Airport staff, security guards, hotel receptionists and other frontline border workers will need to start being moved into "low risk" roles from Monday if they refuse to get vaccinated.

Prime Minister Jacinda Ardern today said it was too risky to leave them in jobs where they might contract Covid-19 from those arriving from overseas.

That included people working at managed isolation facilities, airports and ports.

An unvaccinated Auckland security guard was today revealed as the latest Auckland Covid community case, and a further 23 cases - including 19 active - were detected in MIQ overnight.

With most of the MIQ cases arriving from India, Ardern said New Zealand would now temporarily halt people from flying from the country from Sunday until April 28.

The Government was also implementing a further safeguard against Covid escaping from MIQ facilities by ensuring all frontline border workers were vaccinated.

So far more than 80 per cent had been vaccinated, Ardern said.

Border workers unsure about vaccines were initially given time to consider their options and seek more information.

However that time had now run out, Ardern said.

From Monday those workers would need to be vaccinated or moved into roles where they were not in contact with New Zealand's border and overseas arrivals.

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

Few countries, aside from Australia, 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.

Director general of health Dr Ashley Bloomfield today revealed the new Covid community case was an unvaccinated 24-year-old who worked at the Grand Millennium, in Auckland.

The man had a sore throat four days ago.

The person lives alone but Auckland Regional Public Health was investigating contacts with the man's neighbours.

He travelled to work with a colleague, who was being tested. The colleague had been fully vaccinated.

The man worked at Easter, but was not at work or in contact with anyone yesterday. He isolated at home overnight and was being transferred to Jet Park today.

Bloomfield said officials were still working to determine the exposure of the security guard's colleagues and community contacts.

Genome sequencing had started but it would not be completed until tomorrow afternoon.

An assessment of the ventilation in the Grand Millennium was already in progress before the worker was infected.

The border worker would have been offered a vaccination but Bloomfield did not have details on why he had not been. His understanding was the man had not declined a vaccination.

The Grand Millennium was one of the country's larger MIQ facilities, Bloomfield said.

It is the same facility where a cleaner tested positive on March 22.