BACKGROUND: The population of adult residential care homes has been shown to have high morbidity and mortality in relation to COVID-19 .
METHODS: We examined 3115 hospital discharges to a national cohort of 1068 adult care homes and subsequent outbreaks of COVID-19 occurring between 22 February and 27 June 2020 . A Cox proportional hazards regression model was used to assess the impact of time-dependent exposure to hospital discharge on incidence of the first known outbreak, over a window of 7-21 days after discharge, and adjusted for care home characteristics, including size and type of provision .
RESULTS: A total of 330 homes experienced an outbreak, and 544 homes received a discharge over the study period . Exposure to hospital discharge was not associated with a significant increase in the risk of a new outbreak (hazard ratio 1.15 , 95% CI 0.89 , 1.47, P = .29) after adjusting for care home characteristics . Care home size was the most significant predictor . Hazard ratios (95% CI) in comparison with homes of <10 residents were as follows : 3.40 (1.99 , 5.80) for 10-24 residents; 8.25 (4.93 , 13.81) for 25-49 residents; and 17.35 (9.65 , 31.19) for 50+ residents . When stratified for care home size, the outbreak rates were similar for periods when homes were exposed to a hospital discharge, in comparison with periods when homes were unexposed .
CONCLUSION: Our analyses showed that large homes were at considerably greater risk of outbreaks throughout the epidemic, and after adjusting for care home size, a discharge from hospital was not associated with a significant increase in risk.