Tag Archives: Respiratory

Scientists try to ‘see’ invisible transmission of coronavirus through respiratory droplets

This is an excerpt from Second Opinion, a weekly roundup of eclectic and under-the-radar health and medical science news emailed to subscribers every Saturday morning. If you haven’t subscribed yet, you can do that by clicking here.


The coronavirus that causes COVID-19 spreads through droplets that we spew as we breathe, talk, cough and sneeze — so tiny that they’re invisible to the naked eye. 

That’s why questions remain about the virus’s transmission and what precautions need to be taken to curb its spread as governments begin to lift restrictions. Will it help if everyone wears a mask? Is keeping everyone two metres apart far enough?

Some researchers aim to learn more about transmission by trying to make invisible sneezes, coughs and breaths more visible. Here’s a closer look at that research and what it might reveal.

How do scientists think COVID-19 is transmitted?

According to the World Health Organization, the disease spreads primarily through tiny droplets expelled when a person infected with SARS-CoV-2 sneezes, coughs, exhales or spits while talking. They can infect another person who:

  • Comes into contact with those droplets through their eyes, nose or mouth (droplet transmission).

  • Touches objects or surfaces on which droplets have landed and then touches their eyes, nose or mouth (contact transmission).

The WHO says it’s important to stay “more than one metre away” from a person who is sick. But the Public Health Agency of Canada recommends staying a distance of at least two metres or two arms’ lengths away, not just from people who are sick but from all people you don’t live with.

Why is 2 metres the recommended distance for preventing transmission?

Scientists in the 19th century showed respiratory droplets from a person’s nose and mouth can carry micro-organisms such as bacteria and viruses.

Then, in 1934, W.F. Wells at the Harvard School of Public Health showed that large droplets (bigger than 0.1 millimetre) tended to fall and settle on the ground within a distance of two metres, while smaller droplets evaporated and the virus particles left behind could remain suspended in the air for a long time.


Wells proposed that could explain how diseases are transmitted.

Since then, respiratory diseases have been divided into those transmitted via droplets (usually from close contact) and those that are airborne and can spread over longer distances, such as measles or tuberculosis. 

Such tiny particles are presumably pushed around by air currents, but can’t move easily due to air resistance. So their actual movements haven’t been well modelled or measured, said Lydia Bourouiba, professor and director of the Fluid Dynamics of Disease Transmission Laboratory at the Massachusetts Institute of Technology. 

“And that’s why the notion of airborne [transmission] is very murky,” said Bourouiba, who is Canadian.

Why don’t experts think the virus is airborne?

A pair of recent studies raised the notion of airborne transmission, but Mark Loeb, a professor at Hamilton’s McMaster University who specializes in infectious disease research, cautions against putting too much stock in them. 

Researchers found traces of RNA from SARS-CoV-2 in washrooms and some high-traffic areas in hospitals in Wuhan, China, and in Nebraska, and suggested it got into those areas through the air, though there was no evidence the particles were still infectious. 


Government guidelines in Canada recommend that people stay at least two metres away from others as part of physical distancing measures to curb the spread of COVID-19. (Gary Moore/CBC)

Loeb said that’s just a “signal” that part of the virus was there. 

“Does it mean that COVID-19 is spreading from person to person through aerosols? I would say definitively not,” Loeb said. 

If the virus were airborne, we’d know by now, said Dr. Allison McGeer, because every health care worker would be infected despite wearing personal protective equipment.

“You and I don’t have to worry walking down the street that we’re going to be breathing the air of somebody who walked down the street five minutes ahead of us who had COVID-19 and didn’t know it,” said McGeer, an infectious disease specialist with Sinai Health in Toronto who is leading a national research team studying how COVID-19 is transmitted. “That we can be confident about.”

Is there evidence the virus could be spread farther than 2 metres?

Some studies, including Bourouiba’s, show that droplets from coughs and sneezes can, in fact, travel much farther than expected. Bourouiba’s high-speed imaging measurements and modelling show smaller respiratory droplets don’t behave like individual droplets but are in a turbulent gas cloud trapping them and carrying them forward within it. The moist environment reduces evaporation, allowing droplets of many sizes to survive much longer and travel much farther than two metres — up to seven or eight metres, in the case of a sneeze

WATCH | Close-up view of the droplets released by a person sneezing

(Credit Lydia Bourouiba/MIT/JAMA Networks)

She said the research “is about revealing what you cannot see with the naked eye.”

A more recent Canadian study used a “cough chamber” to show that if someone coughs without covering their mouth, droplets from the cough are still travelling at a speed of about one kilometre per hour when they hit the two-metre edge of the chamber. Within the chamber, droplets remained suspended for up to three minutes. 

WATCH | The speed and distance travelled by droplets from a cough

Dr. Samira Mubareka, a virologist at Sunnybrook Hospital in Toronto who co-authored the study, said it “gives you a sense of what the possibilities are,” but noted that the researchers, who were studying flu patients, detected very little virus in the droplets.

What does that say about the 2-metre guideline?

Bourouiba says her research points to the potential for exposure beyond two metres from someone who is coughing and sneezing. As she wrote in the journal JAMA Insights in March, that means it’s “vitally important” for health care workers to wear high-grade personal protective equipment in the form of respirators even if they’re farther than two metres away from infected patients.  

However, she does think two metres can be far enough for healthy people in the general public in most environments, since breathing and talking don’t propel droplets and surrounding cloud too far.

Mubareka stands by the two-metre guideline despite the findings of her cough chamber study.

Because despite dramatic images of respiratory droplets being propelled from someone’s nose and mouth, it’s not yet clear how many of them contain virus and how many are infectious.

“And that’s really the key variable — that’s what really determines your risk,” she said. “Those are the kinds of things we haven’t been able to measure.” That may change, she added, with the recent invention of particle samplers designed specifically for viruses.

Loeb of McMaster, notes that a cough chamber and similar laboratory setups are highly artificial settings and controlled environments.

“They’re basically saying what’s theoretically possible,” he said. “I think those are provocative and those are hypothesis- generating, but then they need to be tested in the field.”

Loeb is running such a field test himself — a randomized controlled trial of the use of medical versus N95 masks among health care workers to see if there is a difference in the transmission of COVID-19.

But are coughing and sneezing all we need to worry about?

That’s a question on a lot of people’s minds, given that a growing number of studies have shown asymptomatic and pre-symptomatic transmission is possible, especially among those who live with an infected person. 

Even though researchers aren’t sure exactly how people without symptoms transmit the disease, the new evidence has prompted both U.S. and Canadian officials to suggest apparently healthy people wear masks in public to protect others — “because it prevents you from breathing or speaking moistly on them,” Prime Minister Justin Trudeau famously explained.

“People generate particles when they’re talking, singing, breathing — so you don’t have to necessarily be coughing,” Mubareka said. “It’s just that maybe the dispersion is a little bit more limited.” 

WATCH | The droplets produced when someone speaks with, and without, a mask

This video, from a study published in April 2020 the New England Journal of Medicine by researchers at the U.S. National Institutes of Health, uses laser light scattering to show droplets produced when someone speaks. 0:42 

A recent brief video and report by U.S. National Institutes of Health researchers used lasers to show that droplets projected less than 10 centimetres when someone says the phrase “Stay healthy.” It found the louder someone spoke, the more droplets were emitted.

But they were dramatically reduced if a damp washcloth — a stand-in for a mask — was placed over the speaker’s mouth.

So what about using masks to curb the spread of COVID-19?

Studies have already provided evidence that the rate at which sick people shed the virus into their surroundings is reduced when they wear a mask. 

Other studies, such as a 2009 paper in Journal of the Royal Society Interface, use imaging to show how wearing a mask while coughing reduces the jet of air that’s normally directed forward and down. A surgical mask “effectively blocks the forward momentum of the cough jet and its aerosol content,” the study found. Some does leak out the sides, top and bottom, but without much momentum.


A 2009 study by researchers in the U.S. and Singapore uses schlieren imaging to show airflow from a person’s mouth a) without a mask b) with a medical mask and c) with an N95 mask. (Gary S. Settles/Penn State University/Journal of the Royal Society Interface)

The World Health Organization recommends that people wear masks if they are coughing and sneezing or if they are caring for someone who is sick.

It notes that studies haven’t been conducted yet on whether or not transmission is reduced when healthy people wear masks in public, but it encourages countries to look into that. 

Many governments haven’t waited. Los Angeles, Italy and Austria are among the places that have begun requiring customers to wear masks while shopping


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Hong Kong to add mystery respiratory illness to reportable diseases

Hong Kong’s health chief said Tuesday that a respiratory illness whose cause remains unknown will be added to an official list of diseases that medical practitioners are required to report to the government.

The disease — an unidentified form of viral pneumonia — has sent 59 people to the hospital in the mainland Chinese city of Wuhan, in central Hubei province. As of Sunday, seven were in critical condition, while the rest were stable. Municipal authorities have ruled out SARS, the severe acute respiratory syndrome that killed 700 people in 2002 and 2003.

In Hong Kong, a total of 15 patients were being treated Sunday for symptoms including fever and respiratory infection after recent visits to Wuhan. It is not clear whether they have the same illness as the Wuhan patients.

Speaking at a news conference, the health chief, Sophia Chan, said the “severe respiratory disease associated with a novel infectious agent” will be added to a list of reportable infectious diseases in Hong Kong’s Prevention and Control of Disease Ordinance.

The regulation enables the government to take stronger measures against the spread of certain diseases, such as tuberculosis and chicken pox. Actions under the ordinance could include enforcing quarantines or limiting the movement of people who are suspected to have infections.

“Under the amendment, medical practitioners will have to report suspected cases as well as carry out appropriate investigations and follow-ups to the Center for Health Protection under the Department of Health,” Chan said.

The U.S. Consulate General in Wuhan issued a health alert Tuesday for the pneumonia outbreak, warning travellers to Wuhan to avoid animals, as well as animal markets and products.

Dr. Gauden Galea, WHO Representative to China, said public health officials in China “remain focused on continued contact tracing, conducting environmental assessments at the wholesale market, and investigations to identify the pathogen causing the outbreak.”

WHO is closely monitoring the event and communicating with counterparts in China, Galea added in a emailed statement.

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Authorities say mysterious respiratory illness in China not SARS

The mysterious respiratory illness that has infected dozens of people in a central Chinese city is not SARS, local authorities said Sunday.

The 2002-2003 epidemic of Severe Acute Respiratory Syndrome (SARS) started in southern China and killed more than 700 people in mainland China, Hong Kong and elsewhere. SARS claimed 44 lives in Canada, with people working in healthcare particularly vulnerable. 

Fears of a SARS recurrence arose this month after a slate of patients were hospitalized with an unexplained viral pneumonia in Wuhan, the capital of Hubei province.

As of Sunday, 59 people were diagnosed with the condition and have been isolated while they receive treatment, according to the Wuhan Municipal Health Commission. Seven were in critical condition, while the rest were stable.

The commission said in a statement that initial investigations have ruled out SARS, as well as Middle East respiratory syndrome, influenza, bird flu and adenovirus.

The commission previously said the condition’s most common symptom was fever, with shortness of breath and lung infections appearing in a “small number” of cases. There were no clear indications of human-to-human transmission.

Several patients were working at the South China Seafood City food market in sprawling Wuhan’s suburbs. The commission said the market would be suspended and investigated.

15 infected in Hong Kong

Hong Kong’s Hospital Authority said Sunday that a total of 15 patients in Hong Kong were being treated for symptoms including fever and respiratory infection after recent visits to Wuhan.

Hospitals and doctors have been directed to report cases of fever in anyone who has travelled to Wuhan in the past 14 days, Hong Kong’s health chief Sophia Chan said Sunday.

The hospital authority said it has activated a “serious response” level to curb spread of the infection. Chan warned Hong Kong residents against visiting wet markets and eating wild game in mainland China.

The World Health Organization said it was closely monitoring the situation and maintaining contact with Chinese authorities. No travel or trade restrictions are necessary at this time, the WHO said.

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China investigating outbreak of respiratory illness

Chinese experts are investigating an outbreak of respiratory illness in the central city of Wuhan that some have likened to the 2002-2003 SARS epidemic.

The city’s health commission said in a statement Tuesday that 27 people had fallen ill with a strain of viral pneumonia, seven of whom were in serious condition.

It said most had visited a seafood market in the sprawling city, apparently pointing to a common origin of the outbreak.

Unverified information online said the illnesses were caused by severe acute respiratory syndrome, which emerged from southern China and killed more than 700 people in several countries and regions.

SARS was brought under control through quarantines and other extreme measures, but not before causing a virtual shutdown to travel in China and the region and taking a severe toll on the economy.

However, the health commission said the cause of the outbreak was still unclear and called on citizens not to panic.

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Ontario teen was on life-support after respiratory illness linked to vaping

An Ontario teenager was put on life-support after using a vaping device in what public health officials say is the first reported case of illness linked to the practice in Canada.

Officials with the Middlesex-London Health Unit were alerted by a local doctor after the high school student fell ill and was sent to hospital.

“The individual was using e-cigarettes at least daily,” said Dr. Chris Mackie, the region’s medical officer of health.

“We have information about the brand used.”

That information is not being released but has been passed to Canada’s chief medical officer of health who will be gathering systematic data to determine if one vaping device is more potent than another.

“We’re not releasing information about the brand information because that would imply that this is something coming from one brand, when clearly looking at the international evidence, that’s not the case,” Mackie said.

Mackie said the teen has been released from hospital and is doing well.

It’s important that people understand vaping does create health risks.– Dr. Chris Mackie

“There are some who claim that vaping is not a risk in Canada,” he said. “That is not the case. It’s important that people understand vaping does create health risks.”

There have been hundreds of such cases in the United States, but this is believed to be the first case of severe pulmonary illness linked to vaping in Canada. 

“We know very little about the long-term health effects associated with e-cigarettes, but our findings so far are enough to convince us of the need to advise the public,” Mackie said.

Mackie did caution that it’s impossible to 100 per cent confirm the youth’s illness was caused by vaping, but said there was no other evidence to suggest it was caused by something else. 


Dr. Chris Mackie is the Middlesex-London Health Unit’s medical officer of health. He said the use of vaping products is escalating. (Andrew Lupton/CBC)

“There was no other cause — no infectious cause,” he said. “The only issue identified is that the individual vaped e-cigarettes.

The health unit says it will not disclose the age, gender or hometown of the patient, claiming confidentiality. 

The news comes on the same day as the Ontario health minister ordered public hospitals to report vaping-related cases of severe pulmonary disease. 

Use ‘escalating’ among youth

It also follows a directive from Health Canada to health-care professionals, telling them to ask patients about their vaping use and if they have any trouble breathing or shortness of breath. 

“The use of these products is escalating at a rate we’ve never seen,” said Linda Stobo, the Middlesex-London Health Unit’s manager of chronic disease prevention and tobacco control team. “Our enforcement officers have seen an exponential increase in the number of students who vape, particularly high school-aged youth, which is a major concern for us.” 

Stobo said the e-cigarettes are marketed in a way that targets a young demographic including:

  • Sleek designs with options to customize the look, including different colours.
  • Hundreds of flavours of e-juice, including candy, designed to attract youth. 
  • Marketing that uses words such as “bold,” “stylish,” “attractive” and “try it.”
  • Some vaping devices can be charged using a computer or cellphone charger, making them enticing to a generation already enamoured with technology. 

Stobo also said she’s worried about the high concentrations of nicotine found in some of the products. She also said local schools are reporting students vaping in washrooms, classrooms and even buses.

Liberal Leader Justin Trudeau made a brief stop in Salisbury NB on Wednesday 0:53

Selling vaping products to those under 18 isn’t allowed in Canada, but Health Canada wants to strengthen rules to limit the visibility of vaping ads to young people. 

Some proponents of vaping insist it can be an effective way to prevent people from smoking tobacco, or a way to help smokers quit cigarettes. 

Mackie, however, said it can often work the other way. That someone not interested in smoking may start with vaping then transfer over to cigarettes because they’re cheaper.  

“If you start people on smoking e-juice … then when they run out of money the smoking behaviour starts up,” he said. 

In the United States, there have been hundreds of cases of respiratory illnesses linked to vaping and at least seven deaths. Many of those deaths were linked to vaping cannabis. Mackie wouldn’t say whether cannabis was a factor in the London, Ont., case. 

“The information we have … is that there’s no particular brand that has been implicated, and there’s no particular link with cannabis or not,” he said. “There are cases where cannabis has been involved and cases where it hasn’t been. 

India on Wednesday moved to ban the production, import and sale of electronic cigarettes.

However, the London-Middlesex case is believed to be the first reported in Canada. 

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Ontario youth’s respiratory illness linked to vaping — believed to be first in Canada

A youth in Ontario could be Canada’s first patient with a serious lung disease linked to vaping. 

Later this afternoon, the Middlesex-London Health Unit is expected to give more details about the patient who has been diagnosed with a “severe respiratory illness” that’s been linked to the individual’s use of vaping products. 

The health unit says it will not disclose the age, gender or hometown of the patient, claiming confidentiality. 

The news comes on the same day as the Ontario health minister ordered public hospitals to report vaping-related cases of severe pulmonary disease. 

It also follows a directive from Health Canada to health-care professionals, telling them to ask patients about their vaping use and if they have any trouble breathing or shortness of breath. 

Selling vaping products to those under 18 isn’t allowed in Canada, but Health Canada wants to strengthen rules to limit the visibility of vaping ads to young people. 

In the United States, there have been hundreds of cases of respiratory illnesses linked to vaping and at least seven deaths. However, the London-Middlesex case is believed to be the first reported in Canada. 

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Illinois resident dies after respiratory illness tied to vaping

llinois health officials have reported what could be the first death in the United States that has been associated with vaping.

The Illinois Department of Public Health says an adult who recently vaped died after being hospitalized with “severe respiratory illness.” The agency didn’t give any other information about the patient, including a name or where the person lived.
 
Melaney Arnold, an agency spokeswoman, says the death is the first in the state that could be linked to vaping. The release also says the number of people who have experienced respiratory illness after vaping doubled to 22 in the past week.  

In a media briefing on Friday, officials with the U.S. Centers for Disease Control and Prevention said 193 cases of severe lung illness have been reported that may be tied to vaping. People have been hospitalized in 22 states.

State health officials are asking doctors and hospitals to tell them about any possible vaping-related lung disease cases they encounter.

Health Canada officials said they haven’t received reports of pulmonary disease related to vaping. Canadian doctors say they’re on the lookout.

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Mariah Carey Cancels First Shows of Christmas Concert Due to Respiratory Infection

Mariah Carey will have to take some time off from singing on stage.

The “All I Want for Christmas Is You” songstress took to Twitter on Wednesday to inform fans that unfortunately, due to a respiratory infection, she has been forced to cancel a handful of her upcoming Christmas shows.

“Just in time for the holiday gift-giving season, it seems I’ve received a present of my own; a lovely upper respiratory infection after last week’s flu,” Carey writes to her Lambs. “You know there is nothing I love more than celebrating the holidays with my festive Christmas show, but I have to take my doctor’s orders and rest until he says I can sing on stage.”

Mimi continues, adding the first several shows of her holiday tour will have to be canceled, but that she hopes she’ll be able to see her fans soon.

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