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

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.

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."

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

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.

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."