Southern hemisphere winter may spur rise in Covid-19 cases, study says
- Research in Australia suggests a 1 per cent fall in humidity could increase number of infections by 6 per cent
- Findings echo fears that there could be worse to come for countries heading into drier, cooler months
The study was based on an analysis of all 749 local Covid-19 cases in New South Wales state from January to March, correlated against weather conditions in the areas of infection. It suggests that a 1 per cent fall in humidity could increase the number of infections by 6 per cent.
Lower humidity allowed the virus to stay airborne for longer, increasing the potential for exposure, said Professor Michael Ward, a zoonotic disease expert at the University of Sydney who led the peer-reviewed study. High humidity caused the virus to fall to the ground quicker, he said.
Ward ran the study with researchers at the Department of Epidemiology and Health Statistics of Fudan University in China. It was a follow-up to peer-reviewed work with Fudan in January and February that analysed how temperature and humidity affected Covid-19 transmission in mainland China in the northern hemisphere winter.
“We found low humidity plus low temperature to be drivers of Covid-19,” Ward said of the study in China, published in April in the journal Science of the Total Environment.
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But the latest research in Australia found that only lower humidity was associated with an increase in Covid-19 cases, not temperature.