Fig 3.

Severity of covid-19 during index hospital admission among adults with covid-19, by SARS-CoV-2 variant for unvaccinated and vaccinated patients. Disease severity was classified based on the highest severity level reached on the World Health Organization clinical progression scale, which ranged from hospital admission without supplemental oxygen (lowest level) to death (highest level). Among unvaccinated patients, severity was higher for the delta than alpha variant (adjusted proportional odds ratio 1.28, 95% confidence interval 1.11 to 1.46) and lower for the omicron than delta variant (0.61, 0.49 to 0.77). For each variant, severity was lower for vaccinated patients (two or three doses of an mRNA vaccine) than unvaccinated patients, including for alpha (adjusted proportional odds ratio 0.33, 0.23 to 0.49), delta (0.44, 0.37 to 0.51), and omicron (0.61, 0.44 to 0.85)