spike (S) gene of SARS-CoV-2 B.1.1.7, sometimes attributable to the N501Y mutation, can result in an undetectable S-gene target (S-gene target failure, SGTF) for some real-time reverse transcriptase polymerase chain reaction (RT-PCR) testing methods. A rapid increase in the proportion of SARS-CoV-2 samples with SGTF was identified in regions of England affected by B.1.1.7, and, after validation with whole genome sequencing, SGTF was determined to be a reliable marker of B.1.1.7 across the country.2
To quantify the spread of B.1.1.7 in the Greater Toronto Area, we tracked SGTF prevalence between December 2020 and March 2021.