Residents in nursing homes for the senior citizens (NH) are at high risk for death from COVID-19. We investigated whether repeated non-mandatory RT-PCR SARS-CoV-2 surveillance of NH staff and visitors reduces COVID-19 incidence rates in NH residents and allows to reduce visiting restrictions.

Nursing homes for senior citizens are considered risk areas for the transmission of SARS-CoV-2. To protect these risk groups, different strategies have been implemented within the framework of legally applicable conditions. The aim of this study is to observe two procedural standards (e.g. visiting restrictions, hygiene measurements):

• On the one hand, a standard procedure without testing of visitors and employees and
• on the other hand, a standard procedure with additional surveillance by voluntary testing of visitors and staff for SARS-CoV-2 and associated relaxation of measures for contact of visitors with residents.

Both standard procedures are designed to ensure adequate protection against infection. The standard procedure with the use of relaxing the measures after testing aims to make the experience of social isolation more bearable for the residents of care facilities and thus less stressful from a psychological point of view. The extent of such possible effects is not the subject of the present study.

The primary aim of the study is to observe the number of SARS-CoV-2 infections among residents of nursing homes for senior citizens under different procedural standards for infection control.

In this study, various measures specified by care institutions for visits to senior citizens' homes are accompanied by scientific screening. The aim of the screening and the analysis of infection protection measures is to enable this vulnerable group to regain participation in society but still slow down the spread of the virus and prevent an outbreak.

The (mobile) infection control center ("Coronamobil") of the University Hospital of Cologne (UKK) makes a decisive contribution to the longitudinal investigation of a risk population and to the early detection of chains of infection in addition to the surveillance carried out by the authorities. In this study, the Coronamobil and personnel are provided to avoid an additional screening burden for the homes.

Surveillance of nursing homes allows protection of particularly vulnerable populations in the SARS-CoV-2 pandemic, and additional controlled contact. An evidence-based, safe and human visit concept could be transferred from Cologne to the whole of Germany. The resulting scientific knowledge would additionally provide a foundation for the control of future outbreak situations.

Inclusion Criteria:

• One-time or frequent visitors in care facilities of the INH group who want to be tested for SARS-CoV-2 voluntarily
• employees (HCW) in care facilities of the INH group who want to be tested voluntarily
• Successful declaration of consent via the UKK Corona web tool

Exclusion Criteria:

• Visitors and employees in care facilities of the INH group with signs of SARS-CoV-2 infection
• No participants in the context of the study are in principle:
• one-time and frequent visitors in care facilities of the CNH group
• employees in care facilities of the CNH group
• Residents in care facilities of the CNH and the INH group

• One-time or frequent visitors in care facilities with standard 2 who want to be tested voluntarily
• employees in care facilities with standard 2 who want to be tested voluntarily
• Successful declaration of consent via the UHC Corona Web Tool

IPD can be made available upon request