Coronavirus Outbreak: Warm and humid weather can slow spread of COVID-19 cases, says MIT study, but precautions still necessary

FP Staff

The spread of the novel coronavirus may be slower in warm and humid conditions, a recent study by two Massachusetts Institute of Technology (MIT) researchers has found.

The correlation holds out hope for tropical countries like India but it means that countries in Europe and North America may not get much relief on account of environmental factors.

The study, authored by Qasim Bukhari and Yusuf Jameel, said, "it appears that the spread of 2019-nCoV (COVID-19) might be influenced by environmental factors. Based on the current data on the spread of (COVID-19), we hypothesise that the lower number of cases in tropical countries might be due to warm humid conditions, under which the spread of the virus might be slower as has been observed for other viruses."

On the other hand, it also said, "Our analysis shows that the chances of reduced spreading due to environmental factors would be limited across most of northern Europe and North America (USA and Canada) in summer."

The study was based on an analysis of the local weather patterns of regions affected by the novel coronavirus. The results indicated that till 22 March, 90 percent of COVID-19 transmissions occurred within a certain range of temperature (3 to 17 degrees Celsius) and absolute humidity (4 to 9 g/m3). On the other hand, countries with a mean January-February-March temperature of over 18 degrees Celsius and absolute humidity of over 9 g/m3 have reported less than 6 percent of the total cases.

It further noted, "It could be argued that it may be due to lower number of testings such as in India, Pakistan, Indonesia and African countries but many countries such as Singapore, UAE, Saudi Arabia, Australia, Qatar, Taiwan and Hong Kong have performed more 2019-nCoV tests per million than the US, Italy and several European countries, suggesting that non-testing is not an issue at least for the countries listed above."

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However, the researchers said that while there is a relation between heat and humidity and lower numbers of novel coronavirus cases, the "underlying reasoning behind this relationship is still not clear."

The study stresses on the importance of ensuring quarantine measures  and putting in place appropriate public health interventions even in hot and humid conditions but said that the relation between heat and humidity, and the novel coronavirus should be closely monitored. It says, "If a strong environmental dependence in the spread of 2019-nCoV emerges, then it should be used to optimise the 2019-nCoV mitigation strategies.

This is not the first time that health experts have hinted at a connection between heat and lower prevalence of COVID-19. A report in CBS News has quoted Dr. Gregory Gray of Duke University's Global Health Institute Division of Infectious Diseases, as saying that the summer months may lead to a small decrease in transmission, but likely won't stop the spread of coronavirus completely.

India Today quoted AIIMS director Randeep Guleria as saying that while hot and humid weather would not "kill" the novel coronavirus, it may decrease its transmissibility.

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