Investigating the Efficacy of Various Handwashing Methods against Enveloped and Non-Enveloped Viruses

Respiratory and diarrheal diseases are leading causes of death worldwide. Handwashing may reduce disease; however, recommended methods (soap and water for 20 seconds) are not always possible, particularly in low-resource settings. The aim of this study is to evaluate handwashing when recommended methods are not feasible, including washing with water only, washing with soapy water, washing for a short duration, using alcohol-based hand sanitizer (ABHS), and cleaning hands with towels. To evaluate laboratory efficacy, we seeded MS2 (a non-enveloped virus) and Phi6 (an enveloped virus) onto the hands of volunteers who then washed their hands. Viruses remaining were recovered and quantified using culture-based and molecular methods to determine the log reduction value (LRV) after washing. Results indicated that washing with water only and with soapy water were similar to washing with soap and water for 20 seconds for both viruses (median LRV for MS2 = 2.8; Phi6 = 3.2). Most towel alternative conditions had LRVs significantly smaller than LRVs from washing with soap and water for either virus. LRVs of ABHS and soap and water for 5 seconds were similar to soap and water for 20 seconds for Phi6 but less for MS2 (median MS2 LRV differences = 2.5 and 0.51 for ABHS and soap and water for 5 seconds, respectively). Additionally, LRVs determined using molecular methods were in agreement with those obtained using culture-based methods. These results suggest some handwashing alternatives were as effective as recommended methods whereas others were not, and inform recommendations and future research on handwashing alternatives in low-resource settings.