A surgical mask may be as effective as more expensive respirator-type masks in protecting healthcare workers from flu and other respiratory viruses, according to new research.

A study published in JAMA compared the surgical 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 versus 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,” says Trish Perl, MD, 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.”

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 US 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,” says Perl.