Should we all be wearing masks to slow COVID-19? Some experts change their minds


Dr. Theresa Tam, Canada’s chief public health officer, put it mildly when she tweeted Wednesday night, “There is a lot of talk about the use of face masks.”

In recent destabilizing weeks, dramatic efforts to stop the spread of COVID-19 have sparked a wave of new, sometimes contradictory, directives that seem to be evolving as rapidly as the virus itself. But even by pandemic standards, the conflicting opinions on whether we should all cover our noses and mouths in public make our heads spin.

Infection prevention and control doctor at Public Health Ontario, Dr. Gary Garber, said on Friday that the agency, which provides scientific and technical expertise to the government, “is carrying out a scientific review of the problem”, the latest indication that this question is really a moving target. Currently, the Ontario public health agency does not recommend wearing the mask unless you have COVID-19 or are caring for someone with the virus.

“There is a debate among all the experts,” said Margaret Sietsema, respiratory protection expert and assistant professor at the University of Illinois at Chicago, who is on the “no” side of the mask for everyone discussion. “Who knows what’s going on? “

To be clear, the question that a growing number of officials are currently probing – as of Friday, this list included the United States Centers for Disease Control, Public Health Ontario, and a World Health Organization advisory committee – is not whether the public should start putting on medical masks.

As personal protective equipment (PPE) is scarce in many countries, including Canada, there is a broad and powerful consensus among officials on the need to reserve medical grade masks – including surgical masks and good N95 respirators fitted used in hospitals – for health. – caregivers on the front line of the pandemic.

Unlike N95 masks, which contain a filter to protect the user, the growing movement # masks4all sees cloth masks as a means of protecting everyone – a barrier, even an imperfect one, to catch infectious droplets from sneezing, cough and exhalation. This position is gaining momentum with new evidence on COVID-19 that suggests the virus may travel further in the air than previously thought.

However, those on the other side of the debate argue that there is no evidence that cloth masks catch enough infectious droplets to be worth the risk of encouraging universal mask use. These risks include touching our face more often to adjust masks and giving a false sense of security that could cause wearers to be less vigilant about physical distance and hand washing – proven ways to stop the spread. COVID-19.

Thursday marked a break between Canadian and American officials on this issue, at least for the time being. After initially declaring that wearing a universal mask is not necessary, US President Donald Trump has said he plans to issue new guidelines urging all Americans to put on their faces in public, based on a recommendation to come from the Centers for Disease Control.

Then, Friday night, during his White House briefing, Trump said that the Centers for Disease Control recommended that Americans voluntarily use “non-medical cloth” masks, the New York Times reported.

” You can do it. You don’t have to. I choose not to, ”said Trump. “This is only a recommendation. “

In contrast, the message from Ottawa officials to Canadians is to wear homemade masks at their discretion – and with caution.

On Tuesday, Health Canada issued a notice on homemade masks, warning that due to the loose fit and the materials used, “these types of masks may not be effective in blocking viral particles.”

When Tam solved the problem on Twitter On Wednesday, she recognized that a homemade mask can help fight the cough label – similar to coughing in your sleeve. But she included several caveats, including the risk of contamination from outside masks and the fact that the virus can enter the eyes. “Non-medical masks alone will not prevent the spread of # COVID19,” she wrote, urging the public to “systematically and strictly” adhere to frequent hand washing and physical removal.

Tam and Federal Minister of Health Patty Hajdu reiterated this message at press briefings in Ottawa this week, repeatedly emphasizing the need to keep medical masks for healthcare workers.

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In an email Thursday, a spokesperson for the Ontario Ministry of Health said, “There is no real evidence of the impact of homemade masks on preventing spread or protecting the community.” of oneself. Although masks can reduce the frequency of someone touching their nose or mouth, this potential positive effect is also linked to good hand hygiene. “

Public health recommendations in Ontario are consistent with current WHO recommendations. But that advice can change too: infectious disease expert David Heymann, who chairs a group of WHO advisers, told the BBC on Wednesday that the group was considering further research on COVID-19 from the Massachusetts Institute of Technology, which suggests that coughing can travel up to six meters and sneezing up to eight meters – four times public health officials of the berth recommend adequate physical distance.

“WHO is opening its discussion again by examining the new evidence to see if there should be a change in the way it recommends the use of masks,” Heymann told the BBC.

In an interview earlier this week, Garber of the Ontario Public Health Agency said that it is “difficult to attribute” evidence to the idea of ​​enticing everyone to wear masks help curb the spread of COVID-19, and cautioned against taking advantage of success too much. stories from some Asian countries, where the mask is more common.

“Why in China did they put such a tight lock on Wuhan?” Garber said. “If masking was so effective, why didn’t they just apply it? “

Garber noted in a email on Friday a comment released this week by the U.S. Center for Infectious Disease Research and Policy, who, he said, found “no evidence to support the plan” to wear the universal mask. Co-written by Sietsema, the commentary, which is based on a review of the literature on the subject, strongly argues against masks for all, due to the lack of scientific data showing that fabric – or surgical – masks contain enough infectious droplets to make them worthwhile.

“Leaving aside the fact that they are ineffective, telling the public to wear surgical clothing or masks could be interpreted by some to mean that people are sure to end the isolation at home,” said the commentary. “It is too late now for anything other than to stop as many people-to-people interactions as possible. “

But for all the experts who plead against universal masking, there is a study which seems to argue in favor of the other side, although none is final or necessarily applicable in countries like Canada, where medical masks are rare .

Friday, Benjamin Cowling, professor of public health at the University of Hong Kong, tweeted: “A new study has just come out, effective masks for source control against influenza and seasonal coronaviruses. In the article published in Nature, Cowling and his co-authors write: “Our results indicate that surgical masks could prevent the transmission of human coronaviruses and influenza viruses by symptomatic individuals.”

However, for some experts, the lack of scientific data on the effectiveness of cloth masks is not a reason to abandon the strategy. Michael Garron Hospital in Toronto recently challenged sewing enthusiasts in eastern Canada to make 1,000 cloth masks for distribution to approved visitors and inpatients upon discharge.

In a post on the hospital’s website, Dr. Jeff Powis, medical director of infection prevention and control, said, “We want to see everyone in the east wear a cloth mask when they must be within six feet of other people, especially vulnerable populations and the elderly. ”

In response to questions from the Star about this initiative, Powis said in an email: “Unfortunately, there is no time for a randomized controlled trial to assess the effectiveness of public masking, and at this critical stage of the pandemic, a lack of definitive evidence will lead to inaction. “

Powis added that cloth masks “do not replace social distancing or hand washing; it is added to these interventions. “

With files from Tonda MacCharles


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