N95 should be standard for all COVID-19 inpatient care, say experts

Surgical masks are not equivalent to N95 respirators for reducing risk of infection and should not be regarded as interchangeable when N95 respirators are in shortage, especially in the setting of COVID-19 inpatient care.

Such is the position that five experts hold strongly in an editorial published in the Annals of Internal Medicine. [Ann Intern Med 2020;doi:10.7326/M20-2623] 

While all guidelines recommend N95 respirators in aerosol-generating procedures (AGPs), guidance differs with regard to the use of N95 vs surgical masks for frontline healthcare workers (HCWs) caring for COVID-19 patients — particularly when AGPs are not involved.

“[We] strongly support the use of N95 respirators for all inpatient care of patients with COVID-19, not only during AGPs,” stated the experts led by Dr Harry Peled of St. Jude Medical Center in Fullerton, California, US.

“Use of N95 respirators to protect HCWs should not merely be a preference or a recommendation based on availability,” they advocated. “The data indicate that it should be the standard for all inpatient COVID-19 management.”

The experts made the case that existing evidence do not support surgical masks as equivalent to N95 in protection and the data are often misinterpreted.

Surgical mask ≠ N95 respirators

Taking a frequently cited meta-analysis as example, the authors showed no significant difference overall in the protection by N95 vs surgical mask against influenza. [J Evid Based Med 2020;13:93-101] However, the experts noted that one of the studies by Radonovich et al. included in the analysis was an outpatient study assumed as an inpatient study while another household contact study was also included. [JAMA 2019;322:824-833]

Similarly, another meta-analysis which suggested that surgical masks and N95 respirators were similarly effective against viral respiratory infection also included the outpatient study from Radonovich and colleagues. [Influenza Other Respir Viruses 2020;14:365-373]

“Ultimately, these recent meta-analyses mixed outpatient and inpatient data and underestimated the true benefit of N95 masks in the inpatient setting,” Peled and co-authors pointed out.

“It is apparent that the risk for HCW infection is related to duration and magnitude of exposure,” they explained. “A COVID-19 inpatient unit with multiple patients coughing and breathing will have far higher exposure to droplets, resuspended droplets, and aerosols than an outpatient setting.”

Adding to the confusion are some guidelines which referenced these studies to support recommendations on PPE use for COVID-19. ˜ 

“The data the guidelines referenced do not support the conclusion that medical masks are equivalent to N95 respirators in reducing risk for infection,” stated Peled and co-authors.

Potential airborne threat

It is now established that SARS-CoV-2, the virus causing COVID-19, is more infectious and lethal than the influenza virus. With a reproductive number (R₀) of 2.3, SARS-CoV-2 is approximately twofold more transmissible than the seasonal influenza which has an R₀ of 1.8. [Intensive Care Med 2020;46:854-887]

“Therefore, guideline recommendations in the COVID-19 era should take a more precautionary approach for the inpatient setting, especially when no vaccine or effective pharmacologic treatment exists,” stressed the experts.

There is also emerging evidence which suggests that SARS-CoV-2 may transmit through aerosol, though whether this constitutes a dominant route of transmission remains unclear.   

“We need more focused studies that evaluate SARS-CoV-2 transmission in the inpatient setting,” said Peled and co-authors. “The guideline recommendations stating equivalency of N95 and medical masks for COVID-19 inpatient care are based on inappropriate extrapolation of studies and may not account for the growing body of evidence surrounding aerosol transmission of SARS-CoV-2.”

To complicate matters, due to claims from several organizations that surgical masks are acceptable, healthcare administrators may assume these as a valid reason to deny HCWs in COVID-19 units the access to N95 masks and instead reserve them for AGPs.

“Recognizing that medical masks are substandard will empower our society to allocate resources to ensure availability of N95 respirators,” stated the experts.

“Instead of allowing our HCWs to work in substandard protection, countries should focus on allocating resources to increase production of medical masks and N95 respirators.”