# 2424
There are some things in public health we assume to be true pretty much on faith, because they seem reasonable, even when there isn't a lot of good science to back it up.
One of those things is the effectiveness of various types of NPI's, or Non-Pharmaceutical Interventions. Things like using facemasks and alcohol hand sanitizing gel.
We believe them to be at least somewhat protective against influenza-like illnesses, but we really don't know how protective.
Sure, we can show in a laboratory setting that alcohol gel kills germs when applied to the hands, or that facemasks can block large droplet particles, but it is a bit of a leap to assume that using these interventions will reduce your chance of catching the flu.
In a pandemic, with a vaccine unlikely to be available during the first wave for the vast majority of people, we will have to depend on NPI's such as these to protect ourselves in public, or when caring for a sick loved one.
It would be nice to know how well they actually work.
To that end the University of Michigan is looking for answers. They have been running a study called M-Flu since the 2006-2007 flu season. Here is a short video outlining the study.
The University of Michigan's MFlu page, outlining the study, is here.
Today, we are getting the preliminary results from the first year's study, and they are encouraging.
According to Allison Aiello, co-principal investigator and assistant professor of epidemiology at the U-M SPH (School of Public Health),
"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."
Aiello cautioned that the 2006-2007 flu season was a mild one, and that these early results must be interpreted cautiously.
Here is the University of Michigan's Press release.
Oct. 27, 2008
Masks, hand washing, prevent spread of flu-like symptoms by up to 50 percent
ANN ARBOR, Mich.—Wearing masks and using alcohol-based hand sanitizers may prevent the spread of flu symptoms by as much as 50 percent, a landmark new study suggests.
In a first-of-its-kind look at the efficacy of non-pharmaceutical interventions in controlling the spread of the flu virus in a community setting, researchers at the University of Michigan School of Public Health 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. Dr. Arnold Monto, professor of epidemiology, is also a principal investigator of the study.
Aiello stressed 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. Ongoing studies will test for other viruses that may be responsible for the influenza-like illness symptoms observed, she said.
"Nevertheless, these initial results are encouraging since masks and hand hygiene may be effective for preventing a range of respiratory illnesses," Aiello said.
The findings, "Mask Use Reduces Seasonal Influenza-like Illness In The Community Setting," was presented Sunday at The Interscience Conference on Antimicrobial Agents and Chemotherapy and the Infectious Diseases Society of America annual meeting in Washington, D.C.
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. Researchers followed students for incidence of influenza like illness symptoms, defined as cough with at least one other characteristic symptom such as fever, chills or body aches, Monto said.
From the third week on, 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 observed reduction in rate of flu-like symptoms remained even after adjusting for gender, race/ethnicity, hand washing practices, sleep quality, and flu vaccination.
