Infections with the Omicron SARS-CoV-2 variant are rapidly increasing worldwide. Among 174,349 SARS-CoV-2-infected individuals (≥ 12 years), we observed an increased risk of S gene target failure, predictive of the Omicron variant, in vaccinated (odds ratio (OR): 3.6; 95% confidence interval (CI): 3.4-3.7) and previously infected individuals (OR: 4.2; 95% CI: 3.8-4.7) compared with infected naïve individuals. This suggests vaccine- or infection-induced immunity against SARS-CoV-2 infections is less effective against the Omicron than the Delta variant.
Keywords: SARS-CoV-2 Omicron Variant of Concern Vaccine escape; air-borne infections; epidemiology; laboratory; severe acute respiratory syndrome - SARS; vaccines and immunisation; viral infections.