Summer is just around the corner, bringing hot weather, humidity and hopefully, lots of sunshine.
And as we face the prospect of a pandemic summer, researchers have been digging into whether the nice weather might affect the spread of the novel coronavirus, and what that means for COVID-19 in Canada.
Unfortunately, they say, it’s unlikely that sunshine will make the virus go away.
There’s not really any evidence to show that hot weather hurts the virus, according to Dr. Peter Jüni, a professor of epidemiology at the University of Toronto and St. Michael’s Hospital.
Hot countries like Singapore and Brazil have also experienced outbreaks, to begin with.
In a paper that Jüni co-authored for the Canadian Medical Association Journal, a country’s latitude and temperature didn’t appear to have much to do with how easily the virus transmitted.
“Our data indicate, and I think this is strictly solid, that temperature does not play any role in the epidemic growth of COVID-19,” he said.
“It will not be contained through the weather.”
The researchers did find some link to humidity, with a more humid environment seeming to be bad for the virus, but the link was weak and needs more research, he said.
For Dr. Lynora Saxinger, an infectious diseases specialist at the University of Alberta, it’s not so much that summer weather hurts the virus as that cooler, drier air — like we have in fall and winter — might potentially help it.
“Cold, dry air transmits more efficiently,” she said. “That would suggest we maybe see more COVID-19 in the cold, dry air scenario that we would expect in the coming fall-winter season, than we saw with the outbreaks over the summer. So it does raise the possibility of a worse second wave.”
What does change in summer, Jüni said, is people’s behaviour.
“That’s the big deal,” he said. “People go out, would be outside, always ventilated by the wind that is blowing.”
Evidence shows that most outbreaks have originated in indoor settings, not outdoors, said Saxinger. And people do tend to spend more time outside in the summer.
In winter, Jüni said, things are different. “If people are inside in masses inside badly ventilated rooms, touching more smooth surfaces that are contaminated with SARS-CoV-2, that’s the big problem. You have that much less in summer.”
As long as people continue to avoid big crowds and practice physical distancing while outside, the chance of transmitting the virus is lower, he said.
Some viruses, like influenza, do have a seasonal pattern, Saxinger said, but she warns that it’s unlikely we will see this regular seasonality in COVID-19 anytime soon, because it’s a brand-new virus.
“I think I kind of dismiss the seasonality issue to some extent when you’re looking at the influenza parallels, because this is a new virus and everyone is susceptible,” she said.
“Influenza is seasonal because we all have some partial immunity to it. And we’re also getting flu shots. And so it’s not just taking off to an entirely susceptible population.”
As a new virus, we’re all susceptible to the novel coronavirus though, so we aren’t protected by that kind of low-level immunity most people have to the flu, she said.
The virus isn’t going to go away anytime soon, Saxinger said. But while it’s at a lower level, we have a chance to prepare for what she thinks could be a difficult fall.
“I think it’s really important that people not get a false sense of security about, ‘Oh, it’ll just become gone in the summer’ because it won’t. And it hasn’t.”
This should include planning out ways to manage classrooms so that teachers don’t work with multiple groups of children, or cutting university classroom sizes and other such measures to ensure people aren’t congregating in large numbers in an enclosed space, Jüni said.
Saxinger warns that without careful planning, improved health care resources, and increased contact-tracing capability, we could be in for a rough second wave of the virus.
“I think we should try to enjoy the summer as much as possible because we might be going back into a situation where we’ll be monitoring really carefully for restrictions that need to be put back in place and really adhered to in the fall and winter.”
Questions about COVID-19? Here are some things you need to know:
Symptoms can include fever, cough and difficulty breathing — very similar to a cold or flu. Some people can develop a more severe illness. People most at risk of this include older adults and people with severe chronic medical conditions like heart, lung or kidney disease. If you develop symptoms, contact public health authorities.
To prevent the virus from spreading, experts recommend frequent handwashing and coughing into your sleeve. They also recommend minimizing contact with others, staying home as much as possible and maintaining a distance of two metres from other people if you go out. In situations where you can’t keep a safe distance from others, public health officials recommend the use of a non-medical face mask or covering to prevent spreading the respiratory droplets that can carry the virus.
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