Reference:
Lyngse, F. P., Mortensen, L. H., Denwood, M. J., Christiansen, L. E., Møller, C. H., Skov, R. L., … & Krause, T. G. (2021). SARS-CoV-2 Omicron VOC transmission in Danish households. medRxiv. https://doi.org/10.1101/2021.12.27.21268278
Summary:
This study investigates the transmission of the Omicron variant of SARS-CoV-2 within Danish households, comparing it to the Delta variant. It analysed data from 11,937 households, identifying 6,397 secondary infections over a 1-7 day follow-up. The secondary attack rate (SAR) was significantly higher for Omicron at 31%, compared to 21% for Delta. Notably, unvaccinated individuals had similar SARs for both variants, while fully vaccinated and booster-vaccinated individuals showed increased susceptibility to Omicron, indicating its immune evasion capabilities. The findings suggest that the Omicron variant spreads more effectively among vaccinated individuals than Delta, primarily due to immune evasion rather than inherent transmissibility. The study underscores the importance of booster vaccinations in reducing transmission, although they may not be sufficient to curb the Omicron variant’s spread long-term.