The effectiveness of population-wide, rapid antigen test based screening in reducing SARS-CoV-2 infection prevalence in Slovakia

Pavelka, M.; van Zandvoort, K.; Abbott, S.; Sherratt, K.; Majdan, M.; CMMID COVID-19 working group,; Institut Zdravotnych Analyz,; Jarcuska, P.; Krajci, M.; Flasche, S.; Funk, S.

Non-pharmaceutical interventions have been extensively used worldwide to limit the transmission of SARS-CoV-2, but they also place an enormous social and economic burden on populations . We report the results of recent mass testing for SARS-CoV-2 in Slovakia where rapid antigen tests were used to screen the whole population and to isolate infectious cases together with their household members. Prevalence of detected infections decreased by 58% (95% CI: 57-58%) within one week in the 45 counties that were subject to two rounds of mass testing. Adjusting for geographical clustering and differences in attendance rates and the epidemiological situation at the time of the first round, this changed to 61% (95% CI: 50-70%). Adjusting for an estimated growth rate in infections of 4.4% (1.1-6.9%) per day in the week preceding the mass testing campaign and the corresponding expected growth in infection prevalence, the estimated decrease in prevalence compared to a scenario of unmitigated growth was 70% (67-73%). Using a microsimulation model we find that this decrease can not be explained solely by infection control measures that were introduced in the weeks preceding the intervention, but requires the additional impact of isolation as well as quarantine of household members of those testing positive during the mass testing campaign.