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N95 respirators, medical masks offer similar protection from flu
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A comparison of N95 respirators and medical masks for the prevention of influenza demonstrated no significant difference in the incidence of laboratory-confirmed influenza among health care workers in outpatient settings, according to findings from The Respiratory Protection Effectiveness Clinical Trial (ResPECT).
Although many facilities use N95 respirators and medical masks to protect health care workers from influenza and other respiratory illness, studies comparing their effectiveness have been “inconclusive,” researchers wrote.
Lewis J. Radonovich, Jr., MD, chief of research for the CDC’s National Personal Protective Technology Laboratory, and colleagues conducted a cluster randomized pragmatic effectiveness study at 137 outpatient study sites at seven United States medical centers. Each year, pairs of outpatient sites — known as clusters — within each center were matched and randomly assigned to the N95 respirator or medical mask group during the 12-week period of peak viral respiratory illness, with the final follow-up occurring in June 2016.
According to the findings, 1,993 participants from 189 clusters were assigned to wear N95 respirators and 2,058 participants from 191 clusters were assigned to wear medical masks.
In the N95 group, the researchers observed 207 laboratory-confirmed influenza infection events, and in the medical mask group, they observed 193 events.
Additionally, there were 1,556 acute respiratory illnesses in the N95 group compared with 1,711 in the medical mask group (difference, –21.9 per 1,000 health care personnel [HCP] seasons; 95% CI, 48.2 to 4.4). Radonovich and colleagues recorded 679 laboratory-detected respiratory infections in the N95 group compared with 745 in the mask group (difference, –8.9 per 1,000 HCP seasons; 95% CI, 33.3 to 15.4), 371 laboratory-confirmed respiratory illness events in the N95 group compared with 417 in the mask group (difference, –8.6 per 1,000 HCP seasons; 95% CI, 28.2 to 10.9) and 128 influenza-like illness events in the N95 group compared with 166 in the mask group (difference,–11.3 per 1,000 HCP seasons; 95% CI, 23.8 to 1.3).
According to the findings, 90.2% of participants in the medical mask group said they “always” or “sometimes” wore their assigned devices compared with 89.4% in the N95 group.
In a related editorial, Hilary M. Babcock, MD, MPH, president of the Society for Healthcare Epidemiology of America and professor of medicine at Washington University School of Medicine, and Thomas R. Talbot, MD, MPH, an assistant professor of medicine at Vanderbilt University Medical Center, wrote that the study by Radonovich and colleagues “in many ways [was] specifically designed to address limitations of earlier studies.”
“The ResPECT trial findings offers scientific support and insight about appropriate protection for health care personnel against respiratory viral infections in the outpatient setting,” Babcock told Infectious Disease News. “More importantly, this study provides needed guidance to program and policy makers that, under usual use conditions, medical masks and respirators offer almost the same protection against respiratory viruses during outpatient care.” – by Marley Ghizzone
Disclosures: Babcock and Talbot report no relevant financial disclosures. Radonovich reports no relevant financial disclosures. Please see the study for all other authors’ relevant financial disclosures.
Perspective
Back to TopMask wearing is a key component of personal protective equipment (PPE) while caring for patients with influenza and other viral respiratory pathogens. Medical masks (also called “facemasks” and “surgical masks”) have historically been recommended for this purpose, but N95 respirators were recommended by the CDC to be worn by health care personnel (HCP) during the 2009 pandemic. That recommendation was criticized for being not entirely evidence based and was followed by shortages of N95 respirators nationally. Subsequent studies comparing medical masks with N95 respirators showed conflicting results. Radonovich and colleagues conducted the first large multicenter randomized trial to determine whether N95 respirators are superior to medical masks for preventing HCP acquisition of influenza. This study included outpatient sites over four peak respiratory viral illness seasons and showed no significant differences in the incidence of laboratory-confirmed influenza, acute respiratory illness, laboratory-detected or confirmed respiratory infections and influenza-like illnesses. The major advantages of this study were the large size, inclusion of a variety of real-world clinical settings, cluster randomization within sites each study year, observation over multiple seasons, lab confirmation of symptomatic infection as well as surveillance testing to detect evidence of asymptomatic infection during each season and tracking of compliance with mask wearing among the participants. The major finding that N95 respirators appear no better than medical masks in preventing influenza acquisition is important because it provides much needed clarity around the choice of PPE for viral respiratory illness prevention, the creation of infection prevention policies, supply chain planning and pandemic preparedness. As with any study, caution should be taken when applying results to other settings, and it is unknown if the findings would extrapolate to the inpatient arena. However, inclusion of emergency departments likely mitigates this somewhat because these patients are largely similar to inpatients in terms of severity of illness and contagiousness.
References:
CDC. Interim recommendations for facemask and respirator use to reduce 2009 influenza A (H1N1) virus transmission. https://www.cdc.gov/h1n1flu/masks.htm Accessed September 5th, 2019.
Gralton J, McLaws ML. Crit Care Med. 2010;doi:10.1097/CCM.0b013e3181b9e8b3.
Loeb M, et al. JAMA. 2009;doi:10.1001/jama.2009.1466.
MacIntyre CR, et al. Am J Respir Crit Care Med. 2013;doi:10.1164/rccm.201207-1164OC.
MacIntyre CR, et al. Influenza Other Respir Viruses 2011;doi:10.1111/j.1750-2659.2011.00198.x.
Patel A, et al. Health Security. 2017;doi:10.1089/hs.2016.0129.
Radonovich Jr. LJ, et al. JAMA. 2019;doi:10.1001/jama.2019.11645.
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