study inclusion criteria; - written informed consent - healthcare workers at nursing homes with resident contact - willingness to adhere to study protocol additional inclusion criteria for primary objective 2 (reinfection after vaccination) - sars-cov-2 vaccination list the study

study inclusion criteria; - written informed consent - healthcare workers at nursing homes with resident contact - willingness to adhere to study protocol additional inclusion criteria for primary objective 2 (reinfection after vaccination) - sars-cov-2 vaccination list the study