It's usually what happens with the flu—will the coronavirus follow suit?

By Leah Groth
Updated April 09, 2020
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It's April, and you know what that means: Spring is here, the weather will start warming up, and that nasty seasonal flu virus will start fading away a bit. All good news—but what about that other virus we've been dealing with? As springtime approaches and the temperature begins to rise, will SARS-CoV-2—the virus at the root of the 2019 coronavirus disease (COVID-19)—also be affected?

Unfortunately, no one knows for sure—and even experts can't seem to agree on whether or not warmer weather will slow down the coronavirus.

According to a new article in National Geographic, viruses that cause influenza or milder coronaviruses (yes, there are seven in total that affect humans, some much less concerning than others) often subside in warmer months due to a concept called "seasonality," or a predictable rise and fall depending on the time of year. That seasonality also has to do with how certain viruses respond to heat and humidity, along with the fact that when the temperature rises, people spend less time inside where viruses can more easily spread.

However, because SARS-CoV-2 is so new, there's no way to say for sure whether the virus will experience the same seasonality as other viruses. "I hope it will show seasonality, but it’s hard to know," Stuart Weston, a postdoctoral fellow at the University of Maryland School of Medicine, where the virus is being actively studied, explained to the magazine.

Maciej F. Boni, an associate professor of biology at Penn State University, also pointed out to the Philadelphia Inquirer that there is one major difference between the novel coronavirus and the flu: immunity. While many of us have built up an immunity to the flu, this isn’t the case with the new illness. Basically, SARS-CoV-2 is encountering a "completely susceptible" US population. "We’re not off the hook just because we’re getting to springtime and the warmer weather," he explained.

Still, some experts are decidedly more optimistic. According to Jeremy Brown, MD, director of the Office of Emergency Care Research at the National Institutes of Health and author of Influenza: The Hundred-Year Hunt to Cure the Deadliest Disease in History, similar to the flu, COVID-19 will not survive as readily in warmer temperatures. “COVID-19 will slowly recede as the warmer spring climate provides conditions that the virus cannot tolerate,” he tells Health. "Spring will be very welcome this year."

Some new research—specifically an early analysis by scientists at the Massachusetts Institute of Technology—echoes this idea, reporting that most coronavirus cases had spread in areas with lower temperatures (between 37.4 and 62.6 degrees Fahrenheit). Conversely, while there have been reported coronavirus cases in countries with in the Southern Hemisphere (and in the middle of summer), cases in regions with temperatures over 64.4 degrees Fahrenheit account for less than 6% of cases globally so far.

A review published April 7 by the National Academies of Sciences, Engineering, and Medicine (NAS) fails to provide clarity one way or another. According to NAS, there's some data to support waning cases of viral illness in warmer and more humid climates, but none of the studies are without limitations. "Given that countries currently in 'summer' climates, such as Australia and Iran, are experiencing rapid virus spread, a decrease in cases with increases in humidity and temperature elsewhere should not be assumed," according to the report.

NAS concluded that many factors other than weather and humidity may play a role in human-to-human transmission of SARS-CoV-2, and it noted that additional studies on the current pandemic may shed light on the effects of climate.

Bottom line: no one knows exactly how COVID-19 will react to warmer temperatures in the US —which means that you definitely shouldn't begin letting your guard down just because it's warming up outside.

Instead, experts agree that everyone should continue to follow the preventive measures recommended by the Centers for Disease Control and Prevention, which include: avoiding close contact with people who are sick; cleaning and disinfecting frequently touched objects and surfaces; and washing your hands often with soap and water for at least 20 seconds, especially after going to the bathroom and before eating.

The information in this story is accurate as of press time. However, as the situation surrounding COVID-19 continues to evolve, it's possible that some data have changed since publication. While Health is trying to keep our stories as up-to-date as possible, we also encourage readers to stay informed on news and recommendations for their own communities by using the CDC, WHO, and their local public health department as resources.

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