Adherence to handwashing behaviour and its impact on the incidence and death of viral respiratory infectious diseases: a systematic review, meta-analysis and modelling study.

OBJECTIVES: Washing hands is considered an effective way for preventing viral respiratory infections. This study systematically investigated the global and regional adherence to hand-washing behaviour and its impact on the incidence and death of viral respiratory infectious diseases (VRIDs). METHODS: In our systematic review and meta-analysis, we searched PubMed, Embase, Web of Science and Scopus for related studies. We included observational studies with raw data of adherence to handwashing (rates of acceptability of handwashing, daily habitual handwashing and key-moment handwashing) during VRID pandemics/epidemics. Pooled rates and effect of handwashing were calculated by random-effects model and generalised linear model. RESULTS: We analysed 108 articles, generating 227 datasets. During VRID epidemics/pandemics, the global pooled rate of daily handwashing was 72.23% (95% CI 66.95% to 76.95%). The lowest rate was observed in Africa (pooled rate 59.46%, 95% CI 50.73% to 67.68%) and among public transportation workers (18.15%, 95% CI 6.54% to 41.26%). Global pooled rate of key moment handwashing was 65.11% (95% CI 59.74% to 70.28%), with the lowest rate being after handshaking (36.40%, 95% CI 18.49% to 56.52%) and among the elderly (22.86%, 95% CI 16.77% to 29.58%) and was higher during the COVID-19 pandemic than the 2009 H1N1 pandemic (72.02% vs 31.33%). The pooled rate of global acceptability of handwashing was 90.01% (95% CI 83.73% to 94.05%). Key-moment handwashing was associated with a reduction in COVID-19 incidence (β=-151.1, p=0.010), COVID-19 mortality (β=-0.066, p<0.001) and other COVID-19 related deaths (β=-0.112, p<0.001). CONCLUSION: During the VRID epidemics/pandemics, the handwashing behaviour adherence was relatively low. Health education efforts targeting public transportation workers and the elderly should be intensified. Augmented key-moment handwashing adherence potentially led to a significant reduction of the incidence and death of VRIDs. PROSPERO REGISTRATION NUMBER: CRD42024499090.