A study published Thursday suggested that COVID-19 thrives in cooler, drier weather, the latest volley in an ongoing scientific debate over whether the coronavirus is affected by seasonal changes.
The analysis, published by a team out of the University of Maryland, found that hard-hit cities around the globe were within a band between 30 and 50 degrees North, while 42 other cities that seemed to avoid the worst of the pandemic were to the north or south of them.
“The distribution of substantial community outbreaks of COVID-19 along restricted latitude, temperature, and humidity measurements was consistent with the behavior of a seasonal respiratory virus,” the authors wrote in the study, published online by the Journal of the America Medical Association.
The eight cities examined within the band were Wuhan, China; Tokyo, Japan; Daegu, South Korea; Qom, Iran; Milan, Italy; Paris, France; Seattle, Washington; and Madrid, Spain. All of them had temperatures between 41 to 51 degrees Fahrenheit and relative humidity between 44 and 84 percent when the virus was spreading most rapidly.
“We think the SARS-CoV-2 virus has a more difficult time spreading in conditions with higher temperature and humidity,” study co-author Dr. Mohammad Sajadi told UPI.
He added that researchers could use climate modeling to predict where the virus might break out next, but cautioned that more work needed to be done.
Some experts have suggested that hotter temperatures can affect the spread of the virus, though others say the climate is not a major factor. In Israel, Prime Minister Benjamin Netanyahu has insisted that heat does not affect the virus.
The authors noted in the study that coronaviruses that cause the common cold in humans “have been shown to display strong winter seasonality between December and April and are undetectable in summer months in temperate regions of the northern hemisphere.”
Maps produced by the research team showed a green band of moderate weather across the northern hemisphere that forms a sort of Goldilocks Zone for the virus, and which all eight cities fell into. Israel is just to the south of the zone.
It claimed that cities near virus centers but outside the temperate zone appeared to have fared better than those within it, though the study only includes data up to March 10. Among the cities listed as not having major outbreaks is Jerusalem, though Israel’s worst-hit city saw most of its infections only starting in late March and April.
The model conforms with major outbreaks in several cities in March and April based on the climate data, including London, Berlin, New York and Beijing.