It is only a matter of time until there is community transmission of Covid-19's new Omicron variant in South Auckland, says a Pacific public health expert.

There has been a surge in case numbers around the world since the variant was first detected last month, including in South Africa, the United States, the United Kingdom and Australia.

Data from South Africa suggests the numbers of people hospitalised, or dying from the new variant are lower than Delta, but the new strain of the virus is far more contagious.

Auckland University associate professor of public health Collin Tukuitonga says the potential impact of the new strain of the virus in South Auckland is a growing concern.

"There's a lot we don't know about Omicron, but one of the things we do already know is that it is highly transmissible."

He says as a result, areas like South Auckland were likely to be hit hard in an outbreak, because more people were likely to live in overcrowded and multi-generational households where the threat of transmission was greater.

"Omicron is likely to have a significant impact on those communities. I would say it's a no-brainer that that's what's going to happen," Dr Tukuitonga says. "And with this variant it's a matter of when, not if, we get it."

A Counties Manukau District Health Board spokesperson says it's still too early to carry out accurate modelling to say what might happen if, or when, Omicron finally emerged.

They say the data is not yet available to make an educated prediction on possible numbers.

"We expect this to become clearer later in January 2022."

The spokesperson says there are many variables that could influence the impact of Omicron in South Auckland, including the rate of transmission, the severity of infections, the impact on hospital and ICU-level care and how responsive it was to treatment.

University of Auckland epidemiologist Rod Jackson says while we did not yet have any community transmission of Omicron in New Zealand, it appears to be more infectious and therefore the chance of it escaping from managed isolation and quarantine facilities is quite high.

He says if New Zealand got the high case numbers modellers are predicting in other countries like Australia, the threat of it spreading would be that much greater.

"And we know Omicron is a lot more contagious," Prof Jackson says. "So even if the vaccine is preventing 95 percent of deaths, some cases will get through."

He says it's purely a numbers game.

"The good news for us is we were late to the party in terms of the national vaccine roll out and we've vaccinated virtually everyone," Prof Jackson says. "And at the moment that is stopping a lot of cases."

But he agrees with the Counties Manukau DHB that it is too early to make concrete predictions on Omicron.

"At the moment, we just don't know," Prof Jackson says.

He says the fact the new variant was first identified in late November means it is still relatively new.

Prof Jackson says while there are plenty of reports coming out on Omicron in South Africa, there are major demographic differences between countries that needed to be taken into account.

"People are doing their best to make sense of it. But you can't tell until it has worked its way through a complete demographic of a population."