Warmer temperatures may not impact COVID-19 cases, study finds

There is likely no significant association between temperature and incidence of the novel coronavirus (COVID-19), according to new research from the Fudan University in Shanghai and published in the European Respiratory Journal.

Previous studies showed the importance of weather variables in the transmission of infectious diseases, including influenza and severe acute respiratory syndrome (SARS). Therefore, it was hypothesized that COVID-19 transmission may decrease or even disappear when temperature and UV radiation increase in the summer, the researchers said.

In the study, researchers led by Weibing Wang, MD, PhD, collected COVID-19 confirmed case information from 224 cities with at least 10 cases as of March 9 in China reported by the National Health Commission and the Provincial Health Commissions of China. The researchers calculated the basic reproduction number (R0) for 62 cities with more than 50 cases as of February 10.

The research highlighted meteorological data, including daily mean temperature and relative humidity, from the China Meteorological Data Sharing Service System. The team measured daily temperature, maximum temperature, minimum temperature, relative humidity, and UV radiation for the 224 cities from January to March.

The study found no significant associations between temperature and COVID-19 incidence rates, even after adjusting for relative humidity and UV radiation. UV radiation, after adjustment for relative humidity and temperature, was no associated with cumulative incidence rate. They also found no associations between relative humidity, maximum temperature, and minimum temperature with either COVID-19 incidence rate or basic reproduction number.

The results from the study do not follow the expected pattern, researchers said, which show a relationship between respiratory-borne infectious diseases and temperature, indicate that both SARS and influenza need to survive under certain temperature conditions, and increasing temperature can reduce the ability of the SARS virus and influenza virus to spread.

The study limitations include the study period potentially not representing a whole meteorological pattern associated with transmissibility of COVID-19. The researchers conclude the study does not support the hypothesis that high temperature and UV radiation can reduce the transmission of COVID-19.

“It might be premature to count on warmer weather to control COVID-19,” the researchers said.

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