Immune Response of Asymptomatic EHPAD Employees Infected With COVID-19

The investigators performed in April 2020, a screening campaign of asymptomatic staff working in elderly nursing homes in Paris France (EHPAD), where the virus had been circulating actively in March and April 2020. Among 241 employees tested in four nursing homes, 32 (13.2%) were asymptomatic carriers of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-Cov-2). Few data are available concerning the humoral immune response of asymptomatic carriers, the elicitation and duration of neutralizing antibodies and the duration of protection. The purpose of the study is to determine whether these asymptomatic persons develop a humoral immune response, whether this immune response is durable and whether it is protective against the risk of reinfection