Most experts are in agreement over the fact that hot weather plays a small role in slowing down coronavirus transmission. As the summer season is upon the country, this is bad news for Americans who are going back to old ways of living without social distancing.
Studies done so far have not made statistically significant revelations showing the impact of temperature on the pandemic. Several research papers on the subject are also awaiting peer-review, thus nothing conclusive can be said as of now.
One study conducted by the Massachusetts Institute of Technology (MIT) said that their research does not “suggest that 2019-nCoV would not spread in warm humid regions.”A crucial factor behind the low number of cases in certain countries could be related to the medical infrastructure available for testing. Tropical countries with high populations such as Brazil and India may not be able to test all citizens due to limited testing capacity, the researchers noted.
The paper also pointed out a contradiction on the assumption that it is the ease of mobility that exists between China and Western countries that caused the disease to spread faster. That may not be correct, primarily because China equally enjoys human mobility with Southeast Asian countries. Additionally, travel restrictions and social distancing measures determine transmission rates too hence generalizations based on temperature can never be completely accurate.
Despite the aforementioned limitations, temperature analysis done by scientists Qasim Bukhari and Yusuf Jameel, both MIT researchers, showed that a minor correlation between temperature and coronavirus spread existed. When they monitored cases from Jan. 22 to March 21 for 10-day period at a time, a spurt in cases was observed in areas having an average temperature between 4°C and 17°C and absolute humidity from 3 to 9 g/cubic meter.
Another research project helmed by Harvard University researchers examined the relationship between temperature and transmission rate in 3,739 global locations.
“We find a strong association between temperatures above 25°C and reduced transmission rates, and a weaker effect below 25°C. These suggest many temperate zones with high population density may face larger risks in winter, while some warmer areas of the world may experience slower transmission rates in general,” the researchers stated in their paper. “The U-shaped relationship between UV index and transmission may help more temperate regions during summer, but higher risks in equatorial regions with very high UV exposure.”
In all the findings, a 30 to 40 percent lowering of the transmission rate was observed in some places. However, Mohammad Jalali, researcher at Harvard Medical School, told Scientific American that a mere 40 percent reduction does not make a difference since COVID-19 cases can still exponentially rise.
“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 told the New York Times. “Warmer temperatures may make this virus less effective, but less effective transmission does not mean that there is no transmission.”