Washing Your Hands Reduces Spread of Respiratory Viruses Physical Interventions to Interrupt or Reduce the Spread of Respiratory Viruses: Systematic Review

Objective: To assess the effectiveness of physical interventions to reduce the spread of respiratory viruses. Design: Systematic review. Methods: The authors looked at studies of any interventions to prevent or reduce transmission of respiratory viruses and found 58 studies that met their criteria. Interventions included hand washing, hand disinfection, virucide-impregnated tissues, masks, gloves, and gowns. Study designs included retrospective and prospective cohort studies, case-control studies, cluster randomized controlled trials, and randomized controlled trials. The authors calculated odds ratios when possible. Results: Hand washing, for the most part, does work, but needs to be done frequently. Washing one’s hands >10 times daily reduced respiratory spread by 55%. Adding soap or other antiseptics increased effectiveness of hand washing in 3 of 5 studies. Alcohol-based sanitizer gels were effective in 3 randomized controlled trials, reducing respiratory spread by 20% to 50%. Among 4 studies of virucide-impregnated tissues, 2 showed a small, but statistically significant, decrease in virus transmission, while 2 other studies did not. Wearing face masks is effective. A meta-analysis of 5 case-control studies showed a decrease in disease transmission of 68% when masks were used. Two case-control studies using the N95 mask demonstrated a 90% decrease in disease transmission. However, 1 retrospective cohort study showed that wearing masks can cause facial rash and irritation. Four case control studies demonstrated a 57% decrease in transmission when gloves were used. However, gloves could also cause itching, irritation, and rash. Four case control studies also showed a 77% decrease in disease transmission when gowns were worn. When hand washing, masks, gloves, and gowns were all used simultaneously, disease spread decreased by 90%. Conclusions: Physical interventions, particularly hand washing or use of alcohol-based gels, use of face masks, gloves and gowns, can work to decrease the spread of respiratory viruses. Reviewer's Comments: Because the studies all had different designs, inclusion criteria and outcome measures, it is difficult to make definitive conclusions. The authors frankly state their disappointment in the quality of many of the studies. In addition, the quality of any meta-analysis or systematic review is limited by the quality of the individual studies being analyzed; the effectiveness of any of these measures is limited by compliance. Masks are uncomfortable, gloves are unwieldy, and frequent hand washing is often impractical or inconvenient. Patients and health-care providers need to be educated on the importance of these inexpensive strategies that can reduce the spread of respiratory illness, especially in a pandemic or epidemic situation. (Reviewer-Rachel Moon, MD).