A leading epidemiologist says the long-term effects of catching Covid-19 could be the most significant consequence of the pandemic.

Daily Covid-19 cases topped 4000 for the first time in three months yesterday, and it remains unclear when this third wave will peak.

Michael Baker. Photo: RNZ / Samuel Rillstone

University of Otago epidemiologist professor Michael Baker told First Up it was hard to tell when this wave of Covid-19 would peak.

"This is very much our third Omicron wave. Fortunately, it's not as intense as the first two but it's certainly happening."

Long term effects of Covid-19 were the biggest worry at the moment, he said.

"They're grouped into Long Covid but there are obviously a whole lot of things that go on and I think the neurological effects can be very severe and quite disabling."

Every time you are reinfected, you run the risk of Long Covid, he said.

"So I think we still want to minimise the amount of times people get this virus."

There were three ways people could protect themselves, Baker said: stay up to date with vaccinations, take precautions at social events and isolate and test if you have symptoms.

People were currently missing out on vaccines that they were entitled to, he said.

"We know that over 50 percent of people who are eligible for their fourth dose haven't had it yet."

The government said it has no plans yet to launch an annual Covid-19 vaccination booster for the majority of people.

But Baker said he was sure it would look at an additional booster in 2023 before winter, when waning immunity became a "real problem".

"The big thing is, whatever booster we have next year will probably be called this bivalent vaccine, so it's going to cover the original strain and Omicron as well."

"It's not so surprising to see those [Covid-19] numbers go up at the moment," Covid-19 modeller Dion O'Neale told Morning Report.

Since restrictions were reduced, a number of new variants which could evade immunity had arrived on NZ shores, O'Neale said.

Currently, about two-thirds of cases would be missed in reporting, he said.

That's because some cases were asymptomatic and would not be testing, he said.

"Around 30 to 40 percent of infections are asymptomatic."

Masking, particularly indoors, and good ventilation were important, he said.

"Everything that worked well for us in the past still works well for us, even with those new variants."