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.
The investigators aim to determine the immune status of the employees of the cantonal police of Bern against SARS-CoV-2 over a period of 1 year, and to investigate the risk profile of the study participants and their risk of SARS-CoV-2 exposure in their working and private environments, as well as to evaluate the use of personal protective equipment at potential exposure instances.