There 6636 are new community cases of Covid-19 today and a further seven Covid-related deaths have been reported.

A second person who has travelled from overseas to New Zealand has been confirmed as having the BA.4 variant of Omicron.

There are 480 cases in hospital, including 12 receiving intensive care treatment.

Both of the two identified border cases with the BA.4 variant are currently isolating at their homes.

The variant has been reported in southern Africa and Europe, and in New South Wales, the ministry said in a statement.

"The arrival of this sub-variant in New Zealand is not unexpected.

"At this stage, the public health settings already in place to manage other Omicron variants are assessed to be appropriate for managing BA.4 and no changes are required."

The seven deaths reported today include people who had died over the previous two days.

One person was in their 40s, one in their 50s, three in their 80s and two people were aged over 90.

Three people whose deaths were reported today were from Auckland, one from Waikato, one from Bay of Plenty, one from Wairarapa and one from Canterbury.

The locations of today's cases are Northland (141), Auckland (1956), Waikato (423), Bay of Plenty (215), Lakes (105), Hawke's Bay (167), MidCentral (266), Whanganui (68), Taranaki (206), Tairāwhiti (77), Wairarapa (71), Capital and Coast (419), Hutt Valley (179), Nelson Marlborough (275), Canterbury (1120), South Canterbury (98), Southern (784) and the West Coast (63).

The location of three cases was unknown at the time of the Ministry's 1pm statement.

Meanwhile, 90 Covid-19 cases have been detected at the border.

In the community, there are 52,860 active cases of the virus.

An active case is a case identified in the past seven days and not yet classified as recovered.

Today's seven-day rolling average of case numbers is 7553 while last Monday it was 8355.

There are 480 people with Covid-19 in hospital. They are in: Northland (27), Waitematā (78), Counties Manukau (64), Auckland (90), Waikato (35), Bay of Plenty (26), Lakes (one), Tairāwhiti (three), Hawke's Bay (11), Taranaki (four), Whanganui (two), MidCentral (nine), Wairarapa (two), Hutt Valley (six), Capital and Coast (11), Nelson Marlborough (eight), Canterbury (74), South Canterbury (four), West Coast: (one) and the Southern region (24).

The average age of cases hospitalised in the Northern region is 59.

The vaccination statuses of cases in Northern region hospitals (excluding emergency departments) is:

• Unvaccinated or not eligible: 41 cases / 16 per cent
• Partially immunised <7 days from second dose or have only received one dose: Seven cases / 3 per cent
• Double vaccinated at least seven days before being reported as a case: 73 cases / 29 per cent
• Received booster at least seven days before being reported as a case: 125 cases / 50 per cent
• Unknown: Five cases / 2 per cent

On testing, 1.6 million RATs were dispatched in the seven days to May 2.

In the last 24 hours, 2426 PCR tests were processed.

On Covid-19 vaccinations, 95.2 per cent of eligible people aged 12 and older have been double dosed and 70.9 per cent have been boosted.

Modellers are saying New Zealand's next Covid-19 wave could take off at the back end of winter.

While daily case numbers in the Omicron outbreak continue to drop, modellers are saying New Zealand's next Covid-19 wave could take off at the back end of winter.

There were 5656 new cases in the community and six people died with the virus in yesterday's ministry update.

There were 466 people with Covid in hospital, including 16 in ICU or HDU.

The seven-day rolling average of case numbers was 7414, which is down by more than 1000 compared to last Sunday's 8435.

The ministry reported yesterday that a traveller from South Africa was found to have the BA.4 variant of Omicron - the first time it had been detected here.

"BA.4 has been reported in Southern Africa and Europe, and a case was reported in New South Wales a few days ago. The arrival of this sub-variant in New Zealand is not unexpected."

Current public health measures in place to manage Omicron were appropriate for managing BA.4.

Experts say the new Omicron variant detected may increase the risk of Covid-19 reinfections.

Professor Michael Baker, from the University of Otago, said this was because new variants were slightly better at evading New Zealand's existing immunity, which was of concern.

"People who have been vaccinated or have had prior infection or both suddenly start getting the infection again. That is going to be more likely if they are new variants because they will be a bit more different from the viruses we had before," said Baker.

Dr David Welch, from the University of Auckland, said the new sub-variant was serious but unlikely to be significantly different from the dominant sub-variant in New Zealand, BA.2.

"In terms of severity, we would expect to see similar levels to what we saw with BA.1 and BA.2 - less severe than Delta and on a par with the original Wuhan strain," he said.

The number of reinfections would also be an important indicator of a new wave of Covid.

"If we start to see a significant increase in these, then that would point to the possibility of a second wave being driven by waning immunity," said Covid-19 modeller Professor Michael Plank.

Meanwhile, after more than two long years, international tourists are once again allowed into New Zealand.

From this morning, visitors from around 60 visa-waiver countries can now travel here without isolation if they are vaccinated and do a pre-departure and arrival test for Covid-19.

Tourism Minister Stuart Nash said thousands of passengers were expected to arrive on about 25 flights at Auckland, Wellington and Christchurch international airports in the next stage of the reopening plan.

This comes as Lamp (loop-mediated isothermal amplification) tests will be trialled at Auckland Airport. The test is said to be more accurate and returns results in 30 minutes.

They will be trialled at the airport, initially limited to 30 Air NZ staff, and could eventually be used in hospitals, aged care and other sectors, Associate Minister for Covid-19 Response Dr Ayesha Verrall said this morning.

"The Lucira test is shown in clinical trials to be ... close to the accuracy of PCR tests, but also the convenience of being a test you can purchase and then take with you to wherever you need it," she said at a press conference at Auckland Airport.