Serology- and PCR-based cumulative incidence of SARS-CoV-2 infection in adults in a successfully contained early hotspot (CoMoLo study), Germany, May to June 2020

Three months after a coronavirus disease (COVID-19) outbreak in Kupferzell, Germany, a population-based study (n = 2,230) found no RT-PCR-positives. IgG-ELISA seropositivity with positive virus neutralisation tests was 7.7% (95% confidence interval (Cl): 6.5-9.1) and 4.3% with negative neutralisation tests. We estimate 12.0% (95% Cl: 10.4-14.0%) infected adults (24.5% asymptomatic), six times more than notified. Full hot-spot containment, confirms the effectiveness of prompt protection measures. However, 88% nalve adults are still at high COVID-19 risk.