The Government's new suppression strategy risks overwhelming the health system if the virus gets into under-vaccinated communities or if overworked public health officials can't keep up, Marc Daalder reports.

ANALYSIS: The Government has called time on elimination, 18 months and four days after Ashley Bloomfield embraced the strategy at a select committee hearing held under level 4 lockdown conditions.

As she announced a roadmap for Auckland's path out of lockdown on Monday, Prime Minister Jacinda Ardern said Covid-19 cases would be present in the community but kept to low levels.

What I'm indicating is that in spite of not having reached zero, that doesn't mean that we are not able to successfully continue our work to keep people safe in the long-term and take an aggressive approach to Covid, she said.

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On Monday, Prime Minister Jacinda Ardern announced a three-step road map for Aucklands path out of lockdown.

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Vaccinations will help us. Our contact tracing will continue to play a role. We'll still isolate every case. And in the future, public health measures will still be part of the mix as well.

Experts say New Zealanders should prepare for the presence of Covid-19 in the community under the new approach, even if the Government is striving to keep cases down and the health system from being overwhelmed.

This relaxing of restrictions will see more spread and more Covid cases in the community over the coming weeks, Te Pnaha Matatini Covid-19 modeller Shaun Hendy said.

This isn't just the case in Auckland, either. Hendy's fellow modeller, University of Canterbury mathematics professor Michael Plank, said we should expect to see the virus outside of the city.

The Auckland boundary will remain in place for now. But if, as is likely, case numbers continue to grow, it will become progressively harder to keep the outbreak contained to Auckland, he said.

The rest of New Zealand should prepare for the inevitability of community transmission. Regions that experience outbreaks may need to be put under restrictions like those in Auckland.

Ricky Wilson/Stuff

Te Pnaha Matatini Covid-19 modeller Shaun Hendy. (File photo)

Abandoning elimination does not mean the Government will wave the white flag and surrender to the virus. Auckland is still at level 3 and the initial step in loosening restrictions will add relatively little risk of onward transmission.

Ardern was at pains to emphasise that the strategy won't look that different from elimination. We will still rely on contact tracing, testing, masking and other public health measures, as well as tougher restrictions like lockdowns while vaccination rates remain low, to keep transmission low.

But the mere fact that the end goal is different that the Government is now satisfied with low levels of community transmission rather than none at all raises new and potent risks.

Experts have previously said a suppression strategy like that adopted by the Government on Monday would see restrictions in place for weeks to months. University of Otago epidemiologist Michael Baker highlighted that again on Monday evening.

Step 1 is pretty much Level 3 and Steps 2 and 3 are versions of level 2, he said.

When could Auckland move to those Level 2-style restrictions?

You need to see that case numbers are not increasing. I don't think you could ever expect that we'd be moving out of Step 1 anytime soon. Just from what we know of the experience of Victoria and New South Wales and what we've seen here.

Auckland's exit strategy is now vaccination rates, with Ardern targeting 90 per cent of the eligible population double dosed. But only 84 per cent have had their first dose thus far. Even if the remaining 6 per cent (around 86,000 people) went out and got jabbed today, it would still be six weeks before their second dose and another two weeks before they're considered fully protected. Clearly, suppression means Auckland is in lockdown for the long haul.

In the meantime, the Government's goal is to keep transmission low enough that the health system isn't overwhelmed. While successful elimination looked like reaching zero cases and returning to the freedoms of level 1, successful suppression sets a much lower bar of ensuring our hospitals are not overflowing with Covid-19 patients although the consequences of failing to achieve that bar are much more serious with suppression than with elimination.

There are three major and interconnected risks to the Government's ability to keep the health system standing.

The first is the outbreak taking off in under-vaccinated populations. Schools are tentatively slated to reopen from October 18, but children under 12 aren't eligible to be vaccinated. While children pose relatively little threat to one another, they're more likely to be infected by their adult teachers and other school staff members. Currently, however, teachers aren't required to be vaccinated, masks aren't mandated for students in schools and New Zealand's schools have notoriously poor ventilation.

We need to immediately take steps to ensure that schools open in the safest way possible, Jin Russell, a developmental paediatrician at the University of Auckland, said.

One of the best ways we can protect children and re-open schools safely is to aim for 100 per cent of teachers and staff, and 100 per cent of eligible students, to be vaccinated. Overseas experience also shows that by implementing a suite of measures including improving ventilation, taking activities outside, masking, and other measures, schools can drive the risk of Covid-19 transmission to very low levels.

Children aren't the only under-vaccinated group, however. Mori and Pasifika vaccination rates have lagged behind those of the general population. In Auckland, fewer than a quarter of Mori were fully vaccinated by last Tuesday.

As of Sunday, nationwide, just 56.7 per cent of Mori and 73 per cent of Pasifika had received a first dose of vaccine, compared with 80.3 per cent of white New Zealanders.

Unvaccinated people are also likely to be clustered into the same communities, raising the risk of an outbreak. All of the 11 district and city council areas with the greatest proportion of Mori residents are also among the 15 least vaccinated council areas. More than a third of the eligible population in 11 council areas is unvaccinated and populations in nine of these 11 are more than 16 per cent Mori.

These communities are exposed to outbreaks of the virus. If suppression slips up in ptiki district for example, where the population is 44 per cent Mori and where 38.3 per cent of the eligible population is unvaccinated, the outcomes could be grievous.

Jin Russell/Supplied

Jin Russell, a developmental paediatrician at the University of Auckland. (File photo)

That brings up the second risk to the success of the suppression strategy: The capacity in our public health system to ensure suppression doesn't slip up.

New Zealand's public health officials have spent 18 months testing for Covid-19, tracing the contacts of new cases and planning for new outbreaks, all while chronically underfunded and unable to carry out their non-Covid-19-related public health work.

While they were already gearing up to manage a greater burden of new cases after the country reopens next year, an expected period of rest and preparation has now been overrun by the current Delta outbreak. It took the Government six days at the start of the outbreak to start re-tasking other public servants with contact tracing, at which stage less than two thirds of more than 20,000 known contacts had even received a phone call from tracers.

Despite four critical reviews urging the Government to resource the contact tracing system to be able to deal with the contacts of up to 1000 cases a day, the Ministry of Health never did so. Now, it is not impossible that we do see case numbers in the hundreds, even though that could overwhelm our current tracers.

New Zealand would struggle to maintain high system performance of contact tracing for a prolonged period with 100-200 cases per day, one such review, commissioned by the Government, warned after the February outbreak. And this didn't account for the transmissibility of the Delta variant which we are now dealing with.

If contact tracing collapses, then suppression at our current vaccination rates without harsh lockdowns becomes almost impossible. The response is now contingent on the most crucial part of our public health system which has been consistently ignored and under-resourced over the course of the pandemic.

The third risk is that we might not know our contact tracing has failed and the health system is threatened until it is too late.

The suppression strategy is the result of a March 2020 modelling paper from the Imperial College London, which found that mitigating the virus (flattening the curve) would see hundreds of thousands of deaths in places like the United Kingdom or United States because hospitals would be unable to care for all of the grievously ill patients.

Suppression involved stamping the virus to extremely low levels and then progressively loosening restrictions. Inevitably, the virus would resurge and when that renewed outbreak began to threaten the capacity of the health system, new restrictions would be imposed.

In the United Kingdom, the trigger for a new lockdown was to be 100 cases in ICU in a week. The UK's health system had significantly more capacity, but these new cases in ICU would be the result of infections that happened weeks ago. Even after locking down, the modelling showed, ICU admissions would continue to rise, perhaps doubling or tripling above the 100-patient threshold, but not overwhelming the hospital system.

A similar concept may be used with the new roadmap for Auckland, which is set to be reviewed on a weekly basis to discern how the virus situation has responded to each loosening of restrictions. The problem for New Zealand is that we have so little capacity in our health system that we will hit our trigger point with just a handful of ICU cases. By the time an obvious trend starts to emerge, it could be too late to stop ICU capacity from being exceeded.

We'll have to really look at the trend very carefully and if we see signs it's going up, we may have to revisit what we do with these levels or stages, Baker said.

That's backed up by the view of Te Pnaha Matatini researcher Dion O'Neale.

One of the factors that makes outbreaks so difficult to control is the fact that often by the time we know we are on a trajectory of sharply growing case numbers we may already be past the point where interventions like contact tracing or quarantine facilities are able to catch up, he said.

This is because there is a delay between when people become infected or infectious and when we are likely to become aware of them.

In other words, once cases in ICU start to rise, we must immediately respond.

That could even include strengthening the restrictions in place in Auckland or wherever else the virus ends up, both Baker and Plank said.

It will be crucial to remain adaptable and responsive to changes in the number of cases and the healthcare demand they will generate. It may yet be necessary to adjust or tighten restrictions to prevent cases spiralling out of control, Plank said.

The Australian state of Victoria has gone from around 20 cases per day to 1500 in just 6 weeks, and there are currently 96 Covid patients in ICU. This could happen here and it would put immense pressure on our hospitals.

Up until now, New Zealand has enjoyed the benefits of no widespread community transmission of Covid-19 something nearly unique in the world. While that may never have been sustainable in the long-term once the borders reopened, the opportunity to cleanly end elimination has been taken out of our hands. Instead, we are messily transitioning to a suppression strategy while vaccination rates remain too low to, on their own, prevent hospitals from being overwhelmed with Covid-19 patients.

When speaking to Newsroom about the Imperial College London paper in March 2020, Baker issued a prescient warning about the burden of the suppression strategy.

Its one thing to hear about it and see it happening at a distance. Its like watching a Netflix series from overseas, but actually, that will be us if we dont contain it, he said at the time.

Its a new way of living thats pretty foreign. Its pretty obvious that no one alive today has seen a pandemic like this.

After 18 months of keeping it at bay, that new way of living has now arrived on New Zealand's shores at last.

Originally posted here:

Covid-19: 'Prepare for the inevitability of community transmission' - Stuff.co.nz