Seroprevalence of SARS-CoV-2-specific antibodies in the town of Ariano Irpino (Avellino, Campania, Italy): a population-based study

Cerino, Pellegrino; Coppola, Annachiara; Volzone, Palmiero; Pizzolante, Antonio; Pierri, Biancamaria; Atripaldi, Luigi; Zollo, Massimo; Capasso, Mario; Ascierto, Paolo Antonio; Triassi, Maria; Brambilla, Gianfranco; Perrella, Alessandro; Bruzzese, Dario; Buonerba, Carlo

The Italian municipality of Ariano Irpino (Avellino, Campania, Italy) was locked down by the regional authorities from March until April 2020 after several citizens tested positive for SARS coronavirus 2 (SARS-CoV-2). A serological mass screening campaign targeting the Ariano Irpino population using the Roche Cobas Elecsys anti-SARS-CoV-2 assay was organized by the Zoo-Prophylactic Institute of Southern Italy (Portici, Italy) and conducted in cooperation with the Local Health Unit (Azienda Sanitaria Locale – ASL – Avellino, Avellino, Italy), the Department of Public Health of University Federico II (Naples, Italy) and Department of Health Services of Azienda Ospedaliera dei Colli-Cotugno and Monaldi Hospital (Naples, Italy) in May 2020. A total of 13,218 asymptomatic individuals were reviewed in this analysis. A total of 738 citizens tested positive for anti-SARS-CoV-2 antibodies (398 females, 340 males). The overall prevalence in the sample was 5.6% (95% CI: 5.2–6.0). Among seropositive citizens, 101 cases tested positive on RT-PCR (0.76% of the overall population). Among citizens aged 14–18, 18–65 and >65 years, the seroprevalence was equal to 6.1 (95% CI: 4.1–8.7), 5.6 (95% CI: 5.1–6.1) and 4% (95% CI: 3.3–4.8), respectively. In the pediatric cohort (<14 years old), seroprevalence was 13% (95% CI: 10.2–16.2). A serological-based screening strategy could be a cost-effective public health intervention to tackle the COVID-19 pandemic.