By Gary Evans, Medical Writer
In a time of respiratory viruses — including the still-simmering SARS-CoV-2 — it always seems to come down to masks vs. respirators for healthcare workers. An advisory panel to the Centers for Disease Control and Prevention (CDC) recently completed draft isolation guidelines for respiratory patients, but got a thumbs down and a loaded question for their trouble: “Should N95 respirators be recommended for all pathogens that spread by the air?”
That question and several others were in a Jan. 23, 2024, letter1 from the CDC to its Healthcare Infection Control Practices Advisory Committee (HICPAC), which approved a draft of air transmission isolation guidelines on Nov. 2, 2023. HICPAC dropped the controversial droplet/airborne dichotomy in favor of a continuum approach with three tiers of air precautions dubbed Routine, Special, and Extended. (For more information, see the related story in the February 2024 issue of Hospital Employee Health.)
However, the CDC did not approve the recommendations and sent a formal letter asking the panel to reconsider and clarify several aspects of the guidelines. The CDC sought answers and insights on several issues involving surgical masks and respirators worn by healthcare workers.
The question about universal N95 use was asked concerning draft Routine Air Precautions, which recommend healthcare workers wear a surgical mask. The other two tiers of air precautions in the draft call for respirators to protect healthcare workers and patients.
“Routine Air Precautions are focused on reducing transmission of common, often endemic, respiratory pathogens that spread predominantly over short distances based on observed patterns of transmission, and for which individuals and their communities are likely to have some degree of immunity,” the HICPAC draft guidelines state.2
In the letter, the CDC questioned whether such a mask-only category should be recommended, asking the panel if all air transmission categories should call for respirators.
Although some could see this as excessive and possibly even counterproductive, the push for respirators seems to be coming from the millions of people with long COVID and the disability community in general.
An explanatory CDC blog co-written by John Howard, MD, chief of the CDC’s National Institute of Occupational Safety and Health (NIOSH), said, “There is concern that SARS-CoV-2 would revert to routine air precautions because, at this time, it is no longer new and emerging. There is also concern that adverse outcomes associated with substantial morbidity, such as long COVID, would not be considered in determining whether to apply routine or special air precautions because they might not be considered as representing severe disease.”3
Tom Talbot, MD, president of the Society for Healthcare Epidemiology of America, agreed this was the likely issue, saying, “I think what’s really fueling a lot of this angst is specifically around COVID and precautions.”
A former paramedic with long COVID was unequivocal when asked whether it would be better to err on the side of caution and require healthcare workers to wear N95s for all patients hospitalized with a respiratory infection.
“I would say explicitly ‘yes’ because one of the issues that we’re seeing with long COVID is what it does to the immune system,” said Karyn Bishof, BS, founder of the COVID-19 Longhauler Advocacy Project. “The impacts are similar to what we see in HIV in T cell depletion and causing immunodeficiency. Some of the high cases of influenza and respiratory syncytial virus [RSV] we have seen since fall are because people’s immune systems have taken such an extreme hit from getting long COVID.” (For more information, see the related Q&A in this issue.)
‘Areas of Confusion’
The CDC letter told the panel to reconvene and answer several questions before the final draft is published for public comment in the Federal Register.
“Additional subject matter experts will be added to the workgroup to assist with preparing responses,” the CDC stated. “We feel these questions, largely related to when masks and respirators (such as N95) are recommended in healthcare settings, reflect concerns or areas of confusion that continue to be raised by stakeholders in response to the draft guideline.”
A part of the problem is that the massive tome of the 2007 CDC isolation guidelines is necessarily being written in two parts, with this framework put down first and then followed by the so-called appendix wherein each pathogen is designated within a category of precautions. Currently, it is unknown where COVID-19 will be placed in the newly formed air precautions.
In the HICPAC draft guidelines, the next tier up is Special Air Precautions, calling for the use of N95s by healthcare workers treating “patients with a respiratory pathogen, typically new or emerging, that is not observed or anticipated to spread efficiently over long distances (such as through ventilation systems), for which infection generally leads to more than mild illness, and where immunity (or vaccine) and effective treatment are not available,” the guidelines authors wrote.
The CDC asked the advisory committee to continue discussions on this and posed these questions: “Can the [HICPAC] workgroup clarify the criteria that would be used to determine which transmission by air category applies for a pathogen? For the category of Special Air Precautions, can you clarify if this category includes only new or emerging pathogens or if this category might also include other pathogens that are more established?”
“That’s where you’re getting to the nuance of this — where does SARS-CoV-2 fall based on the evidence? Where do other things fall?” Talbot asked. “I think there’s a lot of fear that the core recommendations may mean something different to folks based on their review of the evidence.”
The final and most restrictive of the air transmission tiers is Extended Air Precautions, which are to be used when healthcare workers wearing respirators are caring for patients infected “with pathogens that are observed to spread efficiently across long distances and over extended times, such that room air needs to be contained.”
The panel did not give examples of pathogens, but an obvious virus that fits this category is measles.
SARS-CoV-2 Conundrum
During the height of the pandemic, there was considerable debate about whether SARS-CoV-2 was truly airborne outside of aerosol-generating procedures, but both the CDC and the World Health Organization eventually conceded, and the supposition that it was spread by droplets within a few feet of the patient was dropped. The question remains: In which of these tiers of precautions will SARS-CoV-2 be placed? One could argue that it has become endemic but capable of surges, as we have seen currently with the JN.4 omicron subvariant. Many surveillance systems have been shut down, and healthcare epidemiologists are relying on wastewater data to detect community levels. Poor vaccine uptake, the ability of the virus to cause breakthrough infections, and the looming threat of long COVID all make the situation with SARS-CoV-2 somewhat dicey.
“This is such a complex issue, and different pathogens differ, so there’s been a lot of application of single points of evidence to these questions, which I don’t think is appropriate,” Talbot said. “There are pieces all along the spectrum from basic science to controlled science to other studies that are important to inform, but it’s not the only absolute. I think this question of N95s for everything all the time is not accounting for important and pragmatic data looking at protection. There are studies looking at other respiratory illnesses on that question, and in the actual real world — what I call the dirty laboratory of healthcare, where we’re dealing with [patients] and people — it showed that there was no difference in effect with the different PPE [personal protective equipment] types.”
A HICPAC draft appendix to the guidelines reached a similar conclusion. “Laboratory studies have demonstrated that N95 respirators provide better filtration than surgical or medical masks,” the appendix authors wrote. “In the real world, among healthcare personnel caring for patients in healthcare settings, the peer-reviewed evidence is inconsistent on whether the outcomes of respiratory illness or infection are different among N95 respirator users and medical/surgical mask users.”4
One possibility is that the greater efficacy of the respirator is eroded by discomfort and noncompliance. The appendix noted that “difficulty breathing, headaches, and dizziness; skin barrier damage and itching; fatigue; and difficulty talking were more frequently reported among N95 respirator users. … It is important to note that while these adverse events are not considered severe, they might impact N95 respirator fit, healthcare personnel comfort, and their adherence to N95 respirator use.”
The CDC wrote the appendix at the request for more information by HICPAC. The result is an exhaustive review of the medical literature on the efficacy of masks and respirators worn by healthcare workers. Although it seems safe to say that the N95 provides better filtering protection if appropriately fit-tested and worn properly to care for patients with respiratory infections, caveats and variables abound in comparing studies and real-world use.
The appendix concluded with a commonsense confounder: “Future studies examining the effectiveness of N95 respirators and masks would be enhanced by clearly identifying whether healthcare personnel exposures and infections are patient-related rather than co-worker or community-related.”
Despite the blurred science, the blog post by Howard and co-author Dan Jernigan, MD, a CDC medical epidemiologist, argued for making an N95 or higher level of respirator the clear choice in the final draft guidelines.
“Another issue relevant to preventing transmission through air is to make sure that a draft set of recommendations cannot be misread to suggest equivalency between face masks and NIOSH-approved respirators, which is not scientifically correct nor the intent of the draft language,” Howard and Jernigan wrote. “Although masks can provide some level of filtration, the level of filtration is not comparable to NIOSH-approved respirators. Respiratory protection remains an important part of personal protective equipment to keep healthcare personnel safe.”
The authors of the CDC letter asked another question that came up in HICPAC discussions: “Is the current guideline language sufficient to allow for voluntary use of a NIOSH-approved N95 (or higher-level) respirator? Should the document include a recommendation about healthcare organizations allowing voluntary use?”
In an explanatory text in the draft guidelines, HICPAC clarified that healthcare workers may go beyond the guidelines and wear an N95 respirator for routine air isolation “per existing federal regulations.”
This is following Occupational Safety and Health Administration requirements for respiratory protection programs, but several HICPAC members said it was confusing to put it in a CDC guideline. Allowing PPE beyond the recommended level of protection could send a mixed message about what level is safe, they said.
Another question the CDC asked HICPAC to weigh in on is: “[Should] source control be recommended at all times in healthcare facilities?” This is apparently about the widespread return to universal masking by healthcare workers and incoming patients this respiratory season. This practice was dropped at the end of the public health emergency last May. The HICPAC draft guidelines call for source control with masks when patients in air transmission precautions leave their rooms. Universal masking is not recommended by the CDC, so the practice may vary widely by individual facility.
“Seeking healthcare is inaccessible due to the risks — there are no mitigation efforts going on,” Bishof said. “People like myself who are high risk, who are immunocompromised, who have all these health conditions — even if we mask, nobody else in these facilities is masking. And so, there’s a delay in seeking healthcare. There’s a delay in diagnostics. There’s a delay in treatment because people think it’s safer to suffer at home than go in settings that aren’t safe for us at the moment.”
REFERENCES
- Kallen A. CDC letter to HICPAC. Jan. 23, 2024. https://www.cdc.gov/hicpac/pdf...
- Centers for Disease Control and Prevention. 2024 Guideline to Prevent Transmission of Pathogens in Healthcare Settings. 2023. https://www.cdc.gov/hicpac/pdf...
- Jernigan D, Howard J. CDC Update on the Draft 2024 Guideline to Prevent Transmission of Pathogens in Healthcare Settings. Jan. 23, 2024. https://blogs.cdc.gov/safeheal...
- Healthcare Infection Control Practices Advisory Committee. Draft Healthcare Personnel Use of N95 Respirators or Medical/Surgical Masks for Protection Against Respiratory Infections: A Systematic Review and Meta-Analysis. Nov. 2, 2023. https://www.cdc.gov/hicpac/pdf...
An advisory panel to the Centers for Disease Control and Prevention recently completed draft isolation guidelines for respiratory patients, but got a thumbs down and a loaded question for their trouble: “Should N95 respirators be recommended for all pathogens that spread by the air?”
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