9 Nov 2022

New Zealand Covid-19 situation complex and hard to predict - modeller

12:49 pm on 9 November 2022
Collage of two sick people

There were 3912 news cases reported yesterday. Photo: 123rf.com / Composite Image - RNZ

The country's Covid-19 situation is like a big bowl of spaghetti, with a plateau in cases not necessarily telling the whole story, a leading modeller says.

Reported case numbers have remained relatively static over the past two weeks, after initially trending up in mid-October.

Covid-19 Modelling Aotearoa data modeller Dion O'Neale said there were lots of different strands to the situation, with people's behaviour and a number of new variants both playing a part.

That made it hard to predict, to find out which trend would win out.

"Some people have been infected more than once, some people are out there managing to be uninfected, and recently we've had a bunch of new variants all show up at the same time, so it's really quite a complicated picture going on at the moment," he said.

O'Neale said the rise in October could have been the result of behaviour change after masks and restrictions ended and people socialised more.

Those extra infections could in turn have give some people an immunity boost against the newer variants starting to take off, slowing the rate at which they could spread.

There were 3912 news cases reported yesterday, a similar number to the previous two Tuesdays, and wastewater trends were showing a similar levelling-off.

It was possible one the newer variants - BQ 1.1 or BA 2.75 - would start to dominate, evading immunity and causing a relatively rapid spike out the plateau, but it was too early to say, O'Neale said.

There were also regional differences, with Wellington and the lower North Island leading the way.

"It's a bowl of spaghetti of different trends going on," he said.

Poor data was adding to the difficulty in making a prediction, O'Neale said.

Many of those with Covid-19 were not formally reporting their cases and modellers did not have the full picture of how many people had been previously infected, he said.

Wellington and the lower North Island had seen an increase in cases and an abundance of new variants.

"It is possible that is just better reporting but it is also possible that it is maybe a bit of a forerunner of what we will see as some of those new variants spread into other parts of the country," he said.

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