Communities living in warmer places appear to have a comparative advantage to slow the transmission of coronavirus infections, according to an early analysis by scientists at the Massachusetts Institute of Technology.
The researchers found that most coronavirus transmissions had occurred in regions with low temperatures, between 37.4 and 62.6 degrees Fahrenheit (or 3 and 17 degrees Celsius).
While countries with equatorial climates and those in the Southern Hemisphere, currently in the middle of summer, have reported coronavirus cases, regions with average temperatures above 64.4 degrees Fahrenheit (or 18 degrees Celsius) account for fewer than 6% of global cases so far.
"Wherever the temperatures were colder, the number of the cases started increasing quickly," said Qasim Bukhari, a computational scientist at MIT who is a co-author of the study.
Southern states, like Arizona, Florida and Texas, have seen slower outbreak growth compared with states like Washington, New York and Colorado. Coronavirus cases in California have grown at a rate that falls somewhere in between.
The seasonal pattern is similar to what epidemiologists have observed with other viruses. Dr. Deborah Birx, a member of the Trump administration's coronavirus task force, said during a recent briefing that the flu, in the Northern Hemisphere, generally follows a November to April trend. The four types of coronavirus that cause the common cold every year also wane in warmer weather.
The possible correlation between coronaviruses cases and climate should not lead policymakers and the public to complacency.
"We still need to take strong precautions," Bukhari said. "Warmer temperatures may make this virus less effective, but less effective transmission does not mean that there is no transmission."
Warmer temperatures might make it harder for the coronavirus to survive in the air or on surfaces for long periods of time, but it could still be contagious for hours, if not days, Bukhari said.
And because so much is unknown, no one can predict whether the virus will return with such ferocity in the fall.