Impact of visitation and cohorting policies to shield residents from covid-19 spread in care homes: an agent-based model.

• Shielding residents in care homes is not as effective as previously predicted in a number of studies. • Maintaining a low risk of transmission per contact helps reduce the effect of relaxing visitation. • Cohorting of residents and staff reduces the spread of COVID-19. • The risk of outbreak occurrence in a care home is associated with its population size. This study examines the impact of visitation and cohorting policies as well as the care home population size upon the spread of COVID-19 and the risk of outbreak occurrence in this setting. Agent-based modelling The likelihood of the presence of an outbreak in a care home is associated with the care home population size. Cohorting of residents and staff into smaller, self-contained units reduces the spread of COVID-19. Restricting the number of visitors to the care home to shield its residents does not significantly impact the cumulative number of infected residents and risk of outbreak occurrence in most scenarios. Only when the community prevalence where staff live is considerably lower than the prevalence where visitors live (the former prevalence is less than or equal to 30% of the latter), relaxing visitation increases predicted infections much more significantly than it does in other scenarios. Maintaining a low infection probability per resident-visitor contact helps reduce the effect of allowing more visitors into care homes. Our model predictions suggest that cohorting is effective in controlling the spread of COVID-19 in care homes. However, according to predictions shielding residents in care homes is not as effective as predicted in a number of studies that have modelled shielding of vulnerable population in the wider communities. [ABSTRACT FROM AUTHOR]