Respirator Masks Best for Swine Flu Health Workers
THURSDAY Sept. 3, 2009 -- Because people can catch the new H1N1 swine flu by inhaling the virus, health-care workers who deal with flu patients should wear properly fitted N95 disposable respirator masks, a new report from the Institute of Medicine advises.
These masks are not the same as loosely fitted surgical masks. N95 respirators fit tightly around the mouth and nose and have filters that can block about 95 percent of the flu virus, according to the report released Thursday.
"The U.S. Centers for Disease Control and Prevention guidelines for protection of health-care workers during an H1N1 outbreak have been that those in close contact with people who have H1N1 flu should wear N95 respirators," said Dr. Kenneth I. Shine, chair of the Committee on Respiratory Protection for Healthcare Workers in the Workplace Against Novel H1N1 Influenza A.
The Institute evaluated the effectiveness of N95 respirators and medical masks in protecting wearers from the H1N1 flu at the request of the CDC and other government agencies.
"We saw a fair amount of evidence that suggests that this virus can be transmitted through the air," said Shine, who is also executive vice chancellor for health affairs at the University of Texas. "How much of transmission is due to that is still an unproven issue and needs a lot of research."
Shine noted that the virus is also transmitted by person-to-person contact and by contact with surfaces that have been exposed to the virus. Hence, the advice to wash hands often.
Tests showed that the protection provided by N95 masks was eight to 12 times greater than that offered by surgical masks, the report said.
In addition, tests of surgical masks show wide variations in protection. They can filter from 4 percent to as much as 90 percent of the virus, but there is no way of controlling leakage around the edges of the mask, Shine said.
"Surgical masks were not designed to protect people from airborne infection, and they are not likely to be effective, whereas N95 respirators have a much better ability to protect health-care workers," he said.
Based on these findings, the report recommends that health-care workers should use N95 respirators. Because a tight seal is so important, they should be individually fit-tested, it said.
The N95 respirators are not a perfect solution, however. "We are aware that there are shortages of these respirators," Shine said. Also, some health-care workers, particularly anyone with heart or lung disease or other health conditions, could find it difficult to breathe through a respirator mask. Those people "should talk with your doctor before using a respirator," the CDC says.
The N95 face masks cost $10 to $20 a box depending on the manufacturer and the model. Like surgical masks, they should "be worn only once and then thrown away," the agency says.
While not advising surgical masks for health-care workers, Shine said he would like to see flu patients wear them. "There, the principal affect is to decrease droplet spread from sneezing and coughing," he said.
Another expert said the general public shouldn't rush to buy either type of mask to protect them from the H1N1 flu.
"Surgical masks are not effective and will only spread panic," said Dr. Marc Siegel, an associate professor of medicine at New York University Langone Medical Center in New York City. "Only people with flu should use them."
"Health-care workers in direct contact with flu patients should use N95 respirator masks," Siegel added. "They are the most effective, but are not for general use."
Because it is still unclear what proportion of influenza cases gets spread by airborne particles, the report called for more research on flu transmission. More cooperation among three government agencies -- the U.S. Food and Drug Administration, the U.S. Occupational Safety and Health Administration and the CDC's National Institute for Occupational Safety and Health -- in evaluating and recommending protective masks is also warranted, Shine said.
Dr. Pascal James Imperato, dean and distinguished service professor of the School of Public Health at the State University of New York Downstate Medical Center in Brooklyn, agreed with the recommendations "based on current scientific knowledge."
The call for more research on the routes of flu transmission, in particular, will benefit the general public, he said.
As scientists learn more about how flu spreads, these experts said, they'll be better able to recommend protective guidelines.
For more information on H1N1 swine flu, visit the Flu.Gov.
Posted: September 2009
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