Study suggests Covid-19 can spread faster in winter

Published Jul 11, 2020


CAPE TOWN- A Covid-19 study conducted in New South Wales, Australia suggests there could be some seasonal impact on the spread of the virus and that it could spread faster in periods of lower humidity during winter.



found an association between lower humidity and an increase in positive cases. Researchers said that if there is a one percent decrease in humidity it could increase the number of Covid-19 cases by six percent.

Epidemiologist in the Sydney School of Veterinary Science Professor Michael Ward said there are biological reasons why humidity matters in the transmission of airborne viruses.

"When the humidity is lower, the air is drier and it makes the aerosols smaller. When you sneeze and cough those smaller infectious aerosols can stay suspended in the air for longer. That increases the exposure for other people. When the air is humid and the aerosols are larger and heavier, they fall and hit surfaces quicker," he said.

In an


published on the World Economic Forum by Digital Editor John Letzing, he points out that another Southern Hemisphere data point can be found in South Africa. Earlier this month, that country reported its highest daily total of confirmed coronavirus cases to date, about two weeks after the winter solstice.

The scientific community remains to determine the exact relationship between seasonal change and the spread of the coronavirus. Last month the executive director of the World Health Organization’s (WHO) Health Emergencies Program said it was unclear how the arrival of winter in the Southern Hemisphere would affect the situation.

Letzing said that many experts have warned winter conditions could impact South Africa’s efforts to curb Covid-19 as more people may stay indoors in places heated by wood and coal stoves, which emit particulate matter that can further the spread.

The Spanish flu pandemic surged during the colder months of 1918 and 1919, which some have seen as an indication of what’s in store with Covid-19.

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