It's summertime and Americans are out and about again. For now, the pandemic is slowing down in the U.S. and other countries that were hit hard and early.
But the virus is actually expanding worldwide, with new hot spots in Latin America, Africa and Asia. Some of the fastest virus surges — in Chile, Peru and Brazil — are happening in the Southern Hemisphere just in time for winter.
"It's going to be perhaps a little bit like the flu that we get a winter period of risk," said Dr. Michael Ward, a Veterinary epidemiologist at the University of Sydney.
Ward recently published a peer-reviewed study suggesting COVID-19 could be a seasonal illness with a higher risk of infections in winter.
"It's going to be local and it's going to depend on local conditions. But probably humidity is an underlying factor, and temperature could be, we're not sure yet," Ward said.
The study analyzed hundreds of locally acquired COVID-19 cases in the Sydney area. It found a 1% drop in humidity increased the number of infections by 6%. Ward says lower humidity enables the virus to stay airborne for longer.
"So when someone sneezes, for example, there's a release of a lot of aerosols, and they stay suspended in the air. When the air is dry, they stay in the air for longer. When the air is wet, these particles tend to be bigger and they just drop much more quickly," explained Ward.
The growing body of evidence on the link between the climate and the virus, and the fact that people spend more time indoors in winter, could be bad news for some Southern Hemisphere countries.
"In Australia, we don't have many cases now. So if we keep a very tight lid on the cases, we probably shouldn't see a second outbreak. Other countries like Brazil, where we've seen this huge number of cases, maybe what that's saying is if you have an outbreak that essentially hasn't been controlled and then you enter a higher-risk period, you get a really bad outcome," Ward said.
And for people like me enjoying the warm and humid weather in the Northern Hemisphere, it's crucial to remember that summertime does not at all eliminate the risk of infection.
"We would say, sort of, summer is a lower risk and it's probably a time for making sure surveillance is still up to scratch and you're getting prepared for winter," Ward said.
Ben Schamisso, Newsy, Chicago