Lessons learnt from a nosocomial COVID-19 outbreak in a geriatric acute care ward with a high attack rate.

Nosocomial COVID-19 in older patients has a high mortality rate. We describe an outbreak of COVID-19 in a geriatric acute care unit (GACU) in March/April 2020 and the lessons learnt regarding prevention. Thirty-six patients were diagnosed with COVID-19 during that 2-month period, in France's "first wave" of SARS-CoV-2 infections. Thirty (83.3%) were considered nosocomial. Attributable mortality reached 33.3% in these patients. Healthcare workers (HCW) were not spared, with an overall attack rate of 36.8%, but the rate was especially high among nurse assistants (68.2%). Repeated testing, single rooms, hand hygiene, and good use of personal protective equipment are paramount in GACUs to prevent in-hospital COVID-19 outbreaks.