Covid 19: Omicron incubation period should prompt MIQ stay review - expert

Health authorities should review the number of days returnees spend in MIQ after an Omicron case tested positive days after being released from mandatory isolation, an expert says.

Professor Michael Baker, of the University of Otago, said the recent Palmerston North case, which officials confirmed today was Omicron, was worrying as the person would have thought they were all clear as they went about their daily life in the community.

"It just means we probably need to be back to a more cautious approach for the period as long as we are trying to keep Omicron out of New Zealand."

The person was in a Christchurch MIQ facility and tested negative for Covid-19 five times during their stay before being released on January 16. They tested positive on January 19.

Similarly, UK DJ Dimension, who arrived in New Zealand on December 16, returned three negative tests during his MIQ stay. He returned a positive result from his day nine test after leaving self-isolation and visiting a nightclub and downtown Auckland shops.

Baker said, as the maximum incubation period for the Omicron variant isn't known, it would be appropriate to consider either reverting to the full 14-day stay in MIQ or 10 days in MIQ followed by home isolation and other precautions for four or five days afterward.

"We need to encompass the full range of possible incubation periods," Baker said.

"As we've seen here, it appears that this person's [the Palmerston North case] incubation period was more like approaching two weeks. They got infected before they entered MIQ and had 10 days there and appeared to develop symptoms two days after that.

"An incubation period of this duration would've been detected with the original approach to MIQ but not with a slightly shortened interval. The 10-day period doesn't appear to be sufficient."

The Ministry of Health said today whole genome sequencing had not identified any links to cases in the Christchurch MIQ facility, suggesting the source of infection is offshore, either in the country they travelled from or during travel to New Zealand.

Baker said the latest Covid-19 developments, which included a second Auckland Airport worker testing positive, possibly with Omicron, showed the pattern of the variant was continuing "almost inexorably" towards an outbreak in New Zealand, given the number of infected people turning up at the border.

Recently, another Auckland Airport worker and an Auckland-based MIQ worker both tested positive for Omicron.

Baker said New Zealand had seen "almost every imaginable border failure" happen since the start of the year.

It meant a community outbreak was increasingly likely and New Zealand should reduce travel from high-risk countries and tighten pre-travel testing requirements in a bid to delay entry of Omicron for a period to allow better preparations for its arrival.