Virus expert warns Covid lessons ‘no longer apply’ for Delta strain

A virus expert explains why the Delta strain has torn up the Covid-19 rule book – and reveals one thing NSW authorities urgently need to do.

Top virus expert Professor Mary-Louise McLaws says the lessons learned in battling Covid over the past 18 months “no longer apply” when tackling the Delta strain – and called on authorities to vaccinate Sydney’s 20 to 39-year-olds as a matter of urgency.

Prof McLaws, a University of New South Wales epidemiologist and member of the World Health Organisation’s (WHO) Covid-19 advisory panel, made the worrying statements during an interview on The Sunday Project, revealing WHO would soon hold a “special meeting” to share information about Delta.

“Across the world, particularly from the UK and US, we are learning that the lessons we learned previously about the different strains no longer apply,” she said.

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Professor McLaws: ‘The lessons we learned no longer apply.’

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“Certainly, what we’ve heard from the UK is that Delta means people are twice as likely to be hospitalised, and that you don’t need 15 minutes of exposure within 1.5m [to contract the virus]. All of that is thrown out.

“The other thing we thought worked was that young people are not at risk – all of that seems to be wrong. This particular virus develops about 1000 times more virus load in patients, so they are highly infectious. We’ve also learned the incubation period is two days shorter than we ever thought.”

Given these disturbing new features of the virus, Prof McLaws said authorities must move to protect the largely unvaccinated under-40s population in Sydney, where the Delta strain is currently spreading, particularly across the city’s southwest.

“I’ve been pushing, but obviously not hard enough, that 20 to 39-year-olds need Pfizer right now. Not with a distance of many weeks [between doses] – 21 days between dose one and dose two, because you don’t get that maximum protection until two weeks after the second dose, and you don’t get a lot of protection, except from death, from just one dose. You need two doses, and you need them at 21 days apart,” she said.

But Prof McLaws said that, where Pfizer isn’t readily available, she would recommend AstraZeneca be used to reduce “infection and transmission”.

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Prof McLaws encouraged Sydneysiders to wear masks outdoors.

Prof McLaws also repeated a sentiment she’d expressed recently on The Project, strongly encouraging those in Sydney to wear masks even when outdoors.

“When there’s circulating virus, we absolutely need to wear a mask outside. I still see people going for a walk without a mask, and then coming into shopping areas without a mask. Please, you’re placing yourself at risk of breathing in somebody else’s exhaled particles. Please wear your mask,” she said.

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McLaws had sympathy for those who attended Saturday’s protest: ‘We need to look after them.’ Picture: NCA NewsWire/Flavio Brancaleone

And Prof McLaws said she was concerned about the likelihood of cases arising from Saturday’s Sydney anti-lockdown protest – but she also said it was important not to dismiss the anger and frustrations of those protesting.

“What I’d say to the authorities is, you need to bring everybody on board and not misunderstand the anxiety of these people who are probably feeling very stressed financially. We do need to look after them … they need to reassess how they’re going to engage these people who are very, very stressed.”