COVID-19 risk factors amongst 14,786 care home residents: An observational longitudinal analysis including daily community positive test rates of COVID-19, hospital stays, and vaccination status in Wales (UK) between 1st September 2020 and 1st May 2021.

ObjectivesDetermine individual level risk factors for care home residents testing positive for SARS-CoV-2. Study DesignLongitudinal observational cohort study using individual-level linked data. SettingCare home residents in Wales (United Kingdom) between 1st September 2020 and 1st May 2021. Participants14,786 older care home residents (aged 65+). Our dataset consisted of 2,613,341 individual-level daily observations within 697 care homes. MethodsWe estimated odds ratios (ORs [95% confidence interval]) using multilevel logistic regression models. Our outcome of interest was a positive SARS-CoV-2 polymerase chain reaction (PCR) test. We included time dependent covariates for the estimated community positive test rate of COVID-19, hospital admissions, and vaccination status. Additional covariates were included for age, positive PCR tests prior to the study, sex, frailty (using the hospital frailty risk score), and specialist care home services. ResultsThe multivariable logistic regression model indicated an increase in age (OR 1.01 [1.00,1.01] per year of age), community positive test rate (OR 1.13 [1.12,1.13] per percent increase in positive test rate), hospital inpatients (OR 7.40 [6.54,8.36]), and residents in care homes with non-specialist dementia care (OR 1.42 [1.01,1.99]) had an increased odds of a positive test. Having a positive test prior to the observation period (OR 0.58 [0.49,0.68]) and either one or two doses of a vaccine (0.21 [0.17,0.25] and 0.05 [0.02,0.09] respectively) were associated with a decreased odds of a positive test. ConclusionsOur findings suggest care providers need to stay vigilant despite the vaccination rollout, and extra precautions should be taken when caring for the most vulnerable. Furthermore, minimising potential COVID-19 infection for care home residents admitted to hospital should be prioritised. SUMMARY BOXESO_ST_ABSSection 1: What is already known on this topicC_ST_ABSO_LICare home residents are at a high risk of COVID-19 infection, but existing literature has mainly focussed on excess mortality rather than infection risk. C_LIO_LIIn our study we were able to investigate associations between COVID-19 infections and the community positive test rate of COVID-19, the vaccination status of care home residents, hospital admissions, and frailty. C_LI Section 2: What this study addsO_LIOur study suggests an increased community positive test rate and hospital inpatients had an increased likelihood of a positive SARS-CoV-2 polymerase chain reaction test, whilst one or two doses of vaccination indicated a decreased chance of a positive test. C_LIO_LIOur findings suggest care providers need to stay vigilant despite the vaccination rollout, and extra precautions should be taken when caring for the most vulnerable, especially in a hospital setting. C_LI