The study by researchers at the University of Michigan School of Public Health, is the first-of-its-kind to deal with the efficacy of non-pharmaceutical interventions in controlling the spread of the flu virus in communities
In the study, the researchers studied more than 1,000 student subjects from seven U-M residence halls during last year's flu season.
"The first-year results (2006-2007) indicate that mask use and alcohol-based hand sanitizer help reduce influenza- like illness rates, ranging from 10 to 50 percent over the study period," said Allison Aiello, co-principal investigator and assistant professor of epidemiology at the U-M SPH.
Aiello pointed out that the first year of the two-year project, called M-Flu, was a very mild flu season and only a few cases were positive for flu, so results should be interpreted cautiously.
"Nevertheless, these initial results are encouraging since masks and hand hygiene may be effective for preventing a range of respiratory illnesses," she said.
At the start of flu season in the last two years, participants were randomly assigned to six weeks of wearing a standard medical procedure mask alone, mask use and hand sanitizer use, or a control group with no intervention.
For the study, the researchers followed students for incidence of influenza like illness symptoms, which according to the one of the principal investigator of the study, Dr. Arnold Monto, can be defined as cough with at least one other characteristic symptom such as fever, chills or body aches.
Starting from the third week, both the mask only and mask/hand sanitizer interventions showed a significant or nearly significant reduction in the rate of influenza-like illness symptoms in comparison to the control group.
The reduction persisted in rate of flu-like symptoms even after adjusting for gender, race/ethnicity, hand washing practices, sleep quality, and flu vaccination.
Non-pharmaceutical interventions such as hand washing and masks, especially in a pandemic flu outbreak, are critical to study because pharmaceutical interventions such as vaccinations and antivirals may not be available in sufficient quantity for preventing and controlling pandemic influenza outbreaks.
"Although a few of these measures can be evaluated during seasonal influenza outbreaks, many are difficult or impossible to evaluate in advance of a pandemic. However, use of face masks and hand hygiene interventions can be evaluated now, during seasonal influenza outbreaks, which can provide concrete evidence for decision makers," said Monto.
The findings, "Mask Use Reduces Seasonal Influenza-like Illness In The Community Setting," was presented at The Interscience Conference on Antimicrobial Agents and Chemotherapy and the Infectious Diseases Society of America annual meeting in Washington, D.C.