Hand washing, face masks may significantly reduce spread of influenza-like illness

Issue: November 2008

Taking precautionary measures such as wearing face masks and using alcohol-based hand sanitizer may be an effective deterrent to stop the spread of influenza-like illness. Such measures were associated with a significant reduction in the spread of influenza symptoms, according to the results of a study by researchers at the University of Michigan School of Public Health.

The study, presented by Allison Aiello, MD, professor of epidemiology at the University of Michigan School of Public Health, examined the efficacy of non-pharmaceutical interventions in controlling the spread of influenza-like illness in a community setting.

More than 1,400 students who lived in residence halls at the University of Michigan participated in the study. Participating students were assigned to one of three groups at the beginning of influenza season. The first group wore a standard medical procedure face mask alone; the second group used hand sanitizer and a mask; the third group served as a control group and used neither. The study duration was six weeks.

Students were followed for any incidence of influenza-like illness, defined as cough with at least one other characteristic symptom such as fever, chills or body aches.

By week four, participants in the mask group had a 29% lower rate of influenza-like illness than the control group. Participants in the mask/hand hygiene group had a 26% lower rate of influenza- like illness. By week six, these figures had increased to 45% and 41% respectively.

The reduction in symptoms remained even after adjusting for gender, race/ethnicity, hand washing practices, sleep quality and influenza vaccination, according to the researchers.

Aiello said these findings were noteworthy, particularly because the study was conducted during a mild influenza season.

Presented at: ICAAC/IDSA joint meeting. Oct. 25-28, 2008. Washington, DC.