Covid-19: Potentially dozens of undetected Omicron cases, modeller says

Stuff
Prime Minister Jacinda Ardern has announced a nationwide move to the red Covid traffic light setting from midnight on Sunday.

“Dozens” of undetected Omicron cases may already be in the community, a Covid-19 modeller says, after confirmation of an outbreak prompted a move into the “red light” response phase.

Nine positive cases have been detected – a family in Motueka in the top of the South Island, as well as a flight attendant.

An infected family flew to a large wedding in Auckland in mid-January. The Sky Tower, some airports, Air New Zealand flights, supermarkets, and a KFC are among the locations of interest listed by the Ministry of Health.

Prime Minister Jacinda Ardern broke the news on Sunday, moving the country to the red light setting. Its main function limits large gatherings to 100 people.

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* Covid-19 NZ: New Zealand to move to red at 11.59pm tonight after mystery Omicron cases
* Covid-19: Vigilance urged as community Omicron case confirmed in Auckland

University of Canterbury Covid-19 mathematical modeller Professor Michael Plank, says there is a high likelihood of “significant” case numbers.
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University of Canterbury Covid-19 mathematical modeller Professor Michael Plank, says there is a high likelihood of “significant” case numbers.

“Omicron is now circulating in Auckland, and possibly the Nelson/Marlborough region, if not elsewhere,” she told media at a hastily arranged press conference in Wellington.

Covid-19 modeller Professor Michael Plank said it was very likely there was “significant” undetected transmission – given there was no established link to the border yet, and that large social events were involved.

“There’s likely to be a chain of transmission that’s led to these cases, which we haven’t found yet.

“I can’t put an exact number on it, but it could certainly be dozens.”

He said it was most likely cases could crop up in Auckland or Nelson/Tasman, but five Air New Zealand flights (between Auckland and Nelson, and New Plymouth and Auckland) could affect people from “all corners of the country”.

It was likely some people already had symptoms, while others were in the incubation period.

Immunologist James Ussher​ said the Nelson cases could be the “canary in the mine”, just the first transmission detected.

“There must be a high chance that other people from the wedding might be infected,” he said.

Thousands turned out in Mount Maunganui to watch rugby and cricket stars face off in the T20 Black Clash. Pictured: BJ Watling, of Team Cricket.
Hannah Peters/Getty Images
Thousands turned out in Mount Maunganui to watch rugby and cricket stars face off in the T20 Black Clash. Pictured: BJ Watling, of Team Cricket.

Getting a booster dose of the vaccine reduced the likelihood of infection by about 50 per cent, and provided excellent protection against severe illness – reducing that by about 90 per cent, Ussher said.

Meanwhile, popular music and sporting events have drawn large crowds around the country this weekend, including an LAB concert in Auckland on Saturday, the Auckland Marathon on Sunday, and the Black Clash in Mount Maunganui.

Microbiologist Dr Siouxsie Wiles​ said if anyone was infectious at those events, symptoms would likely show up for most people in the next few days.

They could be as light as a headache, sore throat, or sniffle.

Microbiologist Siouxsie Wiles says she is concerned red light settings aren’t enough with high risk environments still open.
RICKY WILSON/Stuff
Microbiologist Siouxsie Wiles says she is concerned red light settings aren’t enough with high risk environments still open.

She was concerned the red light setting – which allows hospitality businesses to cater for up to 100 – wasn’t enough to limit transmission.

“It doesn't matter if groups of people are seated one metre away from each other, if you are in a confined space, with bad ventilation and everyone’s got their masks off, then transmission happens.”

Wiles said lockdowns had been proven to work, and gave more time to get vaccination rates up, but they impacted social cohesion – and were not easy to implement for all communities.

Plank said there was a “small chance” the current outbreak could be contained to relatively low numbers, but the country had to prepare for high case numbers, potentially rising from thousands to 10,000 per day.

“That will sound daunting for people, but we do have to emphasise the individual risk of getting severe illness, for many people, will be low.”

While Omicron was much more infectious it could be slowed down – by getting a booster, masking, and social distancing.