Dynamics of the SARS-CoV-2 epidemic in the earliest-affected areas in Italy: 1 Mass screening for SARS-CoV-2 serological positivity (SARS-2-SCREEN).

BackgroundSeveral municipalities in the Lombardy Region have been affected by the SARS-CoV-2 infection since the earliest stages of the epidemic. To date, 89442 confirmed cases have been diagnosed in Lombardy, and mortality in several municipalities has already surpassed that of the past decade. Currently, the true extent of the SARS-CoV-2 infection remains unknown as several affected subjects may have been asymptomatic or have presented mild disease, thus not resulting in the identified COVID-19 cases. MethodsThis cross-sectional study aims to define the spread of infection within the population by determining the seroprevalence of IgG antibodies directed against SARS-CoV-2 by rapid immunochromatographic testing and subsequent confirmation by serology on venous blood by liquid phase immunochemical testing, also allowing to compare the two methods. Testing will be performed on adults and minors residing, domiciled or working in several municipalities of the Lombardy Region, involved in the initial stages of the epidemic. The study will include rapid finger-prick testing and venous sampling for antibodies against SARS-CoV-2, and nasopharyngeal swabbing (NPS). Concurrent notification of test results will occur via the regional healthcare information system (SISS). DiscussionThis study was developed with the desire to understand the seroprevalence of SARS-CoV-2 infection and the epidemiological transmission characteristics of this virus. Understanding the spread and severity of the disease could help in the implementation of effective infection surveillance containment and countermeasures facilitating the identification of cases that have been exposed to the virus and the traceability of contacts. This study has been approved by the Ethics Committee of the University of Milan (35/2020).