Patients and family members of people with long COVID, as well as other disabilities and immunodeficiencies, have had their voices heard by the Centers for Disease Control and Prevention (CDC). Citing pushback from such stakeholder groups, the CDC rejected new recommendations for air transmission precautions by its infection control advisory panel, asking it to consider with expert consultation this question: “Should N95 respirators be recommended for all pathogens that spread by the air?”
That question and several others were in a Jan. 23, 2024, letter from the CDC to its Healthcare Infection Control Practices Advisory Committee (HICPAC), which approved a draft of air transmission isolation guidelines on Nov. 2, 2023.1 HICPAC dropped the controversial droplet/airborne dichotomy in favor of a continuum approach with three tiers of air precautions dubbed routine, special and extended. (See Hospital Infection Control & Prevention, January 2024.)
The aforementioned question about universal N95 use was asked regarding draft Routine Air Precautions, which recommend healthcare workers wear a surgical mask. The other two tiers of air precautions in the draft call for N95 or higher-level 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
This first portion of the update of the 2007 isolation guidelines was designed to provide a framework, with specific respiratory pathogens to be designated later for the three air transmission categories. This approach proved to be problematic, since it opened the question of where SARS-CoV-2 would be placed, and specifically whether it would call for masks or respirators to be worn by healthcare workers.
In the letter, the CDC questioned whether such a mask-only “routine” 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 N95 or higher-level respirators seems to be driven by at-risk patients afraid to seek healthcare, as well the accumulating data that COVID-19 reinfections increase the risk of developing long COVID.
“The CDC seems to be prudently re-reviewing the draft guidance based on public interests, which demonstrates their openness to receiving constructive feedback from the vested public,” says Tania Bubb, PhD, RN, CIC, FAPIC, president of the Association for Professionals in Infection Control and Epidemiology (APIC). “APIC will continue to wait until CDC releases the recommendations before commenting on any changes.”
An explanatory CDC blog co-written by John Howard, MD, chief of the CDC’s National Institute of Occupational Safety and Health (NIOSH), says, “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 (SHEA), agreed this was the likely issue, saying, “I think what’s really fueling a lot of this angst is specifically around COVID and precautions. 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? 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.”
‘Please Do the Right Thing’
A former paramedic with long COVID was unequivocal when asked whether it would be better to err on the side of caution and have healthcare workers 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,” says Karyn Bishof, BS, founder of the COVID-19 Longhauler Advocacy Project. “The impacts are similar to what we see in HIV (human immunodeficiency virus) in T cell depletion and causing immunodeficiency. [In my opinion], 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.”
The aforementioned blog by Howard and coauthor Dan Jernigan, MD, a CDC medical epidemiologist, argued that the guidelines must not muddy the waters on this issue so that surgical masks are somehow seen as equal protection to respirators.
“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 facemasks and NIOSH-approved respirators, which is not scientifically correct nor the intent of the draft language,” the blog authors 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 (PPE) to keep healthcare personnel safe.”
The CDC blog received scores of public comments, with one dated Jan. 26, 2024, saying, “I am a nurse who used to work in the operating room before I was disabled by long COVID. The use of N95 masks [is] crucial to prevent the transmission of pathogenic and/or disabling viruses.”
Other comments on the same blog thread included:
• “I am sure that most people who commented here never worked 12-hour shifts in N95 respirators. It is physically and emotionally exhausting, it causes headaches and decreases concentration [until] the end of the shift. Skin irritation is a problem as well. Hourly breaks should be allowed. Who will provide such breaks for overworked nurses in understaffed facilities?”
• “We need N95 or better precautions in all healthcare settings, due to the high circulating levels of the BSL-3 pathogen, SARS-CoV-2. As someone at high risk of COVID and long COVID, I want to be able to access healthcare without incurring a severe risk of disability when doing so.”
• “[Long COVID] is the real long-term threat with wide-ranging consequences, and the chance of long COVID escalates with each reinfection from acute COVID. Please do the right thing, morally and ethically. Please.”
Risk of Long COVID
One of the first researchers to document the cumulative risk of acquiring long COVID via SARS-CoV-2 reinfection is Ziyad Al-Aly, MD, chief of research and development and director of the Clinical Epidemiology Center at the VA St. Louis Health Care System, as well as clinical epidemiologist at Washington University. Al-Aly also serves on the White House Intra-agency Policy Committee on Long Covid.
“Reinfection is the most common form of SARS-CoV-2 infection nowadays,” he tells Hospital Infection Control & Prevention. “The evidence is compellingly clear; reinfection is not inconsequential. Even if they did not get long COVID after first infection, people may still get long COVID after reinfection. And people who already have long COVID may experience worsening of their health problems after reinfection.”
Asked about masks, respirators, and other infection control issues for SARS-CoV-2, Al-Aly says we have gained the knowledge to prevent healthcare transmission but there is a lost sense of urgency.
“Getting SARS-CoV-2 infection in a healthcare setting should be a zero-event,” he says. “It is completely avoidable [with] proper masking, air filtration, isolation, etcetera. Neither patients nor healthcare workers should be unnecessarily exposed to this hazard. SARS-CoV-2 infection remains more consequential than a flu infection, yet we trivialize it. We have become irrationally oblivious and complacent about the danger it poses to our healthcare workers and to our patients. I see healthcare systems worried more about MRSA (methicillin-resistant Staphylococcus aureus), C. diff, and the flu than they are worried about SARS-CoV-2. I don’t think this is logical.”
Moreover, the risk of developing long COVID incrementally increases with each reinfection, according to Al-Aly and colleagues in a study that found this cumulative effect continued for up to three reinfections.4 Comparing a group who had been reinfected, some multiple times, to those that had not been reinfected, “we specifically showed that two infections are worse than one and three infections are worse than two,” he explained in a Grand Rounds talk.5 “Don’t interpret this as the second infection is more severe than the first. What we're saying is that, cumulatively, the adverse health effects from two infections are worse than only one; the adverse health effects from three infections are worse than two. Reinfection remains consequential (as a risk for long COVID) at least up to three infections.”
The protective effect of vaccination was not demonstrated in Al-Aly’s study, since the cumulative risk of long COVID was similar in vaccinated or naturally infected people who were reinfected.
“The mechanisms underpinning the increased risks of death and adverse health outcomes in reinfection are not completely clear,” the authors concluded. “Previous exposure to the virus may be expected to hypothetically reduce risk of reinfection and its severity; however, SARS-CoV-2 is mutating rapidly and new variants and subvariants are replacing older ones every few months. Evidence suggests that the reinfection risk is especially higher with the Omicron variant, which was shown to have a marked ability to evade immunity from previous infection. Any protection from previous infection (against reinfection and its severity) also wanes over time; evidence suggests that protection from reinfection declined as time increased since the last immunity-conferring event in people who had previously been infected with SARS-CoV-2, regardless of vaccination status.”
However, Al-Aly touted a Swedish study that did show a vaccine-protective effect against long COVID in people vaccinated before their first infection. That study in adults found that COVID-19 vaccination — before initial SARS-CoV-2 infection — is protective against long COVID in a stepwise fashion, from 21% for one dose, 59% for two doses, and a 73% for three or more doses.6 An accompanying editorial said the study shows that COVID-19 vaccines “have a clear and clinically important protective effect against post-COVID-19 condition[s].”7
“Yes, vaccines reduce that risk,” Al-Aly says. “It is unfortunate to see that the appetite for vaccines has dwindled dramatically. I think this is largely due to pandemic fatigue and poor public health messaging. I think one of the main or key motivators for vaccination should be its role in reducing the risk of long COVID, which in some patients may be severe and disabling and for which we have no curative treatment.”
Thus, even though COVID-19 may have dropped from pandemic to endemic status, its ability to cause breakthrough infections and the threat of long COVID in an estimated one in five acute cases has complicated HICPAC’s task considerably.8
‘Areas of Confusion’
The CDC letter to HICPAC told the panel to reconvene and answer several questions before the final draft is resubmitted for review and eventually 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 N-95) are recommended in healthcare settings, reflect concerns or areas of confusion that continue to be raised by stakeholders in response to the draft guideline.”
In the HICPAC draft guidelines, the next tier up from Routine Air Precautions is Special Air Precautions. This tier calls for N95s or higher-level respirators for 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 state.
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?”
The final and most restrictive of the air transmission tiers in the draft 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.”
Poor vaccine uptake, the ability of the coronavirus to cause breakthrough infections, and the looming threat of long COVID all make the situation with SARs-CoV-2 somewhat dicey. Some hospitals have returned to universal masking by healthcare workers and incoming patients this respiratory season. Universal masking is not currently recommended by the CDC, so the practice may vary widely by individual facility. Thus, those with long COVID and other risk factors report dismay at realizing that they seem to be the only ones wearing masks when they seek medical treatment.
“Healthcare is inaccessible due to the risks — there are no mitigation efforts going on,” Bishof says. “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.”
‘Real World’ Woes
“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 types.”
In that regard, a HICPAC draft appendix to the guidelines reached a similar conclusion. According to the appendix, laboratory studies have shown that N95 respirators offer better filtration than surgical or medical masks.9 However, it adds that, “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.”
As some have noted, the greater efficacy of the respirator can be undermined by discomfort that contributes to noncompliance. The appendix notes 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 concludes 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 coworker- or community-related.”
REFERENCES
- Kallen A. CDC letter to HICPAC Workgroup. Published Jan. 23, 2024. https://www.cdc.gov/hicpac/pdf/CDC-Letter-to-HICPAC-Workgroup-Blog-508.pdf
- Centers for Disease Control and Prevention. Draft 2024 Guideline to Prevent Transmission of Pathogens in Healthcare Settings. https://www.cdc.gov/hicpac/pdf/DRAFT-2024-Guideline-to-Prevent-Transmission-of-Pathogens-2023-10-23-508.pdf
- Jernigan D, Howard J. A CDC update on the draft 2024 Guideline to Prevent Transmission of Pathogens in Healthcare Settings. Published Jan. 23, 2024. https://blogs.cdc.gov/safehealthcare/draft-2024-guideline-to-prevent-transmission-of-pathogens-in-healthcare-settings/
- Bowe B, Xie Y, Al-Aly Z. Acute and postacute sequelae associated with SARS-CoV-2 reinfection. Nat Med 2022;28:2398-2405.
- YouTube. Update on Long Covid. UCSF Department of Medicine. Published Dec. 15, 2023. https://www.youtube.com/watch?v=rMt6ZV-hHSE
- Lundberg-Morris L, Leach S, Martikainen J, et al. Covid-19 vaccine effectiveness against post-covid-19 condition among 589 722 individuals in Sweden: Population based cohort study. BMJ 2023;383:e076990.
- Sivan M, Ormerod M, Maini R. Does timely vaccination help prevent post-viral conditions? BMJ 2023;383:2633.
- Centers for Disease Control and Prevention. Nearly one in five American adults who have had COVID-19 still have “long COVID.” Last reviewed June 22, 2022. https://www.cdc.gov/nchs/pressroom/nchs_press_releases/2022/20220622.htm
- Centers for Disease Control and Prevention. Draft Healthcare Personnel Use of N95 Respirators or Medical/Surgical Masks for Protection Against Respiratory Infections: A Systematic Review and Meta-Analysis. https://www.cdc.gov/hicpac/pdf/HCP-N95Mask-SLR-MainAppendix-2023-11-01-Draft-508.pdf
Citing pushback from stakeholder groups, the Centers for Disease Control and Prevention rejected new recommendations for air transmission precautions by its infection control advisory panel, asking it to consider with expert consultation this question: “Should N95 respirators be recommended for all pathogens that spread by the air?”
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