"And by the way, the virus, they're working hard, looks like by April, you know in theory when it gets a little warmer it miraculously goes away," Trump said during New Hampshire rally in February. "I hope that's true. But we're doing great in our country ... I think it's going to all work out fine. Rough stuff, I tell you, rough, rough stuff."
Experts, however, have pushed back on this theory. Though evidence suggests COVID-19 survives much longer in cooler, drier climates, researchers say it's unlikely humidity and warm temperatures will eradicate the disease. Findings published by MIT found that 90 percent of coronavirus transmissions recorded through March 22 occurred in regions with temperatures between 37.4 and 62.6 degrees Fahrenheit. While countries in the Southern Hemisphere, where average temperatures surpassed 64.4 degrees, accounted for fewer than 10 percent of global cases. It's important to take the number of confirmed cases with a grain of salt, as a country's reported low infection rate could be attributed to its poor public health infrastructure and lack of testing.
Analysts in Hong Kong have also found that an increase in temperature shortened the timeframe Sars-Cov-2 could be detected. A study published by Lancet Microbe on April 2 states that the virus was "highly stable" when left at at 39 degrees Fahrenheit after two weeks, but when left at 158 degrees, the pathogen was inactive after five minutes.
"Our most striking observation to date is the powerful effect that solar light appears to have on killing the virus both on surfaces and in the air," William Bryan, head of science and technology at the Department of Homeland Security, said in a statement to BuzzFeed News. "We’ve seen a similar effect with both temperature and humidity as well, where increasing temperature, humidity, or both is generally less favorable to the virus."
Ecological modelers at the University of Connecticut also released a study, which has yet to be peer-reviewed, that found ultraviolet light was effective in killing the virus; however, experts cautioned that too much exposure to UV-rays can cause skin cells to become cancerous.
So if research has found coronavirus is harmed by heat, humidity, and sunlight, it would seem as though the pandemic would end once we roll into summer, right? Researchers aren't convinced. Though environment appears to play a role in how long the virus can survive, many experts say human behavior is likely much more important when it comes to combatting coronavirus. Why? Because there's still a lot of questions surrounding disease and how it's transmitted.
If it takes a lot of virus to get someone infected, [David Relman, a professor of microbiology and immunology at Stanford University] explained, then perhaps the combined impacts of sunlight, humidity, and temperature on the virus’s survivability can greatly cut down transmission. But if it only takes a little bit of virus, especially small particles of the virus that can stay aloft in the air for hours, you’ll still see transmission inside the offices, restaurants, and movie theaters people will be spending time in, regardless of the weather outside.
It's also important to consider the way humans' behavior changes with each season. Though many viruses tend to thrive in winter months, most individuals tend to stay in-doors and at home to avoid the cold weather. This isolation could slow the spread of infection, but the indoor circulation of germs and bacteria could also result in a weaken immune system. On the other hand, people tend to spend more time outdoors and in public spaces during the warm-weather months. The increase in social interaction could lead to a spike in transmission; but will the summer climate lower the risks of infections? At this point, we'll have to wait and see.
"Weather and climate can only explain part of the transmission, the other factors are nonenvironmental — social distancing, washing hands, covering your cough, staying home when you are sick — and these factors are probably the most important in a pandemic," Jesse Bell, a climate health expert at the University of Nebraska, told BuzzFeed. "Understanding climate and weather will only tell you when the environmental conditions are optimal for the spread of the virus."