Members of the Australian Health Protection Principal Committee’s infection control advisory group met on Wednesday to debate the issue, after the World Health Organisation issued a statement acknowledging “evidence emerging” of the airborne spread of SARS-CoV-2.
The advisory group’s chairwoman Lyn Gilbert, an infectious disease expert and Honorary Professor at Sydney University, said there was still “a lot of debate” about the appropriate use of masks within the medical community, but her position had not changed.
She said while surgical or cloth masks could be helpful for people who “can’t maintain physical distancing”, it was best to avoid crowded environments wherever possible and masks were of limited use when people often did not wear them correctly.
Professor Gilbert said there should be no change to hospital procedures, where P2 and N95 respirator masks were reserved for clinicians treating COVID-19 patients on respirators in intensive care, with staff treating infected patients in ward beds given only surgical masks.
Prime Minister Scott Morrison said the national cabinet would continue to be guided by the AHPPC’s expert advice on the use of masks.
Professor Gilbert said there was “nothing new” in the WHO’s statement acknowledging evidence of airborne transmission and “the evidence that it’s a significant mode of transmission is negligible”, with small viral particles “rapidly dispersed” after being exhaled.
The WHO issued the statement after 291 scientists in 32 countries signed a letter urging the global body to update its guidance on how the respiratory disease passes between people, after studies found floating virus particles could infect people who breathe them in.
Director of the WHO Collaborating Centre for Air Quality at the Queensland University of Technology, Professor Lidia Morawska, who wrote the letter, told The Age and The Sydney Morning Herald “outdated” medical views about how viruses spread had been holding back the adoption of masks in Australia.
“This dogma was built on research conducted in the 30s and 40s,” Professor Morawska said.
She said more recent research had shown a single infectious person could spread the virus through an entire unventilated room.
“That made the case for masks clear,” she said.
Dr Coatsworth said the expert body would continue to maintain a “watching brief” on the issue, but there was “no proposed change to the recommendations at the moment” and research on airborne transmission should be treated with caution.
“We know that you can find virus in the air around someone who is infected, but those tests are largely done in laboratory conditions,” he said.
“We do not necessarily know the implication of that and how readily that means the virus is going to be spread beyond the 1.5 metres that we recommend people to socially distance … The basic reproductive number is only 2.5 and that is more consistent with viruses that the primary mode of spread is contact and droplets.”
Infectious disease expert Raina MacIntyre, head of the biosecurity research program at the University of NSW’s Kirby Institute, said community face mask use was “a sensible strategy” in addition to social distancing.
“We need clear, positive and simple messaging, not half-hearted messages accompanied by a long litany of warnings about the dangers of face masks,” Professor MacIntyre said.
“The proclamation that SARS-CoV-2 is spread by droplets and contact only is not based on any good evidence – it is speculation.”
The Australia Medical Association on Wednesday urged Melbourne residents to wear masks if they left their homes during lockdown, particularly on public transport.
If physical distancing cannot be guaranteed, AMA President Tony Bartone said wearing masks might now be a good idea. “This is especially the case in those suburbs where we know community transmission is high,” he said.
But he said masks should not be regarded as “a silver bullet, particularly when not worn correctly”, and “isolation, physical distancing, and regularly washing your hands” were more effective at reducing transmission.
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Dana is health and industrial relations reporter for The Sydney Morning Herald and The Age.
Liam is The Age and Sydney Morning Herald’s science reporter