Here's How Winter Could Make the Coronavirus Pandemic Even Worse

Lower humidity means an increase in COVID-19 cases, according to a new study.

As temperatures heat up, many have optimistically wondered if warmer weather will bring the coronavirus pandemic to a close. The science, sadly, does not support that—summer will not end coronavirus, and there's another season on the horizon that could make the situation even more dire. While experts predict second and third waves of the virus, new research shows that the end of the year could see a serious uptick in COVID-19 cases. As bad as things may seem now, one study suggests that winter could make the coronavirus pandemic even worse.

The peer-reviewed University of Sydney study, published June 2 in the journal Transboundary and Emerging Diseases, found that lower humidity was associated with more people testing positive for coronavirus. Specifically, a 1 percent decrease in humidity could raise the number of COVID-19 cases by 6 percent. Given that humidity drops significantly in the winter, this research lends credence to the belief that coronavirus could become a seasonal virus—with winter as the season to be especially vigilant during.

"COVID-19 is likely to be a seasonal disease that recurs in periods of lower humidity," study leader Michael Ward, an epidemiologist in the Sydney School of Veterinary Science at the University of Sydney, said in a statement. "We need to be thinking if it's winter time, it could be COVID-19 time."

white woman in winter coat wearing a face mask in the snow

Researchers have been working to determine a correlation between coronavirus and the weather, but the results so far have not been promising for those hoping heat would have a serious impact on slowing the virus' spread. As a recent study published in the journal Clinical Infectious Diseases showed, COVID-19 cases do decease with warmer temperatures, but only up to 52 degrees Fahrenheit. After that, the difference is insignificant.

What the University of Sydney study found is that it's not the heat, it's the humidity—or the lack thereof. "When it comes to climate, we found that lower humidity is the main driver here, rather than colder temperatures," Ward said.

And there's a reason for that, he explained. "When the humidity is lower, the air is drier and it makes the aerosols smaller," Ward said. "When you sneeze and cough those smaller infectious aerosols can stay suspended in the air for longer. That increases the exposure for other people. When the air is humid and the aerosols are larger and heavier, they fall and hit surfaces quicker."

The good news, then, is that while the warmer temperatures of summer might not have any bearing on COVID-19 transmission, the heightened humidity could have a positive impact. On the flip side, however, low humidity can happen at any time of year, which means that while the study predicts winter will be worse, there could be increased danger whenever the humidity drops—whether that's in winter, spring, summer, or fall.

And for more on the future of COVID-19, Here's When a Third Wave of Coronavirus Could Hit, Doctors Say.

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