SARS-CoV-2 antibody dynamics and transmission from community-wide serological testing in the Italian municipality of Vo'.
Ilaria DorigattiEnrico LavezzoLaura ManutoConstanze CiavarellaMonia PacentiCaterina BoldrinMargherita CattaiFrancesca SaluzzoElisa FranchinClaudia Del VecchioFederico CaldartGioele CastelliMichele NicolettiEleonora NiedduElisa SalvadorettiBeatrice LabellaLudovico FavaSimone GuglielmoMariateresa FascinaMarco GrazioliGualtiero AlvisiMaria Cristina VanuzzoTiziano ZupoReginetta CalandrinVittoria LisiLucia RossiIgnazio CastagliuoloStefano MeriglianoH Juliette T UnwinMario PlebaniAndrea PadoanAlessandra R BrazzaleStefano ToppoNeil M FergusonChristl Ann DonnellyAndrea CrisantiPublished in: Nature communications (2021)
In February and March 2020, two mass swab testing campaigns were conducted in Vo', Italy. In May 2020, we tested 86% of the Vo' population with three immuno-assays detecting antibodies against the spike and nucleocapsid antigens, a neutralisation assay and Polymerase Chain Reaction (PCR). Subjects testing positive to PCR in February/March or a serological assay in May were tested again in November. Here we report on the results of the analysis of the May and November surveys. We estimate a seroprevalence of 3.5% (95% Credible Interval (CrI): 2.8-4.3%) in May. In November, 98.8% (95% Confidence Interval (CI): 93.7-100.0%) of sera which tested positive in May still reacted against at least one antigen; 18.6% (95% CI: 11.0-28.5%) showed an increase of antibody or neutralisation reactivity from May. Analysis of the serostatus of the members of 1,118 households indicates a 26.0% (95% CrI: 17.2-36.9%) Susceptible-Infectious Transmission Probability. Contact tracing had limited impact on epidemic suppression.