Risk of severe COVID-19 from the Delta and Omicron variants in relation to vaccination status, sex, age and comorbidities- surveillance results from southern Sweden, July 2021 to January 2022

We compared the risk of severe COVID-19 during two periods 2021 and 2022 when Delta and Omicron, respectively, were the dominating virus variants in Scania county, Sweden. We adjusted for differences in sex, age, comorbidities, prior infection and vaccina-tion. Risk of severe disease from Omicron was mark-edly lower among vaccinated cases. It was also lower among the unvaccinated but remained high (> 5%) for older people and middle-aged men with two or more comorbidities. Efforts to increase vaccination uptake should continue.

Automated summary

We compared the risk of severe COVID-19 between the periods of 2021 and 2022 in Scania county, Sweden, when Delta and Omicron were the dominant virus variants. Adjusting for factors like sex, age, comorbidities, prior infection, and vaccination, we found that the risk of severe disease from Omicron was significantly lower among vaccinated cases. It was also lower among the unvaccinated population, but remained high (> 5%) for older individuals and middle-aged men with multiple comorbidities. Efforts to increase vaccination uptake should continue.