Secondary attack rate of COVID-19 in shared households in Slovakia.

Abstract

The objective of this study was to estimate the secondary attack rate in unvaccinated members of households of two regions in the Slovak Republic for the period November 2020 ‒ April 2021. SARS-CoV-2 infection poses ahigh risk of transmission in close-contact indoor settings, such as households. The household transmissibility of SARS-CoV-2 varies widely across countries. We included 278 households for SARS-CoV-2 transmission analysis. We calculated the secondary attack rate (SAR). We assessed sex, level of disease severity and means of isolation during infection of index cases as determinants of disease transmissibilityRESULTS: The secondary attack rate in 278 households was estimated at 63.7% (95%CI: 58.2‒66.7%). The SARs were different by sex (60.2% in females, 67.5% in males). The highest SAR was observed in the households of asymptomatic cases (77.8%), followed by moderate severity (66.5%), hospital admissions (63.2%) and mild disease (58.2%). We found ahigh household secondary attack rate in two regions of Slovakia in the period when Alpha variant (B.1.1.7) of SARS-CoV-2 was dominant in the country. The results highlight the importance of monitoring transmission dynamics (Tab. 1, Fig. 1, Ref. 12). Text in PDF www.elis.sk Keywords: COVID-19, secondary attack rate, Slovak Republic, households.