Covid 19 Omicron outbreak: Derek Cheng - Why borders could fully reopen before winter

ANALYSIS:

It's a no-brainer for the Government to accelerate its timeline to open the borders, given the Omicron peak will hit in coming weeks - perhaps within two weeks.

It follows the predictable scrapping of isolation for fully vaccinated and negative-tested Kiwis.

It was already obvious, with tens of thousands of new cases a day, that the level of risk from new cases at the border paled in comparison with the risk of new cases in the community.

The most recent modelling, revealed yesterday by Prime Minister Jacinda Ardern, estimated an expected 100 to 425 additional cases a week flying in from overseas and strolling into the community following an isolation period. This assumed 65 per cent of cases at the border still being Covid-positive by the time their seven-day period was over.

With no isolation, then, those estimates rise to between 150 and 654 additional cases a week - still a drop in the ocean of the 100,000-odd new community cases per week.

Opening the borders to non-Kiwis - currently scheduled from July for those flying from Australia, and from October for the rest of the world - would see about 10,000 new arrivals on average every day, if they flocked to New Zealand in pre-pandemic numbers.

Epidemiologist Professor Sir David Skegg made it clear that they would present a significant, additional risk if they arrived in New Zealand tomorrow.

Prime Minister Jacinda Ardern, joined by Professor David Skegg via audio-visual link, announcing an end to MIQ and isolation for fully vaccinated overseas arrivals. Photo / Mark Mitchell

But that risk would shrink massively after the Omicron peak has come and gone.

"Once that's happened, there will be much higher levels of immunity from prior infection in the community," said Covid-19 modeller Professor Michael Plank.

"Once you've peaked and are on the other side of the wave, overseas cases are not so important because they're not going to contribute significantly to any resurgence."

They are still important if any of them are infected with a new variant, so it remains vital to have on-arrival tests, and to genomically sequence all positive results.

But without a new variant, a faster timeline for opening the border is inevitable. It could happen before winter, if the health system had enough buffer for not only Covid, but the winter flu season.

Reunions at the airport will become more frequent as the borders open up more in coming months following the Omicron peak. Photo / Bertt Phibbs

By then, the usefulness of the vaccine pass will also be on borrowed time.

It arguably is already, given the signs that two doses are far less effective against Omicron than three. UK data suggests only up to 10 per cent protection against symptomatic disease five to six months after a second jab, jumping to 60 to 75 per cent after a third dose.

That means the pass would only offer meaningful protection to people in a bar or cafe or gym if it required three doses.

Said Skegg: "The word booster implies an optional extra. It's not. To be fully protected, you need three doses."

Ardern has said, reasonably, that some vaccine mandates will remain including in healthcare settings, but the Government is yet to make any decisions on a three-dose pass.

She will be mindful of the High Court decision that the mandates for police and the Defence Force were unjustified because the health benefits weren't enough.

That would also likely be the case for the two-dose vaccine pass, once Peak Omicron has subsided.

When that will be is best indicated by a consistent drop in daily hospitalisations.

The peak could hit in mid-March or even earlier, Ardern said, as Omicron is spreading faster than expected. The next weeks will be bumpy.

So far, Plank said, the outbreak seemed to be tracking most closely to the model that assumed medium levels of transmission and 90 per cent booster coverage for eligible people.

That could see an estimated 2.4 million infections, including 626,000 cases, 19,300 hospitalisations and 840 deaths. The seven-day rolling average of daily cases could peak at 17,700.

Plank added that the number of deaths could be lower because the ages of the infected were younger than what the model had assumed, and the younger you are, the less likely Covid will kill you, all other things being equal.

MIQ will still serve a purpose in the new normal by housing the unvaccinated flying in from overseas. According to the Ministry of Health, the current outbreak indicates that the unvaccinated are four times more likely to end up in hospital.

A new variant could see the new normal upturned, yet again, if it were more infectious and virulent than Omicron. That could see border defences return to protect New Zealand's comparatively poorly resourced health sector.

Two years after the first Covid-19 case in New Zealand, it seems a fitting reminder that the pandemic is far from over, and will continue to be as fast-moving and unpredictable as ever.