i) To determine the extent of infection with seroprevalence data in the special population of police officers of the canton Bern.
ii) To determine risk factors for infection by comparing the proportion of seropositivity (infected versus noninfected individuals). The investigators hypothesize that police officers with fieldwork activity will have a higher seroprevalence than will office and administration personnel. The investigators hypothesize that working in the city of Bern will be associated with a higher seroprevalence than will working in other geographic areas of the canton (i.e. rural area).
iii) To monitor COVID-19 antibody titres and neutralizing capacity over time and to associate them with reinfection rates and infection-free intervals in police officers after accidental contact with a proven COVID-19 case. The investigators hypothesize that in seropositive individuals, there will be a decreasing dynamic of antibody titres over the one-year study period, and hence, a decrease of neutralizing capacity.
