Warmer Weather May Slow, but Not Halt Coronavirus

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 percent 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 M.I.T. who is a co-author of the study. “You see this in Europe, even though the health care there is among the world’s best.”

The temperature dependency is also clear within the United States, Dr. Bukhari said. 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, the global AIDS coordinator in the United States and also 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.

Dr. Birx also noted that the pattern was similar with the SARS epidemic in 2003. But she stressed that because the virus outbreaks in China and South Korea began later, it was difficult to determine whether the new coronavirus would take the same course.