Asymptomatic SARS COV-2 carriers among nursing home staff: A source of contamination for residents?

OBJECTIVES: To show that circulation of SARS-COV-2 in nursing homes in France can come from staff as well as residents’ families, whether they are known or not to have had COVID-19. METHODS: This study reports a screening campaign of asymptomatic staff working in elderly nursing homes in Paris where the virus had been circulating actively in March and April 2020. RESULTS: Before the screening campaign, the rate of symptomatic COVID-19 was 23.3% among the residents and 12.1% among their home employees. Within a 72 h screening period, all employees not known to have the virus were screened by RT-PCR in nasopharyngeal swabs. Among the 241 screened employees, 32 (13.3%) tested positive for SARS-CoV-2 on RT-PCR. SARS-CoV-2 carriers and non-carriers did not differ in term of gender, age or type of staff. Staff carrying SARS-CoV-2 were strictly asymptomatic in 75% of cases while during the days following or before the test, 25% presented mild symptoms of COVID-19. Considering both symptomatic and asymptomatic cases, 66 out of 281 (23.5%) of the home employees had been carriers for COVID-19. CONCLUSION: Screening for viral carriage of asymptomatic staff in nursing homes can avoid contact and transmission to frequently severely vulnerable residents.