When 61 members of a choir gathered for a practice in Mount Vernon, Washington on March 10 – one with symptoms of COVID-19 – the group had no way of knowing how much worse it could get.
The two and a half hour practice was an ideal scenario for the virus to spread: the choir members sat close to each other, sang together, shared snacks and stacked chairs when finished.
Two weeks later, 53 of the 61 choir members present had confirmed or probable COVID-19 cases. Three of these people were hospitalized. Two died.
Was it singing, close contact, touching surfaces or sharing food that caused the epidemic? Researchers don’t know which factors mattered most.
But one thing is common between this epidemic and others studied so far: spending a long time together indoors seems to help fuel the spread of COVID-19
Look: Are you more immune to COVID-19 indoors or outdoors?
“There is mounting evidence that it can spread through the air,” said Linsey Marr, aerosol virus specialist at Virginia Tech.
“Large epidemics always involve overcrowded places, sometimes poorly ventilated, other times, we don’t know. “
As Canada’s provinces slowly reopen, experts say emerging research offers lessons on how to do it safely – and this suggests that enclosed and closed spaces may pose the greatest risk.
Where do epidemics occur?
Choral practice is the subject of new research American Centers for Disease Control and Prevention it shows how a close gathering can have devastating consequences.
The epidemic is known as ” superspreader event“, Where a highly infectious person can spread the disease to many other people.
Two other recent CDC reports also revealed that the virus could spread more easily in an indoor environment with poor ventilation over an extended period of time.
We watched an epidemic in a call center in South Korea. The report found that 94 of the 97 confirmed cases of COVID-19 in an office building were all people who worked on the same floor.
Another document from researchers in China studied a restaurant in Guangzhou and found an infected individual without symptoms was apparently able to spread the virus to nine others.
The direction in which the air conditioning system was perhaps blowing helped transport the viral particles to other diners, who otherwise had not had contact with each other – while the report found that those elsewhere in the restaurant that was not near the air flow did not get sick.
“Ventilation seems to play a role and that means transmission occurs through droplets in the air that people inhale or pick up in one way or another,” said Marr.
“The fact that ventilation seems to play an important role suggests that there is a transmission in the air. “
The World Health Organization says transmission of the virus by air “may be possible under specific circumstances”, such as intubating a patient in a hospital, but says there is no conclusive evidence that it can spread from person to person by air.
Yet even speaking can produce hundreds of tiny droplets that have the potential to carry viruses and can stay in the air for eight to 14 minutes, a new study in the Proceedings of the National Academy of Sciences (PNAS) found.
The research team did not study the droplets of speech of people who had COVID-19 specifically, but concluded that even one minute of talking out loud could generate more than 1,000 droplets that could carry the virus.
“At best, protecting yourself from a droplet infection is extremely complicated,” said Dr. Andrew Morris, a professor in the Department of Medicine at the University of Toronto who studies infectious diseases.
“One of the things that has been extremely consistent is that having people in tight spaces – especially to break bread, so to speak – has increased the likelihood of transmission. “
Lessons for Canada on Reopening
In the context of this growing body of research, officials from across Canada are launching slow and progressive reopenings that include many indoor environments.
Starting May 19 in Ontario, retail stores – but only outside shopping malls, with street entrances – can start reopening with physical distance measurements in place.
In Quebec, the return to a semblance of normalcy is happening on two levels: regions outside Montreal are reopening, but the provincial government has already twice delayed easing of restrictions in and around the city itself – the epicenter of the province’s COVID-19 cases.
And in British Columbia, restaurants, hair salons, retail stores, museums and libraries are all expected to reopen soon, although the ban on gatherings of more than 50 people will remain in place and discos and bars are expected to remain closed more long time.
Regardless of when these types of businesses officially reopen across Canada, research trends can help us determine which activities put Canadians most at risk, said Jason Kindrachuk, assistant professor of viral pathogenesis at University of Manitoba.
“It informs our decisions when we start to think about things like reducing [physical] distancing measures, “he said, adding that it means anything that can interact in stores or dine in a restaurant.
“Now we need to think of new strategies to use so that we can reduce these types of events.”
“Move as many activities outside as possible”
Kindrachuk said examples such as glass barriers for cashiers could be part of society’s “new normal” after the pandemic ended, and more people will reflect on the ease with which infectious diseases spread through the world. day by day.
“I think we will come back to many aspects of our lives where people are closely together,” said Morris.
“I don’t think anyone can imagine using a fully saturated and comfortable metro system right now. “
Morris said these types of social settings where people congregate en masse – such as schools, malls, stadiums and public transportation – will be a constant concern for the spread of the disease.
“Now the only way we can safely manage in the future is to bring ourselves to a very low level, to have continuous monitoring and to accept that – sometimes – people will infect others,” said he declared. .
“But if we have very good monitoring and follow-up of the contacts, we will be able to limit the extent of the spread once he looks up.” “
According to Marr, the simplest way to reduce transmission is to reconfigure our lifestyles to avoid crowded indoor places, especially those with poor ventilation.
Speaking of rallies this week, British Columbia provincial health worker Dr. Bonnie Henry said, “Outside, it’s always better than inside. “
Watch Dr. Bonnie Henry explain how to organize a barbecue safely:
It’s a decision that should prove easier in the summer months when restaurants and bars, for example, can potentially open patio seating.
“I think we should try to move as many activities outside as possible,” she said. “Obviously avoiding dense crowds is a good idea and paying close attention to ventilation in buildings is going to be helpful. “
Reconfiguring society in this way could give people outdoor options to resume a somewhat normal life, while reducing their risk of catching COVID-19.
“We can’t stop it,” said Marr, “but we can slow it down. “
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