Claims the spread of COVID-19 could be suppressed like influenza by regulating indoor humidity need to be investigated, say Australian experts.
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The theory is based on 2013 research showing patients are safer from the flu in a room set at higher relative humidity than a dry one.
The US Centers for Disease Control and Prevention study found more than 75 per cent of influenza particles were able to cause infection an hour after being coughed into an area where humidity levels were 23 per cent.
When the levels were raised to 43 per cent, just 14 per cent of the particles were infectious.
While potentially significant, Adelaide University Research Centre for Infectious Disease deputy director Michael Beard says the idea humidification might subdue COVID-19 needs analysis.
"It seems to be that this virus is a little bit hardier or a little more resistant to some of the external forces that might cause it to degrade," he says.
"I think influenza is a lot more susceptible to changes in temperature and humidty. But I think this is a really good starting point."
While it's far from settled science, evidence has emerged that the coronavirus prefers dry conditions.
Data collected by Nanjing University from more than 500 locations across the globe since late January suggests weather, including relative humidity, is a factor in the spread of the contagion.
Researchers from universities in Madrid and Helsinki are also reporting that tropical parts of the globe seem least affected.
That's enough to indicate one of the best ways to combat COVID-19 is to set humidity levels inside hospitals, schools, offices and homes between 40 and 60 per cent, claims American researcher Stephanie Taylor.
"As human beings we don't do well in dry air and quickly-mutating viruses and bacteria do," says the Harvard Medical School and architecture graduate who also hosts a daily coronavirus Youtube blog.
The more moisture in the air, the harder for airborne pathogens to land beyond the 1.5m zone which constitutes our 'personal space' and to keep settling and resuspending which makes surfaces hard to sterilise, she says.
They also die off faster.
At the same time, our skin doesn't dry and crack, our lungs better repel the pathogens that fasten themselves via our airways and our organs don't weaken due to dehydration.
Dr Taylor says the problem especially during winter is that we come inside, put our heaters on and push humidity levels down to 20 per cent.
Extrapolating what's known about the flu and applying it to coronavirus might work, Prof Beard concedes.
"I think the data is relatively strong for influenza so it could potentially be the same and (what we know) could help," he told AAP.
"But I'd be cautious."
Monash University's Professor Paul Komesaroff agrees.
"It's been an issue that's important enough to think through in terms of the flu virus, so there's no reason why one wouldn't pursue it in relation to the coronavirus," he said.
"It's clear we just don't know the answer at this stage but I would say it's ripe for research."
Australian Associated Press
