Hospitalisation and mortality risk of SARS-COV-2 variant omicron sub-lineage BA.2 compared to BA.1 in England
Harriet Webster, Tommy Nyberg, Mary Sinnathamby, Nurin Abdul Aziz, Neil M. Ferguson, Giulia Seghezzo, Paula Blomquist, Jessica R. E. Bridgen, Meera Chand, Natalie Groves, Richard Myers, Russell Hope, Efejiro Ashano, Jamie Lopez Bernal, Daniela De Angelis, Gavin Dabrera, Anne M. Presanis, Simon Thelwall
Abstract
The Omicron variant of SARS-CoV-2 became the globally dominant variant in early 2022. A sub-lineage of the Omicron variant (BA.2) was identified in England in January 2022. Here, we investigated hospitalisation and mortality risks of COVID-19 cases with the Omicron sub-lineage BA.2 (n = 258,875) compared to BA.1 (n = 984,337) in a large cohort study in England. We estimated the risk of hospital attendance, hospital admission or death using multivariable stratified proportional hazards regression models. After adjustment for confounders, BA.2 cases had lower or similar risks of death (HR = 0.80, 95% CI 0.71-0.90), hospital admission (HR = 0.88, 95% CI 0.83-0.94) and any hospital attendance (HR = 0.98, 95% CI 0.95-1.01). These findings that the risk of severe outcomes following infection with BA.2 SARS-CoV-2 was slightly lower or equivalent to the BA.1 sub-lineage can inform public health strategies in countries where BA.2 is spreading.