COVID-19 outbreaks in nursing homes: A strong link with the coronavirus spread in the surrounding population, France, March to July 2020

BackgroundWorldwide, COVID-19 outbreaks in nursing homes have often been sudden and massive. The study investigated the role SARS-CoV-2 virus spread in nearby population plays in introducing the disease in nursing homes. Material and methodsThis was carried out through modelling the occurrences of first cases in each of 943 nursing homes of Auvergne-Rhone-Alpes French Region over the first epidemic wave (March-July, 2020). The cumulative probabilities of COVID-19 outbreak in the nursing homes and those of hospitalization for the disease in the population were modelled in each of the twelve Departements of the Region over period March-July 2020. This allowed estimating the duration of the active outbreak period, the dates and heights of the peaks of outbreak probabilities in nursing homes, and the dates and heights of the peaks of hospitalization probabilities in the population. Spearman coefficient estimated the correlation between the two peak series. ResultsThe cumulative proportion of nursing homes with COVID-19 outbreaks was 52% (490/943; range: 22-70% acc. Departement). The active outbreak period in the nursing homes lasted 11 to 21 days (acc. Departement) and ended before lockdown end. Spearman correlation between outbreak probability peaks in nursing homes and hospitalization probability peaks in the population (surrogate of the incidence peaks) was estimated at 0.71 (95% CI: [0.66; 0.78]). ConclusionThe modelling highlighted a strong correlation between the outbreak in nursing homes and the external pressure of the disease. It indicated that avoiding disease outbreaks in nursing homes requires a tight control of virus spread in the surrounding populations.

Automated summary

This study investigated the role of SARS-CoV-2 virus spread in nearby population in introducing COVID-19 outbreaks in nursing homes. The results showed a strong correlation between the outbreak in nursing homes and the external pressure of the disease, highlighting the importance of controlling virus spread in surrounding populations to prevent outbreaks in nursing homes.