Mass testing for discovery and control of COVID-19 outbreaks in adult social care: an observational study and cost-effectiveness analysis of 14 805 care homes in England.

Abstract

Introduction: We retrospectively evaluated the impact of COVID-19 testing among residents and staff in social care homes in England.

Methods: We obtained 80 million reported PCR and lateral flow device (LFD) test results, from 14 805 care homes (residents and staff) in England, conducted between October 2020 and March 2022. These testing data were then linked to care home characteristics, test costs and 24 500 COVID-19-related deaths of residents. We decomposed the mechanism of outbreak mitigation into outbreak discovery and outbreak control and used Poisson regressions to investigate how reported testing intensity was associated with the size of outbreak discovered and to uncover its association with outbreak control. We used negative binomial regressions to determine the factors influencing COVID-19-related deaths subsequent to outbreaks. We performed a cost-effectiveness analysis of the impact of testing on preventing COVID-19-related deaths of residents.

Results: Reported testing intensity generally reflected changes in testing policy over time, although there was considerable heterogeneity among care homes. Client type was the strongest determinant of whether COVID-19-related deaths in residents occurred subsequent to testing positive. Higher staff-to-resident ratios were associated with larger outbreak sizes but rapid outbreak control and a decreased risk of COVID-19-related deaths. Assuming our regression estimates represent causal effects, care home testing in England was cost-effective at preventing COVID-19-related deaths among residents during the pandemic and approximately 3.5 times more cost-effective prior to the vaccine rollout.

Conclusions: PCR and LFD testing was likely an impactful intervention for detecting and controlling COVID-19 outbreaks in care homes in England and cost-effective for preventing COVID-19-related deaths among residents. In future pandemics, testing must be prioritised for care homes, especially if severe illness and death particularly affect older people or individuals with characteristics similar to care home residents, and an efficacious vaccine is unavailable.