New study finds a link between COVID-19 and low humidity

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A 1% decrease in humidity increases the number of COVID-19 cases by 6%.

That was the probability suggested by a new Australian study published in Australia Transboundary and emerging diseasesThis led to an association between lower humidity and an increase in COVID-19 positive cases.

Senior Researcher Professor Michael Ward, an epidemiologist at the University of Sydney’s School of Veterinary Medicine (USYD) and his team, was on February 26th in the Greater Sydney area of ​​New South Wales, mainly 749 in the Sydney area of ​​NSW. We investigated locally acquired cases of COVID-19. March 31st.

They matched each patient’s zip code with data from the nearest weather station to study rainfall, temperature, and humidity during the January-March period.

“Since the pandemics in China, Europe, and North America occurred in winter, we were interested in seeing whether the association between COVID-19 cases and climate differed in late summer and early fall in Australia,” Ward said. The professor said. newsGP..

“Humidity during that period was the most important factor explaining when the incident occurred. About two weeks before each case.”

Similar findings Science Direct Last month, USYD and its partner institution Fudan University suggest that low humidity promoted infection of COVID-19 cases in China. It was also linked to lower daily temperatures, which did not emerge as a factor in Sydney-based research.

Professor Ward says that’s not surprising.

“Looking at a Chinese study, these temperatures were fairly cold, as they were between 3 and 6 degrees Celsius. In Australia, it’s not so cold, so you might not see the effect of that strong temperature, Still, it may just be affected by humidity,” he said.

“But in New South Wales, it’s not winter yet.”

The biological theory behind the role of humidity is the same as respiratory infections of other airborne viruses such as influenza.

“At low humidity, there is not much water vapor in the air. Therefore, the air is very dry, and when someone coughs, especially infectious people, will take up aerosolized particles into the air. “, says Professor Ward.

“When the air is dry, those particles are so small that they can stay suspended in the air all the time.

“In high humidity and large amounts of water in the air, these particles are very large, heavy, and fall fairly quickly. This reduces potential exposure and infection to other people. “

Professor Michael Ward and his team studied 749 locally acquired coronavirus cases.

The theory seems to apply to the Northern Territory. 29 cases It has been recorded and there are no dead. Similarly, in Cairns and Townsville in North Queensland, Total 58 There are no cases and no dead.

However, it is difficult to articulate whether the decline is due to climate change or to public health efforts such as measuring social distances and closing borders.

Professor Ward says time and more data will tell, but for countries like Australia, which has several different climate zones, it’s difficult to generalize.

“There’s a wide range of humidity and temperature themes here, but there’s a local context of what’s going on,” he said.

“Inland Australia actually has the lowest summer humidity, but Sydney along the coast has the highest summers and the lowest winters, so there are some regional differences, even within the same state. .”

Studies to date have shown that the population of the southern coastal region of Australia is at greatest risk as winter approaches.

Although Australia has a relatively small number of cases and helps pave the way for mitigation of social distances towards winter, Professor Ward says the study emphasizes the need for caution.

“It’s about really strong surveillance, keeping hygiene and limiting,” he said.

“We know that as we enter the winter, they alleviate, but be aware that the conditions have become contagious, and remember if the winter requires any tailoring restrictions. Please keep it.

“But it’s a big public health issue with messaging to convey that we have to take different actions in summer and winter. This is a real challenge for public education.”

While Ward and his team are currently exploring case data for April and May, they focus on regional differences between relatively close but climatically distinct regions such as Sydney and Blue Mountains. Is beginning to

However, if the infection rate in the Australian community remains low, Professor Ward could fall into the ironic situation that researchers focused on the local context do not have enough data to assess the big picture. There is a nature.

“Because there were another 450 cases in April and May, that’s a little more than half the case in February and March,” he said.

“There are still a lot of cases to investigate, but then I’m getting 1 and 2 for locally acquired cases. It really is, if it continues in the middle of winter, to see if it really is That is not the case for climate change impacts.

“Public health interventions have overwhelmed the underlying climate impacts. This is good, but not suitable for research.”

RACGP has more information on coronaviruses. That website..

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