High ambient temperature and high humidity reduce the transmission of COVID-19

It is a well known fact that Influenza infection is seasonal. Influenza cases rise during winter season when it is cold and dry. There are multiple studies showing that variations like temperature and humidity have a major impact on seasonal influenza. During cold weather, Influenza virus is more stable and cold weather may also weaken our immunity. There has been an interest in similar findings with COVID-19 infection.

Wang et al. studied the effects of temperature and humidity and how they affected the transmission rates of COVID-19 among 100 cities in China. They calculated the reproductive number, R, for each of all 100 chinese cities with more than 40 cases. R indicates how fast the COVID-19 illness spreads in the community. They concluded that for every degree Celsius rise in temperature and percent increase in humidity, reproductive number, R, reduced proportionately. They predicted that summer and rainy season may effectively reduce the transmission of the COVID-19.

While this study gives some assurance that COVID-19 pandemic may slow down during the summer months, it also depends on several other factors like social distancing, regular hand washing, personal hygiene, disinfecting commonly used objects and strict quarantine for all affected people. Temperature and humidity are only two of the several factors that influence the transmission of COVID-19. When other precautions are not taken appropriately, it can definitely spread even in hot and humid conditions.

References:

1. Wang, Jingyuan and Tang, Ke and Feng, Kai and Lv, Weifeng. High Temperature and High Humidity Reduce the Transmission of COVID-19 (March 9, 2020). Available at SSRN: https://ssrn.com/abstract=3551767 or http://dx.doi.org/10.2139/ssrn.3551767
2. Quantifying the role of weather on seasonal influenza. Roussel M et al. BMC Public Health. 2016 May 26;16:441. doi: 10.1186/s12889-016-3114-x.

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