In light of the more transmissible Omicron variant being detected in MIQ, some experts want vaccine booster doses available more quickly.

At present, New Zealanders have to wait at least six months between receiving their second vaccine dose and receiving a booster dose, which tops up immunity.

But with early data suggesting existing vaccines may have reduced protection against Omicron, some health experts are calling for that to be shortened.

Otago University public health professor Michael Baker expects to see Omicron in the community in New Zealand at some point.

"Based on past experience, we do see or did see border failures quite regularly. So yes, we should expect that it would eventually get into the community in New Zealand, unless we took very vigourous efforts to keep it out," says Baker.

Even if all travellers had to return to going through a full 14-day MIQ, as more Omicron cases arrived, the more likely it was to escape, says Baker.

"I think we need to look very hard about how to turn down the tap of infected people arriving here. This will get very clear in the next week or two, as we get more people arriving here and being tested. I would expect Omicron will start to become very common and probably dominant in the next week or two."

That might mean reducing arrivals from countries with high rates of Omicron like the UK, Europe and parts of North America, he says.

So if the new variant does breakout, how protected are people who are double vaccinated?

Dr Fran Priddy, from the research group Vaccine Alliance Aotearoa, says studies so far show two doses don't block infection with Omicron very well at all.

"In lab tests, there's very severely reduced ability to block Omicron ... it's at least tenfold less than the ability to block Delta," Dr Priddy says, with Delta already being more infectious than the original strain.

After all, the vaccines were produced for the first form of the virus that emerged two years ago, and Omicron has significantly mutated since that iteration.

But Priddy says getting infected is not the major problem - more important is how well the vaccines protected against severe illness and death.

At this stage there was not much reliable data about that, she says.

The data that does exist is reassuring - vaccines offer around a 75 per cent ability to prevent hospitalisation.

A study in South Africa showed the Pfizer vaccine was less effective than in the previous Delta wave, however the organisation says the results should be considered preliminary.

But a third shot, a booster, offers even more protection, Priddy says.

"So the third dose of mRNA [vaccine], like the third dose of Pfizer, your antibody level does go back up that should be sufficient to block infection."

Both Priddy and Baker want the government to consider bringing in booster shots sooner than the current six months after a second dose.

The UK, with a huge number of cases, has already changed to three months and in Australia it is now five. The US is still recommending six months or more, but is considering a shorter period.

University of Auckland vaccinologist Dr Helen Petousis-Harris says with what we knew so far, she would like that interval shortened too.

"I'd be going more with five months - not too soon. You do really need to give [the vaccine] time. And also we have to be able to manage is logistically as well."

Director-General of Health Dr Ashley Bloomfield will be talking to government ministers today about advice he has received from the Ministry of Health on the matter.

Figures this week from the ministry show Aotearoa has 2.44 million doses of the Pfizer vaccine in storage, and more will continue to arrive.

About 350,000 people are as of today eligible for a booster and 184,000 have already received it.

-Jordan Bond/RNZ.