More than 90% vaccination possible, but alternative is bleak

Pfizer and its German partner BioNTech SE say they have so far found no serious safety concerns...
Vaccinating 90 per cent of our total population is possible, fresh modelling has found - and it could spare thousands of Covid-19 deaths and life unencumbered by constant lockdowns. Photo: Reuters
It's possible to vaccinate 90 per cent of our total population, fresh modelling released by Prime Minister Jacinda Ardern has found - something that could spare thousands of Covid-19 deaths and life unencumbered by constant lockdowns.

But the modelling, carried out by Te Pūnaha Matatini researchers, also suggests that vaccinations alone won't be enough to keep the highly contagious virus at bay, with public health measures still needed.

With the Pfizer vaccine expected to be approved soon for use in children aged five to 11, the modelling found this could potentially lift coverage as high as 90 per cent – the threshold at the centre of a new campaign by The New Zealand Herald.

It painted a much more optimistic outcome than earlier modelling by the same researchers which found 97 per cent of Kiwis would need both Pfizer jabs for New Zealand to withstand the Delta variant without the need for harder measures like lockdown.

But that was before the vaccine became available to young people over 12 - and before it could be assumed the shot would be approved for children older than five years old.

The modelling, however, still came with some troubling figures around what could eventuate if vaccine uptake - around 40 per cent of eligible people have so far received both doses, and 35 per cent one dose only - fell lower than 90 per cent.

Even at 80 per cent coverage of over 5s, and assuming only baseline public health measures and limited test-trace-isolate-quarantine, the modelling carried a median estimate of 1.1 million infections, around 60,000 hospitalisations and nearly 7000 deaths - all within a period of just a year.

At 70 per cent coverage, the corresponding figures were higher still at 1.7 million infections, around 110,000 hospitalisations, more than 13,000 deaths, and nearly 18,000 hospital beds occupied at the peak.

At 90 per cent, however, the modelling pointed to 171,000 infections - but only around 6000 hospitalisations, just over 600 deaths, and 438 beds occupied at the peak.

"The modelling results show the importance of New Zealanders achieving the highest vaccination coverage we possibly can," modeller Dr Rachelle Binny said.

"If nearly every New Zealander gets the vaccine, we could avoid the need for strict Alert Level 3-4 restrictions."

At the same time, the increased threat posed by the Delta variant has become clearer with recent data showing it is both more infectious and more likely to cause severe illness.

"The modelling tells us that for Delta, population immunity is still out of reach by vaccination alone," Hendy said.

In an 80 per cent scenario, higher alert levels would still be needed to control transmission - but that need was reduced with higher coverage rates.

"If we can get vaccination rates well over 90 per cent of over twelves or into the 5-11 age group, then the virus can be controlled with more sustainable public health measures," modeller Professor Michael Plank said.

"Testing, contact tracing and wearing face masks will lead to considerably better health outcomes."

Binny described the alternative as "bleak".

"Failing to reach these high levels of vaccination would mean we will need to keep relying on lockdowns and tight border restrictions to avoid thousands of fatalities," she said.

"This could cripple our healthcare system, and Māori and Pacific communities would bear the brunt of this health burden."

The model provided a rough guide to the benefits of high vaccination rates at the population level, not a detailed roadmap for reopening.

The results ultimately showed that, if we want to see an end to lockdowns, we need to strive for very high vaccine coverage.

It also showed how essential it was to achieve high vaccination rates not just nationally, but also in specific communities including Māori and Pasifika populations.

"The results here demonstrate the considerable benefits of achieving high vaccination coverage in the coming months," Hendy said.

"The message from the modelling is that Covid-19 is going to continue to disrupt our lives for some time yet, but that we can minimise that disruption by ensuring we all get vaccinated."

"There is no magic threshold for vaccination coverage. But the higher the coverage, the less restrictions we will need in coming years.

"And most importantly, we need every community to be well covered by vaccination. We can't afford to leave anyone behind."

Over the coming weeks and months, the modellers expected to release a more detailed look at what measures might work best in the community and at the border.

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