PICOV study : "Influence of prior infection with COVID-19 on occurence of influenza-like illness or acute respiratory infection"

The study will assess the time to occurrence of influenza-like illness or acute respiratory infection in subjects previously COVID+ compared to subjects known as COVID- (controls), more specifically subjects will belong to two subgroups: nursing home residents (65+) and nursing home staff (18-65y). COVID+ is defined as a past SARS-CoV-2 infection.