Infection Control & Hospital Epidemiology (2019), 40, 232–234 doi:10.1017/ice.2018.326
Concise Communication
How well do N95 respirators protect healthcare providers against aerosolized influenza virus?
Werner E. Bischoff MD, PhD, FSHEA1, JoLyn Turner PhD1, Gregory Russell MS2, Maria Blevins1, Engy Missaiel MD3 and John Stehle Jr PhD, CIC4 1Internal Medicine, Section on Infectious Diseases, and Infection Prevention and Health System Epidemiology, Wake Forest Baptist Medical Center,
Winston-Salem, North Carolina, 2Department of Biostatistical Sciences, Wake Forest School of Medicine, Winston Salem, North Carolina, 3Department of General Surgery, Wake Forest School of Medicine, Winston Salem, North Carolina and 4Infection Prevention and Health System Epidemiology, Wake Forest Baptist Medical Center, Winston-Salem, North Carolina
Abstract
N95 respirator masks are recommended for protection against respiratory viruses. Despite passing fit-testing 10% of N95 respirator users encountered breakthroughs with exposure to influenza virus compared to full protection provided by a powered air purifying respirator. The current recommendation of N95 respirators should be evaluated for endemic and emerging scenarios.
(Received 11 October 2018; accepted 19 November 2018)
Relatively little is known about how best to protect ourselves and others against viral respiratory pathogens. This gap in knowledge is a major concern in light of endemic and emerging Influenza viruses. TheWorld Health Organization and the Centers of Disease Control and Prevention (CDC) recommend the use of N95 respirators during exposure to novel influenza viruses or during aerosol generating procedures involving seasonal influenza.1,2 However, how well N95 respirators actually protect healthcare providers remains unknown.3 We assessed the efficacy of a commercially available N95 respirator mask against a novel half-mask powered air purifying respirator (PAPR) in a human exposure model.
Methods
Healthy employees and students at Wake Forest School of Medicine (WFSM) were randomized to an N95 (Kimberly-Clark N95 particulate filter respirator, Irving, TX) or aPAPR (Pioneer 300, Celios, Tampa, FL) exposure group. None of the participants had received the seasonal, live attenuated influenza vaccine strains (LAIV; 2015/16 FluMist Quadrivalent, Gaithersburg, MD; 2×106.5–7.5 fluorescent focus-forming units) before enrollment. Informed consent was obtained from all participants. The study was approved by theWFSM Institutional Review Board. Participants completed qualitative fit-testing (Qualitative Fit
Test Apparatus FT-10, 3M, St Paul, MN). Nasal swabs (FLOQS- wabs, Copan Flock Technologies, Brescia, Italy) were obtained to
Author for correspondence: Werner E. Bischoff MD, Internal Medicine/Infectious
Diseases, Medical Center Boulevard, Winston-Salem, NC 27157. E-mail: wbischof@
wakehealth.edu PREVIOUS PRESENTATION: These findings were presented in part as a poster (no. 441) at IDWeek 2017 on October 5, 2017, in San Diego, California.
Cite this article: Bischoff WE, et al. (2019). How well do N95 respirators protect
healthcare providers against aerosolized influenza virus? Infection Control & Hospital Epidemiology 2019, 40, 232–234. doi: 10.1017/ice.2018.326
© 2018 by The Society for Healthcare Epidemiology of America. All rights reserved.
establish absence of influenza virus before exposure. Study subjects were asked to dress in disposable attire and to don and fit-check the respective devices and airtight goggles. After placement of the individual in a test chamber and a 2-minute evacuation run of a HEPA air filtration unit, subjects were exposed to aerosolized LAIV (MQ5800 Airial, Medquip, Bluffon, SC) for 20 minutes (Fig. 1). During exposure, participants performed a standardized set of movement and reading exercises to mimic normal activity. Nasal swabs were collected following a test chamber evacuation run. Virus RNA extraction was carried out using the QIAamp Viral
RNAMini Extraction Kit (catalog no. 52906, Qiagen, Valencia, CA). For quantitative reverse transcription polymerase chain reaction (qRT-PCR) detection of the influenza A strains, the M gene of the master donor virus strain A/Switzerland/9715293/2013 (H3N2)–like virus MP segment was the amplification target, using the following primer set (IDT, Integrated DNA Technologies, Skokie, IL):
∙ FluAforwardprimer(FLUAM-1F):5′-AAGACCAATCCTGT CACCTCTGA-3′ (IDT ref. no. 137171480)
∙ Flu A reverse primer (FLUAM-1R): 5′-CAAAGCGTCTA CGCTGCAGTCC-3′ (IDT ref. no. 137171481)
A DNA vector containing the M gene region for influenza A
was synthesized by GeneArt (Burlingame, CA) in a pMA(ampR) vector. The influenza A standard curve (DNA vector) was used to quantify the amount of viral RNA present in the samples produced from the aerosolized runs (standard curve, 0.1–100,000 copies/µL). Quantitative real-time PCR was performed using the QuantiTect SYBR Green RT-PCR Kit (catalog no. 204245, Qiagen). Plates were assayed in the ABI Prism Fast RT-PCR system (ABI, Thermo Fisher Scientific, Waltham, MA) using thermocycler conditions described previously.4 Participants were randomized using block randomization of varying block sizes. Summary statistics, including means, ranges,
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