BACKGROUND: During the second COVID-19 wave, a large COVID-19 outbreak happened at a 90-bed geriatric palliative care hospital in December 2020, whereby 32% of the healthcare personnel (HCP) and 29 patients became infected within 23 days and 13 patients died. The bed occupancy rate dropped to 20%. Drastically enhanced hygiene measures directly after outbreak detection could stop further nosocomial infections among patients but were less effective among HCP. OBJECTIVE: Outbreak investigation and detection of risk factors for infection in HCP. MATERIAL AND METHODS: Anonymous online survey among HCP from January and February 2021 investigating potential risk factors for PCR positive infections (poorly fitting FFP2 masks, close contacts with positive patients, team meetings with positive HCP). RESULTS: Of 184 HCP, 96 completed the survey (52.2%), including 38 who became infected. Of the HCP 8 remained asymptomatic/oligosymptomatic, 30 HCP became ill for a median of 10 days and in 2 continuously. Factors associated with an infection were close contacts with positive patients in a time-dependent manner despite wearing an FFP2 mask (OR 6.0; 95% CI 1.6-22). Out of 88 HCP 55 described poorly fitting FFP2 masks. An infection was mostly attributed to a longer contact with positive, sometimes restless patients. The overall exhausting working situation was repeatedly mentioned. CONCLUSION: A COVID outbreak within the care-intense geriatric context is challenging to control especially among HCP. Longer patient contacts and limited compliance by patients counteracts strict hygiene measures. Vulnerability of HCP and patients requires additional preventive interventions by rapidly effective vaccinations and has to be a priority for health policy.