It is time to "de-prioritise" the response to Covid-19, which will now be no worse than the flu for the majority of the population, an epidemiologist says.

University of Otago professor Peter McIntyre says the focus should now be on getting those at higher risk double-boosted, rather than worrying about infection control through increased mask wearing or improved ventilation.

That group included the elderly and Māori and Pasifika over 60 years old.

Covid-19 numbers rose in recent weeks, prompting some epidemiologists to talk about a fourth wave of the disease, and calls for the government to enable better ventilation in classrooms and order masking on public transport.

Monday's case numbers released by the Ministry of Health shows the case average for the week has risen on the previous week by 300 cases, up to 2029.

Hospitalisations were also up by 144, with 363 patients in hospital with Covid-19. And the deaths of 21 people were attributed to Covid-19, up from eight the previous week.

Professor McIntyre - also medical advisor for the Immunisation Advisory Centre - says rather than looking at the total numbers we should identify groups that are not double-boosted or don't have antivirals available to them.

"The people we're really worried about now are those people who've got significant underlying diseases or because they're in very advanced years, so we're talking about people over 70 or 75," says McIntyre.

Māori and Pasifika older than 60 years are also in that group, he says.

"For everybody else it's going to be a less severe problem for them than flu."

McIntyre is also head of the Department for Women's and Children's Health at the University of Otago.

He says the combination of the number of historic Covid-19 infections and the country's high vaccination rates means there is a really good level of immunity in New Zealand.

"To be honest I get a bit frustrated ... at the fact this keeps popping up with all these messages about avoiding infection.

"I just think without any disrespect ... to the people who still think that's important, I just believe the game's moved on and we should have our attention elsewhere."

At this point in the pandemic, most rules have finished, though anyone who tests positive must still self-isolate for seven days, and masks must be worn in hospitals in some circumstances. Cabinet voted on 11 April to keep those rules for at least the next two months.

University of Canterbury Covid-19 modeller professor Michael Plank says there has been a significant rise of people admitted to hospital, but it's too early to say whether New Zealand is experiencing a new wave of infections or just a bump.

"I think that's probably a consequence of rising cases in the over 60s who are primarily contributing to those hospital numbers."

Plank says the focus needs to be on getting those at-risk groups double-boosted, but overall the story is an improving one.

"Certainly the direction of travel is in a positive direction around a de-escalation of the risk that we are seeing from Covid-19 and in the long term Covid isn't going to go away.

"So we are going to see a movement towards treating alongside all the other public health issues we have to deal with."

He says attention needs to be paid to hospital admission and death rates rather than weekly infections.

Those indicated that Covid-19 could be attributable for about 1000 deaths a year compared to the 500 attributed to the flu.

Despite this risk, less than 50 percent of those over 50 years of age had taken up the second booster jab.

That's weighing on the mind of West Auckland's Te Whānau o Waipareira clinical governance director Ngaire Harris.

"Covid is more about the hard to reach hearts and minds.

"So you're going to have geographical hard to reach and then there's pockets of whānau like the vulnerable, those that don't have any vehicle, those that don't have any data access."

Harris worries about how low the booster and vaccine uptake is amongst Māori.

Epidemiologist Michael Baker yesterday told RNZ that while the fourth wave of the virus was not as intense as the previous waves, it was definite, with a gradual rise in the number of self-reported cases every day, as seen in RNZ's ongoing database of Covid-19 information.

-Robin Martin/RNZ.