Cases of influenza wane with the arrival of summer in the northern hemisphere. Could the same seasonality hold true for the novel coronavirus? Experts are unsure.
It has been called a dangerous combination—heat and humidity so extreme that sweat does not evaporate sufficiently to cool the human body, leading to exhaustion and, worse, heat stroke.
But with the nation still in the grips of a deadly pandemic that has claimed tens of thousands of lives, ironically, many people are now asking: Will summer’s blistering temperatures and high humidity, which can trigger a host of illnesses but also kill viruses that cause influenza, help save us from COVID-19?
The answer, according to a pair of University of Miami experts, isn’t clear.
“There are a dozen or so respiratory viruses that circulate in the winter. Then we typically see a drop-off in the summer that’s usually more pronounced in the more temperate parts of the country like the Northeast,” said Dr. Bhavarth Shukla, assistant professor of medicine and medical director of UHealth Infection Control. “There is some hope that this virus will be seasonal as well.”
Don’t count on it, though.
While COVID-19 belongs to a family of viruses that can’t withstand heat, “the issue with this particular virus is that since it’s novel, we’re not really sure how it will behave in the same setting as other viruses,” said Shukla.
He noted other factors that could determine when and how quickly the virus is stopped—among them, whether herd immunity will be achieved.
Also known as community immunity, herd immunity occurs when the majority of a population, either through vaccination or prior illness, becomes immune to a disease, stopping its spread.
A Washington state man in his 30s became the first confirmed case of COVID-19 in the U.S. last January. So, the virus is believed to have been circulating in the nation for only about four months. “Now that it’s been in the community, will the people who have recovered develop a short-term or a long-term immunity to the virus? It’s still too early to tell,” Shukla said.
In Wuhan, China, where the virus originated, officials have begun testing residents for antibodies to get a better idea of immunity levels and to try to prevent a second wave of the disease.
Another uncertainty: whether having immunity to other coronaviruses will help people become resistant to COVID-19—what’s known as cross-reactive immunity.
But as summer quickly approaches, it is the effect of heat on the virus that is arguably the biggest unknown.
Last year, the Northern Hemisphere had its hottest summer on record since 1880, according to data from the National Oceanic and Atmospheric Administration. And, this summer could be another record-setter.
“The North American Multi-Model Ensemble predicts a warmer-than-average summer for most of the United States, especially the West and the Northeast,” said Emily Becker, associate scientist at the University of Miami’s Rosenstiel School of Marine and Atmospheric Science, who specializes in sub-seasonal and seasonal climate prediction and predictability.
“There is a strong probability that the Caribbean and North Atlantic will be warmer than average through the summer and into the fall as well,” she said. “A rainier summer is predicted for the Southeast, and there’s some likelihood that the Pacific Northwest will be drier than normal.”
While warmer temperatures could have some impact on the survivability of COVID-19, the nation shouldn’t be lulled into the idea that a summer swelter will stop the virus in its tracks, said Naresh Kumar, an associate professor of environmental health in the Department of Public Health Sciences at the Miller School of Medicine. Even in the harsh heat of summer, he warned, some viruses can still spread, surviving for longer periods of time in the cool-temperature and low-humidity environments of air-conditioned settings.
An infected person could touch a button inside an elevator located in an air-conditioned office building, putting at risk other individuals who may press the same button and then touch their eyes, nose or mouth, Kumar explained.
“How long the virus can live on the surface of certain objects will not depend on whether it is summer or winter, but more so on the temperature inside the building,” he said.
And for that reason, Kumar said, it is important to adhere to social distancing and health safety guidelines. Be sure to wear a mask in public, he warned. And, use caution, especially when it comes to touching objects. Be sure to wash or sanitize your hands often.