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Respiratory Protection in the Outpatient Setting: The ResPECT Trial

Amesh A. Adalja, MD, FACP, FACEP, FIDSA | September 9, 2019

In many ways, influenza is one of the most important infectious diseases, and, arguably, the most important aspect of influenza is its ability to cause pandemics; thus, it requires special preparedness activities. As a respiratory virus, influenza is spread through respiratory droplets that travel no more than 3 to 6 feet before falling to the ground due to the force of gravity. However, it has also been generally established that some proportion of influenza spread is via the airborne route because tiny particles of the virus remain suspended in the air.

This type of spread may disproportionately occur with aerosol-generating procedures such as bronchoscopy, but it also may occur, to some degree, under ordinary circumstances. Because of the possibility of airborne transmission, N95 masks are sometimes recommended for healthcare workers in certain settings, whereas medical masks are the usual standard of care. A new multicenter study, led by the Pittsburgh-based CDC National Personal Protective Technology Lab, attempts to answer the question of whether N95 masks offer greater protection than medical masks to healthcare workers in an outpatient setting.

Cluster-Randomized Trial Shows No Benefit with N95 Masks

The ResPECT trial was a cluster randomized multicenter trial that took place between 2011 and 2015 and involved outpatient centers such as dialysis units, outpatient clinics, emergency departments, and dental clinics. Each of the 189 clusters was randomized to N95 masks or medical masks during a 12-week peak of respiratory virus transmission when healthcare workers were within 6 feet of a patient with suspected or confirmed respiratory infection. There were approximately 2,000 research participants. The primary outcome of the study was evidence of laboratory-confirmed influenza.

The study found that laboratory-confirmed influenza was no more common in the group with ordinary medical masks than in the N95 group: 207 cases of influenza infection occurred in the N95 respirator group, and 193 occurred in the group wearing medical masks.

Secondary outcomes such as respiratory illness also were no different between the groups. Adherence was reported to be no different between the groups as well.

Prioritizing Infection Control in Outpatient Settings

This is an important trial that goes a long way toward answering a clinically and operationally relevant question. Donning N95 masks is cumbersome, wearing them is not comfortable, and procuring them is relatively more expensive than buying ordinary masks. During future influenza pandemics, there may be calls for the use of N95 masks in all settings – as was the case during the early days of the 2009 H1N1 pandemic – but the ResPECT trial demonstrates that, in outpatient settings, this did not decrease the force of infection.

Outpatient settings such as urgent care centers and emergency departments are extremely harried environments. They are not known as bastions of infection control and personal protective equipment (PPE) use, and even the presence of many epidemiologically significant organisms does not prompt healthcare workers to wear the appropriate PPE. Having data such as that provided by ResPECT helps prioritize infection control procedures in this setting. It would be interesting to know, given that outpatient settings (unlike inpatient settings) do not have stringent infection control protocols and policies, whether a group without any respiratory protection (which highly mirrors real-world practice) might have helped quantify the baseline risk of infection. Similar studies in the inpatient setting could also help optimize practice.


Radonovich LJ, Simberkoff MS, Bessesen MT, et al. N95 respirators vs medical masks for preventing influenza among health care personnel: a randomized clinical trial. JAMA 2019;322(9):824-833.