PM Jacinda Ardern with Dr Shaun Hendy beaming into the Beehive Theatrette at yesterday's Covid media conference

The Government’s release yesterday of modelling to show likely Covid deaths at various vaccination rates may owe more to politics than pure mathematics.

The release seemed designed to scare people into getting a vaccination.

But in doing that, the Prime Minister has carefully cherry-picked the figures from the mathematical modellers.

The central finding was that at an 80 per cent vaccination rate of people aged over 12, there would be 7004 deaths a year from Covid.

But though that was highlighted in the media release, drilling into the tables of data supplied with it presented another more optimistic scenario.

In fact, at 80 per cent, vaccination rates deaths might be half the figure in the press release, (down to 2560) and at 85 per cent could drop to 191.

The data presented by Professor Shaun Hendy from the University of Auckland’s Te Punaha Martini Centre offers a range of scenarios according to different vaccination rates and public health responses.

There are also three different streams in the model according to Vaccine Effectiveness.

That is a widely used medical term to compare the rates of disease between vaccinated and unvaccinated people.

The 7004 deaths came from a stream that assumed that the Pfizer vaccine is only on the mid-point of a 0 – 100 vaccine effectiveness scale.

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But both the Ministry of health and the United States Centres for Disease Control rate the Pfizer vaccine as “Highly Effective.”

If that stream in Hendy’s model is followed, then the deaths when 80 per cent of people aged over 12 are vaccinated decline to 2560.

And if  80 per cent of everybody over five were to be vaccinated, the figure would be 94.

This is a table showing Hendy’s forecasts for deaths at various vaccination for people over 12 and vaccine effectiveness rates.

Covid death projections by vaccination rate

VaccinatedHigh VEMedium VELow VE
70%95231327117947
75%61511000114820
80%2560700411870
85%19143149126
90%2215576623
95%221234407

What is clear from the modelling — and this was what the Prime Minister wanted to emphasise yesterday – was that as vaccination rates go up, deaths dramatically decline.

Using the “Highly Effective” vaccine rating, if 85 per cent of the population over 12 were vaccinated, deaths would drop to 191. That is less than the flu.

A 2017 Otago University study found that flu was killing about 500 New Zealanders a year.

But New Zealand’s vaccination rate is slowing.

On Wednesday last week, there were 62,782 vaccinations; Wednesday this week, only 49,667 jabs. Even that number was down on the previous day (Tuesday) when there were 53 721 injections.

“What we know is that actually as a vaccination campaign, we have outstripped many other countries we would compare ourselves to,” Ardern said yesterday.

“But what every country has experienced is a point where you reach a certain rate, and ours has been higher than most, where it gets a little bit harder.

The point at which Auckland, for instance, could hit 90 per cent is anywhere between a couple of weeks or a month, depending on people’s willingness to come forward.

And that’s where it’s going to take all of us.

“It’s not about just going out and applying pressure to people or saying, get vaccinated.

“We need conversations.

“We need to talk about why it’s important.

“And that’s what this is about today.”

Yesterday is not the first time Ardern has had dire death projection modelling from Hendy.

In March last year, he forecast there would be 80,000 deaths if the Government took no action against Covid.

His model assumed 20 “seed cases” and a transmission rate of 2.5 (that is, one infected person would infect another 2.5).

That modelling was persuasive in getting Ardern to introduce the first lockdown last year. She sees it as an insp[iration for how yesterday’s modelling from Hendy might impact.

“I got modelling much, much worse than this much, much more dire than this at the beginning of Covid,” she said.

“And we then, as a result of it, designed a plan so that none of that came to fruition.

“And we have the ability to do that again.”

However, this time around, the public health “tools” the Prime Minister is proposing are less severe than lockdowns.

She said they would be a mixture of things “like isolating cases, improved ventilation in public spaces, strategic use of masks, vaccine certificates, and an approach at our border that means we try and catch cases but won’t necessarily mean that full 14 days of quarantine as we know it now.”

But she is not ruling lockdowns out.

“Essentially, at very high levels of vaccine, we can take level 4 out of the toolbox and instead set it aside while vaccines continue to be as effective against variants as they have been today,” she said.

There is a question, once most people are vaccinated, about whether the vaccinated should mix with the unvaccinated.

In Australia, Solomon Lew, the billionaire owner of shopping chains like just jeans, Portmans and Jacquie E, said yesterday that he anted mall owners to admit only people who had been vaccinated.

This has raised the question of whether governments should allow businesses to mandate vaccinations for workers and customers.

Ardern seems opposed.

“We haven’t put in place blanket mandates across the board for vaccination in New Zealand, and we never have,” she said.

“But there will be some more nuanced scenarios, and we keep working out some of that guidance to support employers with those decisions.”

However, she did concede there might be some areas where some sort of mandatory requirement for vaccination might need to be imposed.“

“There have been some areas where we’ve said, actually, because of the risk to individuals, we do think that it’s incumbent on us to go a little further and require vaccines,” she said.

“In other workplaces, very much employers will be having conversations with employees, and what you have seen here today is some discussion over some tools, like, for instance, vaccine certificates, and that’s a very live debate for us because it doesn’t preclude you from engaging in life, but it says if there are certain things you want to do safely, maybe they’re a legitimate tool.

“So those are things we’re discussing and debating.”

The Ministry of Health is developing a vaccine certificate for New Zealand, but Australians already have them as part of their Medicare digital apps.

All of this now depends on the vaccination rate.

That is now the Prime Minister’s big challenge.