Source: UT Southwestern Medical Center
Summary: The study reported 'no significant
difference in the effectiveness' of medical masks vs. N95 respirators for
prevention of influenza or other viral respiratory illness.
Researchers may finally have an answer in the
long-running controversy over whether the common surgical mask is as effective
as more expensive respirator-type masks in protecting health care workers from
flu and other respiratory viruses.
A study published today in JAMA compared the
ubiquitous surgical (or medical) mask, which costs about a dime, to a less
commonly used respirator called an N95, which costs around $1. The study
reported "no significant difference in the effectiveness" of medical
masks vs. N95 respirators for prevention of influenza or other viral
respiratory illness.
"This study showed there is no
difference in incidence of viral respiratory transmission among health care
workers wearing the two types of protection," said Dr. Trish Perl, Chief
of UT Southwestern's Division of Infectious Diseases and Geographic Medicine
and the report's senior author. "This finding is important from a public
policy standpoint because it informs about what should be recommended and what
kind of protective apparel should be kept available for outbreaks."
Medical personnel -- in particular nurses,
doctors, and others with direct patient contact -- are at risk when treating
patients with contagious diseases such as influenza (flu). A large study
conducted in a New York hospital system after the 2009 outbreak of H1N1, or
swine flu, found almost 30 percent of health care workers in emergency
departments contracted the disease themselves, Dr. Perl said.
During that pandemic, the U.S. Centers for
Disease Control and Prevention (CDC) recommended using the tighter-fitting N95
respirators, designed to fit closely over the nose and mouth and filter at
least 95 percent of airborne particles, rather than the looser-fitting surgical
masks routinely worn by health care workers, Dr. Perl said. But some facilities
had trouble replenishing N95s as supplies were used.
In addition, there are concerns health care
workers might be less vigilant about wearing the N95 respirators since many
perceive them to be less comfortable than medical masks, such as making it
harder to breathe and being warmer on the wearer's face.
Earlier clinical studies comparing the masks
and respirators yielded mixed results, said Dr. Perl, also a Professor of
Internal Medicine who holds the Jay P. Sanford Professorship in Infectious
Diseases.
The new study was performed at multiple
medical settings in seven cities around the country, including Houston, Denver,
Washington, and New York, by researchers at the University of Texas, the CDC,
Johns Hopkins University, the University of Colorado, Children's Hospital
Colorado, the University of Massachusetts, the University of Florida, and
several Department of Veterans Affairs hospitals. Researchers collected data
during four flu seasons between 2011 and 2015, examining the incidence of flu
and acute respiratory illnesses in the almost 2,400 health care workers who
completed the study.
The project was funded by the CDC, the
Veterans Health Administration, and the Biomedical Advanced Research and
Development Authority (BARDA), which is part of the U.S. Health and Human
Services Department and was founded in the years after Sept. 11, 2001, to help
secure the nation against biological and other threats.
"It was a huge and important study --
the largest ever done on this issue in North America," Dr. Perl said.
In the end, 207 laboratory-confirmed
influenza infections occurred in the N95 groups versus 193 among medical mask
wearers, according to the report. In addition, there were 2,734 cases of
influenza-like symptoms, laboratory-confirmed respiratory illnesses, and acute
or laboratory-detected respiratory infections (where the worker may not have
felt ill) in the N95 groups, compared with 3,039 such events among medical mask
wearers.
"The takeaway is that this study shows
one type of protective equipment is not superior to the other," she said.
"Facilities have several options to provide protection to their staff --
which include surgical masks -- and can feel that staff are protected from
seasonal influenza. Our study supports that in the outpatient setting there was
no difference between the tested protections."
Dr. Perl said she expects more studies to arise from the data collected in this report; she now plans to investigate the dynamics of virus transmission to better understand how respiratory viruses are spread.
.png)
.jpg)
.gif)
