Estimating spatially disaggregated probability of severe COVID-19 and the impactof handwashing interventions : The case of Zimbabwe

The severity of COVID-19 disease varies substantially between individuals, with someinfections being asymptomatic while others are fatal. Several risk factors have been identified that affect theprogression of SARS-CoV-2 to severe COVID-19. They include age, smoking and presence of underlying comorbidities suchas respiratory illness, HIV, anemia and obesity. Given that respiratory illness is one such comorbidity and is affectedby hand hygiene, it is plausible that improving access to handwashing could lower the risk of severe COVID-19 among apopulation. In this paper, the authors estimate the potential impact of improved access to handwashing on therisk of respiratory illness and its knock-on impact on the risk of developing severe COVID-19 disease across Zimbabwe.They use a geospatial model that allows us to estimate differential clinical risk at the district level. Resultsshow that the current risk of severe disease is heterogeneous across the country, due to differences inindividual characteristics and household conditions. This study demonstrates how household level improved access tohandwashing could lead to reductions in the risk of severeCOVID-19 of up to 16% from the estimated current levels across all districts. Taken alongside the likely impact ontransmission of SARS-CoV-2 itself, as well as countless other pathogens, this result adds further support for theexpansion of access to handwashing across the country. It also highlights the spatial differences in risk of severeCOVID-19, and thus the opportunity for better planning to focus limited resources in high risk areas in order topotentially reduce the number of severe cases.