16 Oct 2023

Covid: Still here, still deadly

From The Detail, 5:00 am on 16 October 2023

Unless someone high profile gets it, most of us aren't thinking about the dangers of catching Covid-19 now. We should be – it's our country's biggest infectious disease killer, twice as deadly as influenza.

University of Otago epidemiologist Professor Michael Baker

University of Otago epidemiologist Professor Michael Baker Photo: University of Otago Wellington / Luke Pilkinton-Ching​

Every week we see thousands of cases, hundreds lying in hospital beds, and around 20 deaths. 

Sorry to say it, but Covid-19 is still alive and kicking. 

"It's a bit like an unwelcome guest that no one wants to talk about, but it hasn't gone away, that's for sure,'' University of Otago epidemiologist Professor Michael Baker tells The Detail

"It's our number one infectious disease threat... it's really displaced influenza as our biggest single infectious disease killer."

And Baker warns the number of reported cases are probably well behind what's actually out there.

"[There are] 3,500 or so reported cases every week, but we know that will be at best 50 per cent of the cases in the community... maybe less than that... so we're still looking at about 10,000 cases probably a week at least."

Baker says reporting has dropped off for several reasons, such as there no longer being mandatory self-isolation and the Covid-19 leave support scheme ending, which helped pay employees who had to isolate.

And wastewater results are showing an interesting, if not slightly concerning, trend.

"We're seeing a rise at the moment, a relatively small rise, in the detection of this virus in wastewater, unlike the continuing decline we're seeing in self-reported cases, and this does seem to date to the period when we removed the subsidy for self-isolation, and that coincided with when we removed mandatory self-isolation."

Baker says the virus hasn't stopped evolving. He led the publication of a recent paper in the New Zealand Medical Journal, co-authored by 16 academic experts, which calls for careful mitigation strategies.

"Mitigation is not a 'do-nothing' approach. You do a selection of things to try and minimise the harms caused by an infection."

He talks about being up-to-date with vaccinations, staying at home and self-isolating if you're sick, and putting on masks in crowded indoor environments like public transport.

Also in this episode of The Detail, associate professor Helen Petousis-Harris, a vaccinologist at the University of Auckland, talks about vaccine developments.

She says current vaccines are effective at protecting against serious disease, but not so much the asymptomatic or mild infections.

"They started off with a hiss and roar because they were quite well-matched to those circulating variants," she says.

"As that shifted, the ability to prevent initial infection in the first place – that was what you saw wane first, and then the ability to prevent mild disease, whereas you see that protection against more severe disease holding."

She says there's a lot of work going on to get better vaccine solutions. 

"These are things like intranasal vaccines – so vaccines you sniff – or skin patches... you want them in your upper respiratory tract to catch that virus as soon as it appears. So we're likely to see that sort of thing coming along, hopefully near rather than far future now.

"And that of course has got that spillover for other respiratory infections as well. Covid's not the only game in town. Influenza causes us grief every year, along with other respiratory viruses."

Petousis-Harris says there could be combination vaccines – attacking several viruses in one shot – in coming years.

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