The strain of Covid-19 detected in Taranaki wastewater is likely the highly-infectious Delta variant, Māori Party co-leader Debbie Ngarewa-Packer says.

Ngarewa-Packer, also a leader with South Taranaki iwi Ngāti Ruanui, said community leaders across Taranaki were told this morning by Taranaki District Health Board during a briefing that it was likely Delta as it was "the only variant around at the moment".

Meanwhile there are three historical cases of Covid to report today in recent returnees in managed isolation facilities.

They include a person who arrived here on July 11 on a flight from the Philippines, via Australia, who tested positive on day 12 of routine testing.

They are in managed isolation and quarantine in Auckland.

The two other historical cases today are a pair travelling together from Uzbekistan.

They arrived on a flight from Uzbekistan, via the United Arab Emirates, last Thursday and tested positive on day 0 of testing. The pair are staying in an MIQ facility in Christchurch.

Five previously reported cases have now recovered. The number of active cases in New Zealand is 54.

The number of active cases in New Zealand is currently 54.

The Ministry of Health is still strongly encouraging anyone in Taranaki with Covid symptoms, or recent arrivals from Australia with or without symptoms who've recently visited Taranaki, to be tested.

All wastewater tests results processed for New Plymouth from Friday, Saturday and some of Sunday are negative.

"A total of 160 swabs were taken in New Plymouth yesterday. Around a quarter of these have been processed and returned negative results, the ministry said.

"There remain a number of results that are pending from swabs taken yesterday that are expected later today.

"A preliminary result, from an early wastewater sample taken for around two thirds of the usual 24 hour sampling time, has come back with no further Covid-19 detected. Results from wastewater samples taken over a wider area in Taranaki are expected tomorrow."

Call for wastewater tests across region

Ngarewa-Packer said she and others were concerned the wastewater testing was currently being limited to the New Plymouth area, and wanted it extended across the whole region due to the "transient" community.

The Maori Party also sought assurances of testing capability regionwide in case of an outbreak, which the DHB was not able to give, she said.

The DHB aimed to test 800 people over the next few days to ensure Covid-19 was not in the community, she said.

Taranaki has some of the lowest vaccination rates in the country, particularly for Māori.

"We are really conscious of the vulnerability of our community and want to make sure everything is being done, and the communications are getting out to the community," she said.

"This shows there need to be proactive local strategies in place, and we have sought a meeting with [Covid-19 Response Minister] Chris Hipkins."

The revelations come as two new positive cases were identified in managed isolation yesterday. There remain no cases in the community.

The two recent arrivals are from the US and the United Kingdom. The US traveller arrived on a direct flight on July 12 and tested positive on day 12 of routing testing.

The traveller from the UK came to New Zealand on a flight via United Arab Emirates and tested positive for Covid on day 0 of their routine tests.

Both people are in managed isolation and quarantine facilities in Auckland.

The Ministry of Health also revealed two new historical cases among the crew of the Playa Zahara fishing vessel struck by Covid-19.

Both mariners continue to be under surveillance testing and are in isolation on board the vessel at the Lyttelton Port, in Christchurch.

Since the start of the year, 105 people have been identified as historical Covid cases out of a total 689 cases.

A total of 19 previously reported cases have since recovered, the Ministry of Health said.

The Playa Zahara fishing vessel arrives at Lyttleton Harbour last week. Photo / The Shipping Database

Part of the update from health authorities also acknowledged the response to the call for people in New Plymouth to get a Covid test, after two positive wastewater results were found in Taranaki last week.

"The ministry continue to strongly encourage anyone in Taranaki with symptoms or recent arrivals from Australia with or without symptoms who've recently visited Taranaki to be tested."

Anyone with flu-like symptoms consistent with Covid-19 is urged to call Healthline on 0800 358 5453.

The number of active cases in New Zealand, as of yesterday, stands at 58. The seven-day rolling average of new cases found at the border is seven.

"One previously reported positive case has now been reviewed and classified as 'not a case' and a second previously reported positive case is now reclassified as under investigation," the MoH statement said.

"Both cases have been removed from our total tally of cases."

The total number of confirmed Covid-19 cases in New Zealand stands at 2506 as of yesterday's official results.