Teachers are most vulnerable to Long Covid, which can still affect people four years after catching the virus, a new study shows.

University of Otago associate professor Amanda Kvalsvig led the research, which looked at an evidence summary around Long Covid.

She told Morning Report Covid-19 needed to be taken seriously.

"A number of scientists here and internationally are now quite convinced that the prevalence [of Long Covid] is likely to increase, and that's a reason to take preventive action.

"There's been a lot of optimism that it will just go away, and we're now seeing very firm evidence that that is not going to happen."

Global studies estimate between four and 14 per cent of people infected with Covid-19 get ongoing, long-term symptoms ranging from mild to severe.

Amanda says some of the co-authors on the report had experienced Long Covid.

"Some people who had Long Covid early in 2020 are still not well.

"So the experience of being not listened to and not believed has been very harmful for them alongside the very considerable health impacts that they've had from Long Covid."

The report found there was no cure for Long Covid, so its management was limited.

Amanda says a government response was crucial.

"The cost of inaction is going to be very high and that's going to be a human cost and a financial cost.

"We're seeing that very clearly."

Teachers in New Zealand were most vulnerable to getting Covid-19, followed by healthcare workers, she says, so they were in turn most vulnerable to getting Long Covid.

The report recommended three actions for the government to take immediately.

They included risk assessment, reducing the spread of Covid, and extending vaccine eligibility to younger groups.

It says Covid-19 was a "syndemic condition" causing chronic disease, which in turn led to increased susceptibility to Covid-19.

"There are profound health-equity implications for Māori and Pacific Peoples and people with disabilities or underlying chronic conditions," the report found.

University of Otago epidemiologist Michael Baker is one of the 14 authors of the study.

He told First Up that so far, it showed Long Covid could persist for four years - the length of time data had been available.

"It's disabling for a lot of people and our overall conclusion is that we need to act very vigorously to manage this risk," Michael says.

There were more than 200 individual symptoms linked to Covid-19, he says.

"It does have a very broad range of effects, but dominant effects would be fatigue and brain fog."

While some were short term, mild and transient, other effects could be life-altering like heart attacks, strokes, diabetes, chronic fatigue syndrome and a whole range of neurological effects.

Michael says the government needed to step in.

Evidence showed Covid could be damaging to the entire New Zealand population, including foetuses, he says.

"We think it's going to affect things like productivity in our workforce and demand for healthcare services.

"So, prevention is much better than having to respond to an increasing number of people with long-term disability from this infection," Michael says.

However, the government would not commit to adopting minimum standards to prevent it, National Party deputy leader Nicola Willis says.

She told First Up there were no plans to introduce guidelines on ventilation and air quality.

The Ministry of Health had set up a programme to support patients with Long Covid, and also an advisory group to assess evidence and advise on practice guidelines, she says.

"I would just say to anyone who's got Long Covid, we recognise that that can be really difficult and it sits alongside a number of those chronic health conditions we seek to manage through our public health system."

- RNZ