Covid-19 Omicron outbreak: Michael Baker suggests a move away from daily case numbers

New Covid infections yesterday dropped from Saturday's record tally but one epidemiologist believes the daily case numbers may not reflect the true extent of community spread.

There were 208 new cases reported in the community on Sunday, down markedly on Saturday's record 247 infections, which was the highest daily total since the pandemic reached New Zealand nearly two years ago.

Yesterday's cases were across Northland, Auckland, Waikato, Lakes, Bay of Plenty, Hawke's Bay, Wellington, Nelson Marlborough and South Canterbury.

One of the new infections in Marlborough was staying at the Tahuna Beach Holiday Park but how the person caught the virus is currently a mystery.

Two hundred and eight Covid-19 cases were reported in the community on Sunday. Photo / Michael Craig

Auckland remains the epicentre of the Omicron outbreak, with more than half of yesterday's new cases in the region.

More than 2000 people are self-isolating at home, including 861 cases.

But epidemiologist Professor Michael Baker believes case numbers under-estimate infection in the community, particularly when numbers are rising rapidly.

"You have got a lot of infected people who haven't developed illness yet and people who have very mild symptoms."

Baker said New Zealand's current average doubling time of 4-5 days is lower than what was previously seen overseas, reflecting how spread was being slowed down due to by the current traffic light settings and contact tracing efforts.

Otago University epidemiologist Professor Michael Baker said New Zealand's current average is lower than what was previously seen overseas. Photo / Supplied

"That approach is still helping to limit transmission, that's why it's so important for people with symptoms to come forward for testing.

"But we know in roughly two weeks' time we will be getting to the stage of moving to the next stage of the response."

Baker said he focuses on the moving average to "smooth out the saw tooth" of daily case numbers.

"It just reminds us yet again not to put too much weight on a single day but instead look at the trend."

Looking at the current moving average, Baker believed cases could reach 300 in the next four or five days. According to his calculations, New Zealand has a moving average of about 160 cases a day.

"In four or five days we could be going up to 300 plus and in two weeks we might be up to 1000 a day.

"None of us likes to predict the future but once you are on the exponential curve it's hard to imagine it changing very much for some time," he said.

As cases were predicted to rise, Baker said those most vulnerable to Covid-19 should start thinking about limiting social interactions.

Even with vaccinations and booster shots, Baker said the elderly and those with underlying health issues can still be vulnerable. But he said the second vulnerable group is the unvaccinated.

"The other groups is of course the unvaccinated, who will be very vulnerable. And the difference now which didn't apply before is there will be very widespread exposure to this virus across the country."

Baker said over half of the country may get infected, meaning most New Zealanders will be in contact with people who have the virus.

Yesterday a dozen people required hospital care across Auckland, Waikato, Rotorua and Christchurch. One person was in an intensive care unit in Rotorua.

While case numbers are soaring, so too are the number of people receiving their booster shots.

There were 48,947 booster doses administered on Saturday, and nearly 5000 paediatric doses were given out.

"With Omicron in New Zealand, one of the best things you can do is get your booster as soon as it is due," the Ministry of Health said yesterday.

Across the country there were 16,873 tests carried out in the last 24 hours - almost 8000 in Auckland.