Updated WHO COVID prevention guidance may endanger rather than protect, some experts say

N95s and medical masks

Maridav / iStock

The World Health Organization's (WHO's) newly updated COVID-19 prevention and control guidelines purport to protect healthcare workers, patients, and the community, but some experts say they may encourage risky behavior by propagating long-disproven ideas about how viruses spread.

"I think they put healthcare workers and patients and the community at significant risk," said Lisa Brosseau, ScD, CIH, an expert on respiratory protection and infectious diseases and a CIDRAP research consultant.

One of the main problems, said Raina Macintyre, MBBS, PhD, professor and head of the biosecurity program at the Kirby Institute in Sydney, Australia, is that the document doesn't incorporate many of the lessons learned during the pandemic—such as the major role of COVID-19 spread among people with no symptoms.

"The guidelines suggest using symptoms to screen people," she said via email. "This is seen in health guidelines in many countries—emphasis on symptoms ('wear a mask if you feel unwell'), when we know a substantial proportion of transmission is asymptomatic, which is a major rationale for universal masking in high-transmission settings."

Similarly, David Michaels, PhD, MPH, an epidemiologist and professor at George Washington University School of Public Health and a former administrator at the US Occupational Safety and Health Administration (OSHA), said the guidelines don't directly address the modes of COVID-19 transmission.

"I was very disappointed," he told CIDRAP News, referring to the WHO's adherence to what he calls "droplet dogma,'" or the misguided belief that SARS-CoV-2 spreads mainly through droplets rather than aerosols. "It hasn't fully recognized the concept that this novel coronavirus is airborne.

Masks, respirators not equivalent

Nor does the document fully recognize that N95 respirators offer better protection against the virus than medical, or surgical, masks. Rather, it says the Guideline Development Group (GDG) "considered the evidence for particular respirators versus medical masks and agreed that the strength of this evidence was insufficient to recommend one mask over another except in some specific conditions."

Masks are good as source control for coughing and sneezing, but if a virus is truly airborne, as we think this coronavirus is, while it's useful, it's not adequately protective.

David Michaels, PhD, MPH

Brosseau said, "There's so much laboratory and workplace research that shows how much better a respirator works than a mask. Medical masks and respirators don't have the same filters, and medical masks leak through their filters a lot. They may be similar in capturing large particles, but in small particles, medical masks are very leaky, so it doesn't really matter how it fits on your face, many of the small particles are still going to exit through the filter and around the facepiece."

Michaels agreed, saying, "Masks are good as source control for coughing and sneezing, but if a virus is truly airborne, as we think this coronavirus is, while it's useful, it's not adequately protective."

Healthcare workers should demand better, Macintyre said: "Would a construction worker accept being told that a safety helmet that was 1.99 times worse than another was good enough for them because someone decided being almost twice as bad was 'equivalent' "? [See related content, "CDC seeks to update guidance to reflect recognition of aerosol viral spread," below this story.]

Michaels said he understands that the guidelines were the work of a committee that had to reach consensus. "But at the same time, this is a really important document that has global implications," he said. "There was a decision made to avoid requiring the best protection for workers, and that's unfortunate."

The 1-meter rule and other contradictions

Macintyre pointed out that the guidelines recommend physical barriers, such as Plexiglass screens, which she said some evidence suggests may be detrimental because they impede airflow. "The use of the PICO [Patient or problem, Intervention or exposure, Comparison or Control, and Outcomes] framework tends to ignore or trivialize engineering and aerosol science research, when much of the key science around transmission of respiratory pathogens does require research from disciplines other than medicine," she said.

Healthcare workers wearing protective equipment
US Navy, Jake Greenberg / Flickr cc

The WHO recommends that everyone in healthcare settings stay at least 1 meter (3.3 feet) apart, when possible. "There's no discussion of where this 1 meter, this 39 inches, comes from," Michaels said. Physical distancing is "one of the many precautions that are worth implementing, because with aerosol transmission, they'll be more exposure closer to the source than further away, but why use 1 meter or 2 meters or any other number without providing any rationale, any evidence?"

The guidelines also introduce the term "targeted continuous." "Use of masks is either targeted or continuous but cannot be both—which seems a deliberate attempt to introduce new terminology that makes it harder for advocates of occupational safety to ask for continuous protection," Macintyre said.

Most WHO recommendations that involve airborne pathogens—including ventilation—were tagged as "low certainty," which Macintyre said seems selective, when other recommendations with less evidence were deemed "good practice."

So they're willing to talk about laboratory studies for better-fitting masks, but they're not willing to talk about laboratory studies for performance of respirators?

Lisa Brosseau, ScD, CIH

What stood out most to Brosseau is the guidelines' discussion of how to make medical masks fit better, when they're not designed to prevent small particles from escaping. "No one has ever cared that a medical mask actually fits, because it's not designed to fit, and you don't evaluate a mask for fit," she said.

"You finally get WHO talking about getting them to fit better and making recommendations on the basis of almost no data," she said. "So they're willing to talk about laboratory studies for better-fitting masks, but they're not willing to talk about laboratory studies for performance of respirators? If they're worried about the fit of a medical mask, why is it that they dismiss fit-testing respirators, where it really does matter?"

Longstanding resistance to respirators

Healthcare worker donning N95
Samara Heisz / iStock

The bias against respirators has been evident for years, dating back to 1980s tuberculosis outbreaks in the early HIV/AIDS epidemic, Brosseau said.

"OSHA even proposed an emergency temporary standard that required the use of respirators for healthcare workers who were caring for tuberculosis patients, and the CDC [Centers for Disease Control and Prevention] and the American Hospital Association and the AMA [American Medical Association] and the rest lobbied against an OSHA standard. That standard was never promulgated as a permanent standard, which is unfortunate because it would have been useful during the pandemic," she said.

Macintyre concurs. "The ideology that a surgical mask is as good as an N95 respirator has been propagated for a very long time, during SARS [severe acute respiratory distress syndrome] in 2003," she said. She cited the different results seen in hospitals in two Canadian cities amid SARS (those in Toronto used surgical masks, while those in Vancouver used N95s, resulting in a large epidemic and many deaths only in Toronto).

"And again during the influenza pandemic of 2009 and reaching a fevered pitch during the COVID-19 pandemic," she continued. "The sum of evidence clearly shows that a surgical mask is not as protective as an N95."

Brosseau said those opposed to respirators have noted that they can be uncomfortable to wear and have argued that they aren't very accessible in low-income countries. Respirators weren't designed to be worn for hours on end without a break, she said, adding that low-income countries did manage to acquire respirators during the pandemic and that they can be reused multiple times before disposal.

The argument for universal respirator use

Macintyre, Michaels, and Brosseau all say they support universal respirator use in healthcare settings, especially during periods of high respiratory virus community transmission.

"I think it depends on the overall risk in the region, but certainly universal [respirator use] in periods of increased risk is absolutely vital, because you can't predict who will be infectious," Michaels said.

Using respiratory protection only when in close contact with patients diagnosed as having COVID-19 or during aerosol-generating procedures (AGPs) ignores evidence that aerosols can waft through the entire indoor environment for prolonged periods, the experts say. "The guidelines mistakenly attribute the highest risk to AGPs, but studies show that coughing generates more aerosol than an endotracheal intubation," Macintyre said.

Brosseau said the data support universal respirator use among healthcare workers, at a minimum. "A patient might spend an hour, hour and a half, in a clinic, but a healthcare worker's exposure is continuous and ongoing, so they have a much greater chance of being exposed than visitors and patients," she said.

The guidelines mistakenly attribute the highest risk to AGPs [aerosol-generating procedures], but studies show that coughing generates more aerosol than an endotracheal intubation.

Raina Macintyre, MBBS, PhD

Visitors and patients who can tolerate wearing a respirator should be encouraged to do so, especially during the respiratory virus season, she said: "Even a non–fit-tested respirator is better than a medical mask. If we take what we learned from the pandemic… I think we could probably reduce the burden of respiratory and viral disease overall." Brosseau was the lead author of a two-part commentary on respiratory protection published in 2021 by CIDRAP News.

Michaels agreed, saying that a culture shift is possible and cited the relatively recent use of universal gloving. "During the HIV/AIDS epidemic, OSHA required a bloodborne pathogen standard in healthcare facilities," he said. "Many people in the dental profession said, 'How can we work if you make us wear gloves?' Fortunately, OSHA did not accept their comments, and no one thinks anymore that universal gloving is not an appropriate precaution."

CDC seeks to update guidance to reflect recognition of aerosol viral spread

The US Centers for Disease Control and Prevention (CDC) has asked the Healthcare Infection Control Practices Advisory Committee (HICPAC) to clarify its guideline on isolation precautions to reflect the "widespread recognition" that respiratory viruses spread primarily through aerosols, according to a CDC blog post this week.

"The observation that infections have characteristic distances over which they can be transmitted reflects factors including greater concentrations of infectious respiratory particles closer to infected individuals and differences in pathogen-specific factors such as the inhaled dose required to cause infection and the amount of time that a specific pathogen is able to remain infective," the blog post reads.

In particular, the CDC is seeking guidance on whether N95 respirators should be mandatory in healthcare settings and, if so, in what circumstances. In November, HICPAC held a public meeting in Atlanta on the CDC's draft recommendations and, once it receives clarification, it will post the guideline in the Federal Register for public comment.

The proposed new guideline categories are Special Air Precautions (recommends the use of N95s during care of patients with pandemic or emerging respiratory viruses); Routine Air (requires masking and eye precautions to protect against endemic respiratory pathogens), and Extended Air Precautions (for use when caring for patients with pathogens that spread through aerosols).

Developing core concepts

Tom Talbot, MD, chief hospital epidemiologist at Vanderbilt University Medical Center and president of the Society for Healthcare Epidemiology of America (SHEA), told CIDRAP News that the request is a normal part of an iterative process to ensure that the guideline protects patients and healthcare workers.

SHEA, which works with hospitals to implement infection-prevention programs, policies, and actions in healthcare systems, uses the CDC infection-control guidelines extensively.

Talbot also emphasized that, at this point, the work is focusing on the core concepts part of the guideline, which will be followed by detailed pathogen-specific guidance. "Once these get finalized, we'll work to implement these in healthcare settings across the country," he said.

He added that it's important to look at the guideline pragmatically: "We all work in what I call the 'dirty laboratory' of the hospital or healthcare, where there are many different pieces of things we have to put in place, what we call the hierarchy of controls, recognizing that all these pieces of infection prevention, none of them are perfect, because we're dealing with a dirty laboratory with people who are busy."

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