Protect yourself from flu by wearing a mask and washing your hands

Oct 28 2008

In what has been termed a landmark new study, it is suggested that wearing masks and washing hands prevents the spread of flu-like symptoms.

While this may seem to many to be a case of the blatantly obvious, the study is apparently a "first-of-its-kind" examination of the effectiveness of non-pharmaceutical interventions in controlling the spread of the flu virus in a community.

The researchers at the University of Michigan School of Public Health say wearing masks and using alcohol-based hand sanitizers may prevent the spread of flu symptoms by as much as 50%.

The research team carried out a study called M-Flu on more than 1,000 students from seven U-M residence halls during last year's flu season and they found that mask use and alcohol-based hand sanitizers helped reduced flu-like illness rates from 10 to 50% over the study period.

Assistant Professor of epidemiology Allison Aiello says even though the initial results are encouraging, the first year of the two-year project was a very mild flu season and only a few cases were positive for flu, so results should be interpreted cautiously.

Professor Aiello, co-principal investigator, says masks and hand hygiene may be effective for preventing a range of respiratory illnesses and ongoing studies will test for other viruses that may be responsible for the influenza-like illness symptoms seen.

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.

The researchers monitored the students for incidence of flu-like illness symptoms, defined as cough with at least one other characteristic symptom such as fever, chills or body aches.

Professor Arnold Monto also a principal investigator on the study, says from the third week on, both the mask only and mask/hand sanitizer interventions showed a significant reduction in the rate of influenza-like illness symptoms in comparison to the control group, which remained even after adjustments were made for gender, race/ethnicity, hand washing practices, sleep quality, and flu vaccination.

The researchers say in the event of a pandemic flu outbreak, non-pharmaceutical interventions such as hand washing and masks, may be critical as pharmaceutical interventions such as vaccinations and antivirals may not be available in sufficient quantity for preventing and controlling the outbreak.

Last year the Centers for Disease Control and Prevention (CDC) and the U.S. Department of Health and Human Services along with others developed an interim planning guide on the use of non-pharmaceutical interventions (NPIs) to mitigate an influenza pandemic.

The measures include voluntary home quarantine, isolation and treatment of cases, social distancing, personal protection such as face masks and hand hygiene, and school dismissal and Monto says many of these measures are difficult or impossible to evaluate in advance of a pandemic.

However, he says the use of face masks and hand hygiene interventions can be evaluated now, during seasonal influenza outbreaks, which can provide concrete evidence for decision makers.

The researchers say more research is needed to confirm whether mask use may be an effective means of reducing influenza in shared living settings as it was not possible to blind subjects and knowledge of the intervention may have influenced influenza-like symptom reporting - therefore the results of this study should be interpreted with caution.

Aiello says during year two of the study (2007-2008) a major outbreak of influenza took place, and upcoming studies will examine whether results observed during this more severe outbreak mirrored those observed during the milder year one influenza season.

The findings were presented at The Interscience Conference on Antimicrobial Agents and Chemotherapy and the Infectious Diseases Society of America annual meeting in Washington, D.C.this week.