One new border-related positive Covid-19 case was reported in New Zealand last night - a 24-year-old who works at the Grand Millennium, in Auckland.

Director-General of Health Dr Ashley Bloomfield is giving details of the case - and also announced 23 new Covid cases in MIQ facilities today.

The new border-related positive case was a man who had a sore throat four days ago. He has not been vaccinated.

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

He travels to work with a colleague, who is being tested. The colleague has 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 are still working to determine the exposure of the security guard's colleagues and community contacts.

Genome sequencing has started but it will 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, a security contractor, 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 vaccination rate of border workers was about 95 per cent, he said.

The Grand Millennium is one of the country's larger MIQ facilities, Bloomfield said. It is the same facility where a cleaner tested positive on March 22.

23 new cases in MIQ - 4 are historical

Of the 23 new cases in MIQ today, 19 are acute, Bloomfield said. He said 17 of the 19 active infections travelled from India.

The Covid-19 pandemic was "very active" around the world, Bloomfield said, which was easy to forget in New Zealand.

New Zealanders did need to keep an eye on what was happening globally. This was the first time we had seen such a high number of cases coming in, he said.

Bloomfield said it has "always been hard" to prevent Covid spreading to the community via the border. He said it wasn't getting more difficult but did require vigilance and hard work.

There was no reason to question the pre-departure tests from people arriving from India, he said.

PCR tests showed they were early-onset infections.

Flights from high-risk countries

That supported the theory people were getting infected during transit in India. Rising rates of infection in India are behind the increasing rates of infection arriving.

The ministry is looking at additional measures that can be put in place in India and New Zealand to prevent transmission during flights, he said.

He said there could be a condition of isolation while awaiting pre-departure test results among other measures.

He would not rule out halting flights from India.

He said they could look at putting all people from high-risk countries in one MIQ facility.

The sequencing led Bloomfield to believe people were being infected in India before the flight and no in-flight transmission had been detected yet.

On vaccine reactions

Bloomfield said people who had allergic reactions to other vaccines had a higher risk of having a reaction to the Covid vaccines. People with food allergies also had a slightly higher risk.

Vaccinators were trained to treat people who had an anaphylactic reaction to the vaccine and the three people who had so far did not require hospitalisation.

There were seven new cases in MIQ yesterday, including one person from the US who arrived on March 22 on a direct flight and tested positive on about day 14 of their stay after contact with a positive case.

The other six cases were all from India, having all flown through the United Arab Emirates.

He will likely also give an update on the vaccination programme which will see 35,000 doses a week being delivered through DHBs and that number only increasing.

"We're in a very different situation from most other countries," he said.

Other countries have had major outbreaks, New Zealand has not.

"We don't want to take our eye off the ball."

He also confirmed yesterday that the Valentine's Day cluster was now officially closed.

That was because it had now been 28 days since the last identified case in the cluster had recovered.

The source of the outbreak has not been determined but all cases were linked through genome sequencing.

Bloomfield said that it was "very likely" that the source of the Valentine's Day outbreak will never be found.

Associate Minister Peeni Henare also fronted yesterday's conference.

Henare, who had his vaccination yesterday, said he had since been feeling well and looking forward to spread the message around the vaccine.

He would promote it in the South Island to Māori communities this week.

The MoH has been in conversations with Māori health providers about the rollout.

Iwi leaders and communications networks have been utilised, and social media will be used too.

He is working with Māori health providers to train more Māori to administer the vaccine.