October 19, 2023 / Ed Rutkowski

Webinar Rallies Opposition to Draft Guidelines on Aerosol-Transmissible Diseases in Healthcare

On Friday, Oct. 13, a diverse group of professionals, scientists, advocates, and other stakeholders offered detailed criticisms of CDC's intent to consider guidelines that would recommend healthcare workers wear surgical masks in contexts where science supports the use of N95 respirators. In a webinar hosted by the Rutgers School of Public Health and the New York and New Jersey Occupational Safety and Health Center, speakers described the science of aerosol-transmissible diseases and prompted attendees to offer recommendations for improving the guidelines.

The new guidelines, which are being developed by a workgroup of the Healthcare Infection Control Practices Advisory Committee (HICPAC), are intended to replace the current "Guideline for Isolation Precautions: Preventing Transmission of Infectious Agents in Healthcare Settings" established in 2007.

During the webinar, Jane Thomason, CIH, an AIHA member who serves as lead industrial hygienist for National Nurses United (NNU), described the guideline development process as "largely happening behind closed doors." The workgroup began its deliberations in February 2022, but access to its meetings is restricted, and no draft of the guidelines has been made public. NNU obtained summaries of workgroup meetings through Freedom of Information Act requests. "Once it became clear that CDC was planning to weaken guidance, NNU started sounding the alarm," Thomason said.

Much of what is known about the workgroup's intent stems from its presentation at a meeting of the full HICPAC membership on June 8. CDC posted a PDF of the presentation to the agency's website only after pressure from NNU, Thomason said. Other presentations are available from the CDC website.

The presentation suggests that the workgroup's new guidelines will emphasize two transmission pathways for infectious diseases: air and touch. At first glance, this change is an improvement over the 2007 guidelines, which are based on an inaccurate distinction between droplet and airborne transmission. But it still falls far short of current scientific understanding, Thomason said. "HICPAC's workgroup is failing to recognize the role that inhalation plays in aerosol transmission and the impact of other factors such as time, dose, activity, and environmental factors," Thomson explained. The presentation also included what Thomason described as a "biased and incomplete" review of evidence for the effectiveness of N95 respirators compared to surgical masks.

Elsewhere, the presentation identifies tiers of protection. For "routine" precautions, which would apply to pathogens such as seasonal influenza and seasonal coronavirus, surgical facemasks are recommended, which contradicts the presentation's recognition of air as a pathway of transmission, Thomason said. Precautions for novel pathogens such as MERS, SARS-CoV-1, and pandemic-phase respiratory viruses—a group that includes SARS-CoV-2 and influenza—recommend an N95 respirator but not the use of an airborne infection isolation room, or AIIR.

"This is a step down from current practice," Thomason said. "Novel pathogens need an airborne infection isolation room because we don't know yet how they transmit."

According to Thomason, HICPAC's planned vote on the workgroup's recommendations at its August meeting has been delayed because of NNU's advocacy. The vote is now scheduled to occur at the next HICPAC meeting, which is scheduled to be held online on Nov. 2 and Nov. 3. Public comments are typically allowed at HICPAC meetings, but those who wish to speak must submit a request on the CDC website, the number of speakers is limited, and each speaker will have only three minutes. Thomason encouraged webinar attendees to register and called on CDC to release the draft guidelines. "The lack of a draft severely limits the public's ability to engage with this process," she said.

If approved by HICPAC, the workgroup's guidelines will be reviewed by CDC and then published in the Federal Register.

Other speakers at the webinar included Dr. Donald Milton, a professor at the University of Maryland School of Public Health, who summarized the science of aerosol transmission and studies supporting the effectiveness of N95 respirators. Eric Berg, the deputy chief of health for Cal/OSHA, stated that the HICPAC workgroup's recommendations are contrary to state law and would cause confusion at California hospitals. William Bahnfleth from Pennsylvania State University described relevant ventilation standards for healthcare facilities, and Lisa Brosseau, ScD, CIH, from the University of Minnesota discussed personal protective equipment for healthcare workers.

Throughout the webinar, nurses and members of the public shared personal stories about the effects of the COVID-19 pandemic. Some had lost loved ones to the disease because, they said, of insufficiently protective guidance informed by incorrect notions about how COVID-19 spreads.

Recordings of these webinar presentations are available from the Rutgers School of Public Health website. AIHA, a cosponsor of the webinar, submitted a letter (PDF) to CDC in July that described the HICPAC workgroup's new guidelines as "grossly deficient." Additional information is available from the NNU website.

Ed Rutkowski

Ed Rutkowski is editor in chief of The Synergist.


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