New Zealand has suspended travel from India in response to a surge in Covid cases among travellers to this country.

The ban will begin on Sunday and will remain in place until April 28.

The travel halt follows news that 17 of the 23 new Covid cases in managed isolation announced today had arrived from India.

While arrivals from India had triggered the risk assessment, Prime Minister Jacinda Ardern said the Government would be looking at risks posed by other Covid hotspot countries.

"This is not a permanent arrangement but rather a temporary measure," Ardern said.

The temporary hold would also help reduce the risk that travellers themselves faced, she said.

Health teams would use the time until April 28 to try and plan safer ways to accept travellers from India.

But there were no guarantees officials would come up with a better solution.

"We haven't identified anything obvious ... but we have to try and do better," Ardern said.

She wanted to look at the quality of PCR Covid testing in other countries and whether tests were being taken in the 72 hours before departure.

Health teams may also look at the flight routes arrivals took, not just their country of origin.

Auckland Indian Association president Narendrabhai Bhana said he had no problem with the Government's decision to temporarily suspend flights from India.

"We do realise that there are a large number of Covid cases in India at the moment," he said. "It's for the safety of our Kiwi citizens.

"We really have no problem with the New Zealand Government suspending flights from India until we can get on top of it."

Ardern said more than 80 per cent of border workers had now been vaccinated.

Those who are not vaccinated were set to be moved into other roles and would not be able to remain in a Covid high-risk job, Ardern said.

Her expectation was that all the country's frontline border workers had to be vaccinated.

The Government allowed time for those who didn't wish to be vaccinated to consider their options and seek more information.

However, from Monday those who still did not wish to be vaccinated would now need to move to other roles.

There were few other countries, aside from Australia, that had been operating managed isolation facilities in a similar way to New Zealand.

That was why it had been "an enormous" challenge to keep all arrivals and all workers in those facilities safe and healthy, she said.

More than 60 cases in MIQ in a fortnight

New Zealand had space in its quarantine facilities and today's announcement was about reducing risk.

It was very clear from the fact that New Zealand has had more than 60 cases in MIQ in the last two weeks that the Government had to review its options to reduce the risk, she said.

When asked why it has taken so long to implement a plan like this, given epidemiologists had been talking about it earlier, Ardern said her team had been considering their options for some time.

New Zealand could not prevent citizens from arriving in the country permanently, that was why this was a temporary halt on arrivals lasting until April 28.

Ardern said testing had shown that some of the arrivals had contracted Covid just before departing from their country of origin and that was why the temporary halt was needed.

She said people were getting sick in the act of coming to New Zealand, not necessarily on the plane, but even just heading to the airport, she said.

Ardern said she couldn't answer whether the halt on arrivals from India would last longer than April 28.

She said she wasn't looking at suspensions of arrivals from other countries at the moment.

While there were other high-risk countries, they didn't have as many people travelling to New Zealand, she said.

Covid cases were spiking again, particularly in India and Brazil, and New Zealand was not immune, Ardern said.

The Government had been reviewing its border settings in recent weeks, Ardern said.

She said ultimately New Zealand wanted to see fewer cases arriving in the country.

Director general of health Dr Ashley Bloomfield today revealed 19 people in managed isolation facilities had been diagnosed with active Covid-19 cases overnight, including 16 who had travelled from India.

The other three positive cases arrived from Pakistan, Egypt and England.

All travelled through the United Arab Emirates en route to New Zealand.

The influx of cases followed news of a new Auckland community case after a worker at the Grand Millennium managed isolation and quarantine facility also tested positive.

Experts, such as University of Otago public health researcher Nick Wilson, had earlier been calling for tougher entry conditions on those arriving from so-called red zone countries where Covid was spreading freely.

And Bloomfield said today's high number of MIQ Covid cases was significant.

The ministry was now looking at additional measures to help stop Covid transmission during flights between India and New Zealand, and travellers might also have to isolate in India while awaiting pre-departure tests, he said.

Bloomfield didn't rule out halting flights from India and said health teams could also look at putting travellers from high-risk countries into one MIQ facility.

The Ministry of Health had reported 146 new Covid cases at the border between March 1 and April 7.

Only four of those cases flew on direct flights from the US, and five American returnees arrived via Asia, the Spinoff reported.

Of the remainder, 94 came from India and 14 from Europe.

Nearly all the cases from India and Europe arrived in New Zealand on flights that transited in the UAE, Singapore or Qatar.

Despite that, only two international air routes - from San Francisco and Los Angeles - were deemed high risk.

Wilson told the Spinoff that designating only those two routes as high risk didn't make sense.

"There is an increased risk from not having stricter rules applied to all air routes from red zone countries. They should all be raised to the San Francisco and LA standard and then higher still," he said.