16 Sep 2021

Health experts say talk of vaccination targets unhelpful

12:03 pm on 16 September 2021

Countries around the world are starting to imagine a future living with Covid-19 as vaccination benchmarks are reached.

Hundreds of people have begun arriving at a mass vaccination event for essential workers at the TSB Stadium in New Plymouth this morning. The Taranaki DHB is hoping to give shots to almost 7000 people at clinics in New Plymouth and Hāwera over the weekend.

A mass vaccination event at the TSB Stadium in New Plymouth last month. Photo: RNZ / Robin Martin

But is there a magic number and when will New Zealand reach it?

For critics of New Zealand's pandemic response, Denmark is the shiny, new poster-child.

The Scandinavian country has now lifted restrictions after vaccination rates passed 80 percent of those 12 and over.

The two countries have their similarities - population size for one.

Denmark even possessed the altruism to provide 500,000 doses of the Pfizer vaccine so New Zealand's vaccine rollout can steam ahead at the pace which previously threatened to see us run out of the vaccine - or needing us to "dampen down the demand" in government terms.

Based on current vaccination rates it is possible, and maybe even plausible, that New Zealand can reach 80 percent coverage of our eligible population this year.

So what will that mean?

Evolutionary virologist Dr Jemma Geoghegan, a senior lecturer at the University of Otago, said the idea of vaccine benchmarks had to be treated with caution.

"The data out of the UK suggests that 95 percent of the population have some level of immunity to the virus, either through vaccination or past infection. They're still experiencing around 150 deaths a day from this coronavirus and this is during summer."

The British experience might provide clues for how the virus would behave here if restrictions were lifted even after high vaccine coverage.

If the current death rate in the UK was comparable to what New Zealand might expect, it would translate to more than 3500 deaths a year in New Zealand.

That would be more than car crashes, suicides, breast cancer, prostate cancer, melanoma and diabetes - combined.

Denmark had recorded 2600 deaths from Covid-19 and was still seeing daily deaths.

University of Otago virologist Jemma Geoghegan.

Dr Jemma Geoghegan says the idea of vaccine benchmarks must be treated with caution. Photo: University of Otago

"It might be that people overseas have become desensitised to it, because it was at one point a lot worse than it currently is," Dr Geoghegan said.

"If we were coming to the point where we were going to have that many deaths a day, I think it'd be really hard to accept for people in New Zealand."

At current rates the Danes could expect about 1000 deaths a year, and its restrictions had only just lifted.

The other problem in New Zealand was vaccine equity.

Based on the current vaccine equity rates when 80 percent coverage for the general eligible population was reached, only 55 percent of eligible Māori would have had two doses.

Te Rōpū Whakakaupapa Urutā co-leader Dr Sue Crengle said if that disparity persisted throughout the rollout then lifting restrictions at that point would not only be catastrophic for Māori - it would be unethical.

Research from Te Pūnaha Matatini showed a 44-year-old Māori person was at the same risk from Covid-19 as a 65-year-old Pākehā.

The inequity in lifting restrictions would be further exacerbated by the disproportionately young Māori and Pasifika populations, Dr Crengle said.

"In rare circumstances children die from Covid, number one. Number two there's a very rare complication from Covid called Multisystem Inflammatory Disorder, which is very nasty in children - it's very rare but it still happens. And then number three ... about 8 percent of children would go on to get long Covid."

Last week in the UK, Covid deaths rose to their highest rate since March and deaths from all causes were 8.7 percent higher than for the corresponding weeks from 2015 to 2019.

For the week in which the latest data was available, 20 percent of all Covid deaths in the UK occurred in those aged 64 or younger with the youngest victim aged between one and 14.

Professor Nick Wilson

Professor Nick Wilson says until we have a sterilising vaccine we may need to continue with the elimination strategy. Photo: RNZ Insight / John Gerritsen

Such factors were why Otago University public health expert Professor Nick Wilson said we had to be prepared for some restrictions until at least pre-teens could be vaccinated, and potentially beyond.

"Things like long Covid are potentially going to be very serious conditions, there's even some risk they're going to be life-long. So when you're thinking about those sort of things it does mean that the amount of health loss in a society could really mount up."

It was why some changes to behaviour were likely to remain for the foreseeable future, with only the development of a vaccine that provided sterilising immunity allowing for a return to 2019 normality, he said.

"It may be we're in the long haul for keeping the elimination strategy until we have a sterilising vaccine - it's completely effective, like measles vaccine, and you get no transmission. So then you would be able to get to herd immunity with high coverage and you wouldn't need to have other control measures.

"So the world really should be putting an enormous amount of effort in - and it is, we've made some great strides with vaccine technology, but that is the vaccine we want. A completely effective one where there is zero transmission when someone gets exposed."

None of the current crop of vaccines fit that bill.

Wilson said New Zealand was not the only area pursuing an elimination strategy as China, Hong Kong, Taiwan and several Australian states were also going that route.

New Zealand's response had meant not only had it had far fewer Covid deaths than other countries, but its economy had outperformed most of the OECD and the health system was also able to recover well from the lockdown, he said.

Denmark also still had some degree of travel restrictions in place and mask wearing in certain situations, so the situation had been exaggerated, Wilson said.

"They will be having children getting sick with Covid and potentially suffering very long-term consequences," he said.

"I think just like it would have been a mistake to copy Sweden last year, it would be a mistake to blindly copy Denmark at present."

Covid-19 modeller Professor Michael Plank said, simply put, when it came to vaccination rates there was no magic number at present.

"I think we need to aim to get as close to 100 percent as we possibly can. We're not going to get to 100 percent but we should be aiming to get as high as possible and the higher vaccine coverage we get the better position we'll be in, the more options we'll have and the better protected we'll be against the health impacts of Covid-19."

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