COVID-19: New Delta modelling does not account for other wraparound protections, blanket vaccination coverage not the only way - Graham Le Gros

A new report has put forward a stark projection of what New Zealand's future could look like with COVID-19, even with high rates of vaccination - but a leading immunologist says it's important to remember the modelling is just a prediction, and a number of factors are not accounted for.

New data from Te Pūnaha Matatini, unveiled on Thursday, suggests that with moderate public health measures in place, there would be roughly 60,000 hospitalisations and 7000 deaths per year due to COVID-19 in New Zealand - even with 80 percent of the population fully vaccinated. 

Auckland University physicist Professor Shaun Hendy, a disease modeller, says a vaccination rate of "well over" 90 percent, either of those aged 12 and over or those aged five and over, would help to control the highly infectious Delta variant - but a suite of "moderate" and sustainable measures, such as mask use, would also need to be maintained. 

The data is based on the assumption that one COVID-positive person will arrive in New Zealand each day when the borders are eventually reopened to the world.

The report does indicate it's possible to vaccinate 90 percent of the population against COVID-19, which would provide a much greater level of protection against the virus. At this rate, the researchers say stay-at-home orders, such as alert levels 3 and 4, would no longer be required - and with more than 90 percent of the population inoculated, the data suggests there would be around 500 hospitalisations and 50 deaths per year.

But immunologist Graham Le Gros says New Zealanders need to remember these projections are just that - projections. The figures are estimates based on the data that is currently available, but are not set in stone - and do not account for a number of factors.

"[Professor Hendy] doesn't really know how the virus would [act] in a vaccinated community - it's a projection. It's still just a model, and it gives us an idea of what it could look like if we don't vaccinate to that level," Le Gros told The AM Show on Friday morning. 

"It is over the [course of] a year - it doesn't take into account a lockdown being put on top of that, or if we do booster vaccinations mid-next year, which could really change the game as well.

"At the moment, that's all we can say based on how the virus has performed overseas with vaccinated people  - this is what it could look like."

Le Gros pointed to Singapore, a nation with a slightly larger population (around 5.7 million) and a high rate of vaccination that is now trying to live with COVID-19. According to its Ministry of Health, 82 percent of Singapore's population was fully vaccinated as of September 22. The country, which has reported more than 81,000 cases of the virus since the beginning of the pandemic, has recorded only 68 deaths - 27 of which have occurred since restrictions were eased on June 21.

COVID-19: New Delta modelling does not account for other wraparound protections, blanket vaccination coverage not the only way - Graham Le Gros
Photo credit: Worldometers

But cases of the Delta variant are now rapidly on the rise in Singapore, with the government closely monitoring hospital capacity. As of September 23, there are 1120 cases in hospital, with 163 requiring oxygen supplementation and 23 in the ICU.

"As an immunologist, I think we can't really tell how the immune system - the population's protective immunity - is going to behave with the virus if it spreads here in New Zealand. We move around in different ways - we're not on the mass transport [systems] you see in Singapore, for instance," Le Gros said.

"There the virus is much more intimate with the people, whereas here, we do spread out and in summer, it may be a different course of infection. But we'll just see."

Graham Le Gros.
Graham Le Gros. Photo credit: Supplied

The report has also prompted debate around the specifics of the vaccination rate, such as whether the 90 percent coverage also includes children under the age of 12. Medsafe has yet to approve the vaccine for use in children aged five to 11 - currently, only New Zealanders aged 12 and over are eligible for the jab. 

On Thursday, Associate Health Minister Peeni Henare also admitted he would "have reservations" about reopening the borders if a high vaccination rate had not been achieved across all populations - suggesting 90 percent should be a baseline for every group in New Zealand, including rural, Māori and Pacific communities. 

Preliminary research has indicated the vaccine is safe for children aged five to 11, Le Gros said. He urged parents to take the opportunity should it become available.

"It looks like you can go all the way down to five-year-olds and you get a good immune response, so the vaccine really works. [Researchers] weren't so concerned about the adverse reactions because we know 220 million people have received this vaccine - it is so safe," he said. "So it looks as though we're in a very strong position to, if it was possible, get up to 90 percent.

"We've been privileged in New Zealand as we haven't really seen the effects of this virus… People are always wary of what you put into your kids, but I think this virus is serious enough. Parents would be well-advised… We just want to keep it away from our young people and our old people - and our middle-aged people."

Auckland University's Siouxsie Wiles, an infectious disease expert, agrees, telling Newshub that although trials are ongoing, the preliminary data regarding vaccine safety and efficacy in children is looking "very promising".

"Medsafe wants all of the data. No one wants to see a vaccine used where that approval has been rushed through, people want the guarantee it has been looked at properly, and that's going to take a bit of time. Meanwhile everyone who can be vaccinated, should be," Wiles told Newshub on Thursday.

"The reality is no country at the moment can get a very high vaccination rate because no vaccine has been approved for children."

Regarding the idea that each group in New Zealand would need to achieve a vaccination rate of 90 percent, Le Gros said blanket coverage is not the only way forward - and the new modelling does not account for other means of protection, such as booster shots or additional drugs. For example, earlier this month Pharmac widened its funded access to tocilizumab, an immunosuppressive drug used mainly to treat arthritis, to treat moderate to severe cases of COVID-19. Studies have shown tocilizumab may help hospitalised patients by reducing the severity of their infection. 

"Māori and Pacific we believe are quite susceptible to more serious infections if they get COVID-19, but there are other ways of mitigating or preventing people from being sick. There are drugs, there's a thing called antibody therapy... we can actually put some wraparounds for some targeted minorities with booster shots," Le Gros said.

"You can do a number of things to really protect your most vulnerable in the community, you don't actually have to have the blanket vaccination across all the populations. These kinds of nuanced ways of dealing with it will come in the new year. 

"Shaun Hendy's model gives a projection for the whole year if we just sit on our hands and do nothing, but that's not going to happen. [It's about a] target, modified, super-boost and actually put some drugs around people who… are vulnerable [sic]."

Le Gros reiterated the 90 percent target is possible, noting that New Zealand does not have the same issues as other nations currently struggling to boost their uptake of the vaccine, such as a lack of education or divisive media. 

"I think we can get there. We have a well-educated population who understand the risks, despite the crazy anti-vaccinators, which are a very small minority... and we've got great media who engage so well on this issue, we don't have the same issues in the States or elsewhere."

Wiles echoed this sentiment, telling Newshub it's imperative people continue to talk to their whānau and friends to ensure they are accessing the right information. If people are guided towards official and accurate information and are encouraged by those around them, a high rate of vaccination is achievable, she says. 

"There's those people who refuse to get vaccinated for a number of reasons, such as they've fallen for misinformation, or there's those who still have questions. It's absolutely fine to have questions, but we need to be answering them… it's the job of everyone, really, to make sure they're having those conversations about why they're getting vaccinated… we do this not just for ourselves, we do this for everyone," she said.

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