In a study recently published on the preprint server, the effectiveness of coronavirus disease 2019 (COVID-19) vaccines against the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron variant was studied. The study concluded that two vaccine doses are highly ineffective against infection by the Omicron variant.
Since the first case of the SARS-CoV-2 Omicron variant was detected in Ontario, Canada, a sharp increase in SARS-CoV-2 infections was noted, even in fully vaccinated individuals. Reduction in against the Omicron variant after individuals have received both their second and third vaccine doses has already been reported in many studies. The current study aims to estimate vaccine effectiveness (VE) against the SARS-CoV-2 Omicron variant over varying periods of time after vaccination.