Tom Blackwell
POSTMEDIA
Looser-fitting surgical and cloth masks provide minimal protection against those particles. As well as advocating for tighter-fitting N95 masks or their equivalent, aerosol proponents call for better building ventilation and stress the added infection risk of indoor activity.
As evidence, they cite outbreaks that seem hard to explain with the droplet theory, like the scores of passengers on the Diamond Princess cruise ship infected while mostly holed up in their cabins, people in quarantine hotels who contracted COVID despite having no direct contact with the infected person next door, and choir practices where multiple, well-separated vocalists were infected by a singing index patient.
They also point to the discovery of virus in hospital duct systems, in the air of patient rooms and even a COVID case’s car. Experiments have managed to infect animals with the virus through airborne transmission.
The proof may not be definitive but it actually surpasses the science backing up the droplet idea and is more than enough reason to take action, asserts Dr. Raymond Tellier, a McGill University medical microbiologist.
“If you smell smoke and the fire alarm goes off, do you wait to see the flames before getting out?”
In fact, after some vocal protests, both the WHO and CDC have revised their online messaging about COVID-19 transmission, acknowledging a significant role for aerosols.
“I think the scientific debate is getting to the end,” said Tellier.
Or maybe not. Other experts argue there is still much uncertainty .
Yes, airborne spread occurs in some circumstances, they concede, but it’s unclear how much of a role it plays and what that means for practical matters like deciding what type of protective equipment is best for health-care workers and others.
Infectious disease specialists say their experience in the clinic is that most patients were infected by close contact.
They also point to a sort of surrogate form of evidence: the effectiveness of different types of mask.
In the pandemic’s first wave, limited testing that disproportionately targeted health-care workers made it difficult to assess their relative risk, said McGeer. But a Public Health Ontario study found that by last September, as testing broadened, those staff were no more likely to catch the virus than the general public. Yet the province’s protocol was for workers to wear surgical masks and face shields, donning N95s only for “aerosol-generating” procedures like inserting breathing tubes, or if deemed necessary by workers’ own personal risk assessment.
Then there is the huge “natural experiment” set in motion by Germany and Austria earlier this year. Both nations mandated that citizens wear the equivalent of N95 in stores, public transit and other enclosed spaces — the kind of practice that airborne-spread proponents urge. The measure failed, however, to prevent a raging third wave of coronavirus that stretched the countries’ hospitals to the limit.
© Provided by National Post Should we all be wearing N95 masks
Dr. John Conly is no slouch as an infectious disease specialist.
He’s an international leader in fighting antibiotic resistance, was inducted into the Order of Canada and now chairs an expert committee that advises the World Health Organization on COVID-19 infection control.
But when the University of Calgary professor downplayed the role of airborne transmission of the virus during a panel discussion last month — then was the subject of an unflattering news story — the response was harsh.
Social media attacks compared Conly and like-thinking colleagues to Auschwitz doctor Josef Mengele , called him stupid and a quack, and suggested he was responsible for “millions” of deaths.
Dr. John Conly is no slouch as an infectious disease specialist.
He’s an international leader in fighting antibiotic resistance, was inducted into the Order of Canada and now chairs an expert committee that advises the World Health Organization on COVID-19 infection control.
But when the University of Calgary professor downplayed the role of airborne transmission of the virus during a panel discussion last month — then was the subject of an unflattering news story — the response was harsh.
Social media attacks compared Conly and like-thinking colleagues to Auschwitz doctor Josef Mengele , called him stupid and a quack, and suggested he was responsible for “millions” of deaths.
Sgt Johanie Maheu / Rideau Hall Dr. John Conly received the Order of Canada during a ceremony at Rideau Hall, on May 8, 2019.
The Calgary scientist’s online skewering, however, was just one recent salvo in a scientific row that has turned surprisingly combative.
The dispute revolves around what once might have seemed like an esoteric question: How exactly does SARS-CoV-2 spread from person to person. The conventional wisdom points to close contact and heavy “droplets” that fall quickly to the ground, but a growing and vocal alternative school of thought asserts that it is largely via tiny aerosol particles that can stay airborne and travel longer distances.
Who’s right has important implications for the ways we combat COVID-19 — at least until vaccination is widespread. The disagreement, in the meantime, is heated.
Two other infectious disease experts contacted for this story declined to be interviewed on the record. One who had a paper on the topic published last year called it a “dicey, dicey” issue that had already brought him much online abuse. Another said he had also been the target of online harassment.
“It’s very volatile, the topic,” the researcher said. “There’s a Twitter mob that attacks any time anybody suggests the transmission might not be 100 per cent aerosol. It’s a very loud voice, unfortunately.”
There’s even been hate for a Canadian-run clinical trial trying to resolve one of the key issues in the debate — whether health-care workers should wear more protective N95 masks or regular surgical ones.
An Australian emergency physician active on Twitter castigated the study as being so unethical it was “full Nazi.” Other health professionals have urged funding agencies to shut the trial down and have the lead investigator “apologize” to subjects.
Ontario’s nurses’ union advised its members against participating.
“I don’t understand why (aerosol vs. droplet) is such a touch point of controversy,” said Dr. Allison McGeer of Toronto’s Mount Sinai hospital, one of the country’s leading experts on respiratory viruses. “You would like us academics to achieve consensus in the middle of chaos, but this is one of those areas where we can’t do that.”
The feverishness of the dispute seems at least partly a symptom of both the verbal knife-fighting that social-media often fosters and a pandemic whose science — and passionate scientific disagreements — are unspooling under unprecedented public scrutiny.
Added to the mix are health-care unions that have forcefully pushed for more widespread use of N95 masks as a defence against what they’re convinced is airborne spread.
The Calgary scientist’s online skewering, however, was just one recent salvo in a scientific row that has turned surprisingly combative.
The dispute revolves around what once might have seemed like an esoteric question: How exactly does SARS-CoV-2 spread from person to person. The conventional wisdom points to close contact and heavy “droplets” that fall quickly to the ground, but a growing and vocal alternative school of thought asserts that it is largely via tiny aerosol particles that can stay airborne and travel longer distances.
Who’s right has important implications for the ways we combat COVID-19 — at least until vaccination is widespread. The disagreement, in the meantime, is heated.
Two other infectious disease experts contacted for this story declined to be interviewed on the record. One who had a paper on the topic published last year called it a “dicey, dicey” issue that had already brought him much online abuse. Another said he had also been the target of online harassment.
“It’s very volatile, the topic,” the researcher said. “There’s a Twitter mob that attacks any time anybody suggests the transmission might not be 100 per cent aerosol. It’s a very loud voice, unfortunately.”
There’s even been hate for a Canadian-run clinical trial trying to resolve one of the key issues in the debate — whether health-care workers should wear more protective N95 masks or regular surgical ones.
An Australian emergency physician active on Twitter castigated the study as being so unethical it was “full Nazi.” Other health professionals have urged funding agencies to shut the trial down and have the lead investigator “apologize” to subjects.
Ontario’s nurses’ union advised its members against participating.
“I don’t understand why (aerosol vs. droplet) is such a touch point of controversy,” said Dr. Allison McGeer of Toronto’s Mount Sinai hospital, one of the country’s leading experts on respiratory viruses. “You would like us academics to achieve consensus in the middle of chaos, but this is one of those areas where we can’t do that.”
The feverishness of the dispute seems at least partly a symptom of both the verbal knife-fighting that social-media often fosters and a pandemic whose science — and passionate scientific disagreements — are unspooling under unprecedented public scrutiny.
Added to the mix are health-care unions that have forcefully pushed for more widespread use of N95 masks as a defence against what they’re convinced is airborne spread.
© Blair Gable Some health-care workers say they need better access to N95 masks.
The Ontario Nurses Association was even scheduled to be in court Wednesday over the issue, asking a judge to order the province’s chief medical officer of health to declare that the coronavirus is primarily transmitted by aerosol.
Linsey Marr, the Virginia Tech engineering professor who is at the forefront of the airborne-transmission movement, sees another reason for the rancour. The experts most attached to the close-contact/droplet theory of spread tend to be infectious disease doctors long steeped in the droplet theory, she said.
“There is a paradigm shift going on here where, because of cognitive bias in the way people were trained, it’s really hard for them to see the evidence for what it is,” Marr said. “Which is overwhelming now that COVID-19 is being transmitted by aerosols.”
Settled or not, the question in some ways comes down to tiny fractions of millimetres.
The long-held view is that respiratory viruses such as COVID are spread primarily through “droplets” expelled by infected people, globules of moisture often visible with the naked eye. Relatively heavy, they sink to the ground within a metre or so. Someone contracts the bug when a droplet lands on their eyes, nose or mouth, or they touch those facial openings with droplet-contaminated hands.
Until recently, major public health bodies like the WHO, Health Canada and U.S. Centers for Disease Control, have attributed the pandemic’s spread almost entirely to that mode of transmission.
But many scientists — led by engineers and other researchers who study air flow and aerosolization — argue COVID-19 has been spread to a great degree by much smaller, aerosol particles that, like cigarette smoke, can float in the air for hours before someone inhales them.
The Ontario Nurses Association was even scheduled to be in court Wednesday over the issue, asking a judge to order the province’s chief medical officer of health to declare that the coronavirus is primarily transmitted by aerosol.
Linsey Marr, the Virginia Tech engineering professor who is at the forefront of the airborne-transmission movement, sees another reason for the rancour. The experts most attached to the close-contact/droplet theory of spread tend to be infectious disease doctors long steeped in the droplet theory, she said.
“There is a paradigm shift going on here where, because of cognitive bias in the way people were trained, it’s really hard for them to see the evidence for what it is,” Marr said. “Which is overwhelming now that COVID-19 is being transmitted by aerosols.”
Settled or not, the question in some ways comes down to tiny fractions of millimetres.
The long-held view is that respiratory viruses such as COVID are spread primarily through “droplets” expelled by infected people, globules of moisture often visible with the naked eye. Relatively heavy, they sink to the ground within a metre or so. Someone contracts the bug when a droplet lands on their eyes, nose or mouth, or they touch those facial openings with droplet-contaminated hands.
Until recently, major public health bodies like the WHO, Health Canada and U.S. Centers for Disease Control, have attributed the pandemic’s spread almost entirely to that mode of transmission.
But many scientists — led by engineers and other researchers who study air flow and aerosolization — argue COVID-19 has been spread to a great degree by much smaller, aerosol particles that, like cigarette smoke, can float in the air for hours before someone inhales them.
Looser-fitting surgical and cloth masks provide minimal protection against those particles. As well as advocating for tighter-fitting N95 masks or their equivalent, aerosol proponents call for better building ventilation and stress the added infection risk of indoor activity.
As evidence, they cite outbreaks that seem hard to explain with the droplet theory, like the scores of passengers on the Diamond Princess cruise ship infected while mostly holed up in their cabins, people in quarantine hotels who contracted COVID despite having no direct contact with the infected person next door, and choir practices where multiple, well-separated vocalists were infected by a singing index patient.
They also point to the discovery of virus in hospital duct systems, in the air of patient rooms and even a COVID case’s car. Experiments have managed to infect animals with the virus through airborne transmission.
The proof may not be definitive but it actually surpasses the science backing up the droplet idea and is more than enough reason to take action, asserts Dr. Raymond Tellier, a McGill University medical microbiologist.
“If you smell smoke and the fire alarm goes off, do you wait to see the flames before getting out?”
In fact, after some vocal protests, both the WHO and CDC have revised their online messaging about COVID-19 transmission, acknowledging a significant role for aerosols.
“I think the scientific debate is getting to the end,” said Tellier.
Or maybe not. Other experts argue there is still much uncertainty .
Yes, airborne spread occurs in some circumstances, they concede, but it’s unclear how much of a role it plays and what that means for practical matters like deciding what type of protective equipment is best for health-care workers and others.
Infectious disease specialists say their experience in the clinic is that most patients were infected by close contact.
They also point to a sort of surrogate form of evidence: the effectiveness of different types of mask.
In the pandemic’s first wave, limited testing that disproportionately targeted health-care workers made it difficult to assess their relative risk, said McGeer. But a Public Health Ontario study found that by last September, as testing broadened, those staff were no more likely to catch the virus than the general public. Yet the province’s protocol was for workers to wear surgical masks and face shields, donning N95s only for “aerosol-generating” procedures like inserting breathing tubes, or if deemed necessary by workers’ own personal risk assessment.
Then there is the huge “natural experiment” set in motion by Germany and Austria earlier this year. Both nations mandated that citizens wear the equivalent of N95 in stores, public transit and other enclosed spaces — the kind of practice that airborne-spread proponents urge. The measure failed, however, to prevent a raging third wave of coronavirus that stretched the countries’ hospitals to the limit.
© Bing Guan A North Dakota Army National Guard deputy state surgeon wears a UVEX face shield and N95 protective mask as he watches a drive-thru COVID-19 testing site in October 2020.
A Canadian clinical trial is trying to empirically measure the face coverings’ relative value against SARS-CoV-2, and is facing repeated push-back. The volunteers randomly assigned to the surgical-mask arm of the study are following current protocol and can put on N95s when they feel it necessary; those in the other arm wear N95s all the time. Yet opponents argue the trial puts nurses at undue risk.
“We don’t need a study. In the midst of a pandemic, this is unethical,” said Vicki McKenna, president of the ONA. “On humans, really? It just leaves a bad taste and optically it’s really wrong.”
Conly, meanwhile, said he’s alright with a vigorous exchange of scientific views, as he said happened in the pre-social-media age.
But on the internet during the pandemic, he maintains, lines are constantly being crossed.
In the online seminar, Conly — a respected clinician and scientist, whose role as chair of the WHO’s infection control and prevention research working group is unpaid — suggested additional research is needed on airborne transmission. He responded to a call for more widespread N95 use in part by suggesting the tight-fitting masks had drawbacks, including causing acne. A later CBC story portrayed him as a powerful, out-of-touch force preventing the WHO from seeing the light on aerosols.
Then came the online barrage.
Critics urged the university to retire Conly and others to file disciplinary complaints with Alberta’s medical regulator. One tweet said he “could be responsible for millions of deaths & suffering because of is (sic) arrogance in not looking at the science of airborne trans.”
Another referred to a paper he and others wrote that proposed a pyramid of different levels of evidence for determining how COVID is spread, where the top would be deliberate, experimental infection of subjects. They didn’t actually advocate such research. But the Twitter user referred to it as “Mengele’s pyramid,” after the doctor who conducted cruel experiments on children and other prisoners at the Auschwitz concentration camp.
The post was re-tweeted by David Fisman, a University of Toronto epidemiologist, who referred to Conly and his co-authors — two of whom are women — as “a group of sulky men on the wrong side of an argument.”
Conly says he has a “strong constitution” but began taking the insults to heart when his children said they had to defend him to friends who’d seen the social media assaults.
“It’s hurtful, there’s no two ways about it,” he said. “I’m seeing too much of this: personal attack, denigrating individuals, not just in academia, but in public health, too…. It just seems to me that we’ve lost our way.”
A Canadian clinical trial is trying to empirically measure the face coverings’ relative value against SARS-CoV-2, and is facing repeated push-back. The volunteers randomly assigned to the surgical-mask arm of the study are following current protocol and can put on N95s when they feel it necessary; those in the other arm wear N95s all the time. Yet opponents argue the trial puts nurses at undue risk.
“We don’t need a study. In the midst of a pandemic, this is unethical,” said Vicki McKenna, president of the ONA. “On humans, really? It just leaves a bad taste and optically it’s really wrong.”
Conly, meanwhile, said he’s alright with a vigorous exchange of scientific views, as he said happened in the pre-social-media age.
But on the internet during the pandemic, he maintains, lines are constantly being crossed.
In the online seminar, Conly — a respected clinician and scientist, whose role as chair of the WHO’s infection control and prevention research working group is unpaid — suggested additional research is needed on airborne transmission. He responded to a call for more widespread N95 use in part by suggesting the tight-fitting masks had drawbacks, including causing acne. A later CBC story portrayed him as a powerful, out-of-touch force preventing the WHO from seeing the light on aerosols.
Then came the online barrage.
Critics urged the university to retire Conly and others to file disciplinary complaints with Alberta’s medical regulator. One tweet said he “could be responsible for millions of deaths & suffering because of is (sic) arrogance in not looking at the science of airborne trans.”
Another referred to a paper he and others wrote that proposed a pyramid of different levels of evidence for determining how COVID is spread, where the top would be deliberate, experimental infection of subjects. They didn’t actually advocate such research. But the Twitter user referred to it as “Mengele’s pyramid,” after the doctor who conducted cruel experiments on children and other prisoners at the Auschwitz concentration camp.
The post was re-tweeted by David Fisman, a University of Toronto epidemiologist, who referred to Conly and his co-authors — two of whom are women — as “a group of sulky men on the wrong side of an argument.”
Conly says he has a “strong constitution” but began taking the insults to heart when his children said they had to defend him to friends who’d seen the social media assaults.
“It’s hurtful, there’s no two ways about it,” he said. “I’m seeing too much of this: personal attack, denigrating individuals, not just in academia, but in public health, too…. It just seems to me that we’ve lost our way.”
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