Study Comparing Surgical and N95 Masks Sparks Concern - Medscape

A randomized proceedings indicating that surgical masks are not inferior to N95 masks successful protecting healthcare workers against COVID-19 has sparked planetary criticism.

The study’s elder writer is John Conly, MD, an infectious illness specializer and prof astatine the Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada, and Alberta Health Services. The findings are not accordant with those of galore different studies connected this topic.

Commenting astir Conly's survey connected Twitter, Eric Topol, MD, editor-in-chief of Medscape, wrote, “It’s woefully underpowered but ruled retired a doubling of hazard for usage of aesculapian masks.”

The study, which was partially funded by the World Health Organization (WHO), was published online November 29 successful Annals of Internal Medicine.

This is not the archetypal clip that Conly, who besides advises the WHO, has been the taxable of controversy. He antecedently denied that COVID-19 is airborne — a presumption that is contradicted by beardown evidence. Last year, Conly made headlines with his arguable assertion that N95 respirators tin origin harms, including oxygen depletion and c dioxide retention.

A detailed examination by the Center for Infectious Disease Research and Policy (CIDRAP) astatine the University of Minnesota, Minneapolis, pointed retired galore technological flaws successful the study, including inconsistent usage of some types of masks. The survey besides examined healthcare workers successful 4 precise antithetic countries (Canada, Israel, Egypt, and Pakistan) during antithetic periods of the pandemic, which whitethorn person affected the results. Furthermore, the survey did not relationship for vaccination presumption and lacked a power group.

In a commentary published alongside the study, Roger Chou, MD, prof of medicine astatine Oregon Health & Science University successful Portland, said that the results were “not definitive,” with “a generous noninferiority threshold” that is really “consistent with up to a comparative 70% accrued hazard … which whitethorn beryllium unacceptable to galore wellness workers.”

Lead survey writer Mark Loeb, MD, prof of infectious diseases astatine McMaster University successful Hamilton, Ontario, Canada, defended the findings. “The assurance intervals astir this, that is, what the imaginable results could beryllium if the proceedings was repeated galore times, scope from −2.5% to 4.9%,” helium told Medscape. “This means that the hazard of a COVID-19 corruption successful those utilizing the aesculapian masks could person ranged from anyplace from 2.5% simplification successful hazard to a 4.9% summation successful risk. Readers and argumentation makers tin determine for themselves astir this.”

“There is nary constituent continuing to tally underpowered, poorly designed studies that are designed to corroborate existing biases,” Raina MacIntyre, PhD, prof of planetary biosecurity and caput of the Biosecurity Program astatine the Kirby Institute, successful Sydney, Australia, told Medscape. “The caller survey successful Annals of Internal Medicine is wholly accordant with our uncovering that to forestall infection, you request an N95, and it needs to beryllium worn passim the full shift. A surgical disguise and intermittent usage of N95 are arsenic ineffective. This should not astonishment anyone, fixed a surgical disguise is not designed arsenic respiratory extortion but is designed to forestall splash oregon spray of liquid connected the face. Only a respirator is designed arsenic respiratory extortion done some the seal astir the look and the filter of the look portion to forestall inhalation of microorganism laden aerosols, but you request to deterioration it continually successful a high-risk situation similar a hospital.”

“It makes zero consciousness to bash a randomized proceedings connected thing you tin measurement directly," Kimberly Prather, PhD, an atmospheric chemist, professor, and manager of the NSF Center for Aerosol Impacts connected Chemistry of the Environment astatine the University of California, San Diego, told Medscape. "In fact, galore studies person shown aerosols leaking retired of surgical masks. Surgical masks are designed to artifact ample spray droplets. Aerosols (0.5 to 3 µm), which person been shown to incorporate infectious SARS-CoV-2 virus, question with the aerial flow, and escape.”

“This survey … volition beryllium utilized to warrant policies of supplying healthcare workers, and possibly patients and visitors, too, with inadequate protection,” Trish Greenhalgh, MD, prof of superior attraction wellness sciences astatine the University of Oxford, Oxford, United Kingdom, told Medscape.

“These authors person been pushing backmost against treating COVID arsenic airborne for 3 years,” David Fisman, MD, an epidemiologist and infectious illness specializer astatine the University of Toronto's Dalla Lana School of Public Health, Toronto, Ontario, Canada, told Medscape. “So, you’ll spot these folks brandishing this precise flawed proceedings to warrant continuing the corruption power practices that person been truthful disastrous passim the pandemic.”

The survey was funded by the World Health Organization, the Canadian Institutes of Health Research, and the Juravinski Research Institute. Conly reported receiving grants from the Canadian Institutes for Health Research, Pfizer, and the WHO. Chou was a coauthor with 1 of the authors of the Loeb survey connected a akin subject. He besides disclosed being a methodologist for WHO guidelines connected corruption prevention and power measures for COVID-19. Loeb disclosed outgo for adept grounds connected idiosyncratic protective instrumentality from the authorities of Manitoba and the Peel District School Board. MacIntyre has led a ample assemblage of probe connected masks and respirators successful wellness workers, including 4 randomized objective trials. She is the writer of a book, Dark Winter (NewSouth, 2022), which covers the past and authorities of the controversies astir N95 and masks. Prather reported nary disclosures. Greenhalgh is simply a subordinate of Independent SAGE and an unpaid advisor to the philanthropic money Balvi. Fisman has served arsenic a paid ineligible adept for the Ontario Nurses' Association successful their situation to Directive 5, which restricted entree to N95 masks successful healthcare. He besides served arsenic a paid ineligible adept for the Elementary Teachers' Federation of Ontario successful its efforts to marque schools safer successful Ontario.

Kate Johnson is simply a Montreal-based freelance aesculapian writer who has been penning for much than 30 years astir each areas of medicine.

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