Intensive action has been taken around the globe to fight the corona virus SARS-COV-2 (COVID-19) pandemia. Clinical symptoms of the infection appear to be variable, from basically asymptomatic infections and mild, flu-like symptoms up to severe respiratory insufficiency, requiring mechanical ventilation at the intensive care unit, and death. Broad testing for COVID-19 infection has been proven difficult in clinical practice and hampered by limited resources. Urgently needed epidemiological data on the rate of silent, asymptomatic infections in the population and the percentage of individuals that have already developed immunity are still missing. Within this study we therefore plan to (i) determine the proportion of asymptomatic COVID-19 virus carriers in (a) German Cancer Research Center (DKFZ) employees, who work and are present at the center during the time of extended minimum operation and (b) in all DKFZ employees before onboarding when extended minimum operation has been terminated. We plan to (ii) develop a high-throughput assay for COVID-19 testing as well as (iii) a serum-based COVID-19 antibody assay. Finally, we will (iv) analyze for a possible correlation between oral microbiome and COVID-19 infection status.