While virologists and epidemiologists have hypothesized that summer would subdue the worst of COVID-19’s transmissibility, recent case spikes in places like Arizona, Florida and Texas make it clear that the warmer summer season itself will not stop the virus from spreading.
“At this point, we need to do more in understanding the underlying determinants of spikes—and these are complex including individual, population, and environmental determinants similar to other respiratory viruses,” said Dr. Stefan Baral, an epidemiologist at Johns Hopkins University who has studied the links between the virus’ spread and environmental factors. “But yes, I still do think that an element of this has to do with environmental conditions.”
To be clear: it’s not the warmer weather itself that’s boosting transmission rates and cases. But, warmer summer weather is also not serving as the pause button for the virus’ spread.
The spike in cases crosses several other meteorological parameters, as well: more humid places, like Florida, are seeing spikes similar to those in hot and dry places, like Arizona and Utah.
That said, researchers continue to believe that colder and drier weather does increase the virus’ transmissibility, generally making it more seasonal and similar to the flu in that sense.
“Thus far, I have not seen any substantial data to refute our hypothesis that low temperatures and specific humidity lead to increased risk of transmission,” said Dr. Mohammad Sajadi, an associate professor of human virology at the University of Maryland, who has extensively studied links between the spread of coronavirus, latitude and weather.
“At a certain point, unless strict public health measures are implemented and followed, the healthcare system still gets overwhelmed,” Sajadi said.