In total, 14 positive Covid-19 cases have been identified in the group: eight are deemed historical; three are new active cases; and further testing of the three new cases reported today may determine if they are also historical cases, according to the ministry.
The ministry said and one previously reported case is now regarded as not a case.
"This case previously tested positive in the United Kingdom prior to travelling to New Zealand and has therefore been determined as a historical case.
"This case is being removed from New Zealand's tally while we confirm it has been reported in the United Kingdom."
The total number of active cases in New Zealand is now 77. Our total number of confirmed cases is 1866.
The total number of tests processed by laboratories to date is 1,441,163.
Meanwhile, the ministry pointed out that all positive Covid-19 tests are sent to ESR for whole genome sequencing as part of ongoing surveillance and our overall elimination strategy.
"Whole genome sequencing has identified a total of 19 cases of Covid-19 at the border with the variant known as B.1.1.7 (UK variant) and one case with the variant identified as B.1.351 (South Africa variant) in New Zealand since 13 December 2020."
It also issued a correction on yesterday's statement.
"Please note that yesterday's media release reported the UK variant as B1.1.17. This was incorrect. The correct variant is B.1.1.7."
"Further work to identify and better understand these variants is ongoing in New Zealand and internationally.
"Current research suggests the B.1.1.7 variant is around one and a half times more transmissible than previous variants but there is no evidence at this stage that the length of the infection period is any different to any other variant of Covid-19, nor is there evidence that it causes more severe illness. We are also closely monitoring emerging research on the B.1.351 variant.
"The recent increase in Covid-19 cases at New Zealand's borders is expected, given case numbers continue to increase globally."
The Ministry also said it was expecting to see more historical cases being detected in managed isolation, due to an increasing number of people becoming infected and recovering before travelling to New Zealand.
While these individuals may still have residual viral particles in their nasopharynx, which are picked up by our tests, they are no longer considered to be infectious.
Anyone who has tested positive must meet the recovered case definition before being allowed to leave the facility as assessed by the medical team. This includes a period of at least 72 hours without any symptoms and a minimum of 10 days since symptom onset or a positive test.
The ministry said that it is continuing to monitor Covid-19 developments overseas, as well as "regularly reviewing" its infection prevention procedure.
"Since 1 January 2021 people arriving from the US and UK are tested on arrival and required to stay in their room until they return a negative test result.
"In addition, pre-departure testing will start to come into effect later this week (11.59 pm NZT on January 15) with the aim of reducing the number of cases of Covid-19 arriving in New Zealand."
The ministry said it would be releasing media updates on Monday, Wednesday, Friday and Sunday.
But any significant development, including any case emerging in the community, would be reported outside the scheduled reporting dates if required.
31 cases yesterday
The Ministry yesterday reported there had been 31 new cases of Covid-19 in managed isolation since Thursday.
"The number of cases reinforces the need for ongoing vigilance at the border, as Covid-19 continues to accelerate overseas," the ministry said yesterday.
Although there are still no community cases of the virus, there were 19 cases at the border which were linked to the new rapidly spreading UK Covid strain.
One case is linked to a separate South African strain.
"Most of these people have come into New Zealand from the UK, via the UAE, Qatar or Singapore," the ministry said.
There is also a strain identified by the Japanese Health Ministry which is being found in people arriving from Brazil that's different from the ones in Britain and South Africa.
The variant was found in airport tests on a man in his 40s, a woman in her 30s and two teenagers. Japan was working with other nations, the World Health Organisation and other medical experts to analyse the new version of the virus, and it is still unclear whether available vaccines will work.
Covid-19 data modelling expert Shaun Hendy warned this morning that a community outbreak of either variant in New Zealand would in all likelihood need a level 4 lockdown to bring it under control.
"If we do have a community outbreak that involves the South African or the UK variants of Covid then we're likely looking at needing to use level 4 to contain and then to eliminate that outbreak," he said.
"Level 3 was effective back in August ... but I think if you take into account the extra infectiousness of these new variants, level 3 is probably not strong enough."
And the Government is being urged to accelerate its rollout of the Covid-19 vaccination, given the increased risk of the new variant.
The National Party wants frontline workers, such as those working in managed isolation and quarantine facilities (MIQ), to get the vaccine as soon as possible.
Party leader Judith Collins wants the Government to consider emergency-use vaccine provisions for essential border workers "before it is too late".
UK strain
The new strain has forced the UK back into lockdown, amid fears its health system will become overwhelmed.
On Saturday, the British government reported the number of confirmed deaths had reached 80,868 - the highest in Europe and the world's fifth-highest pandemic death toll.
A day earlier, the country's daily reported deaths had hit a record high of 1325.
The new and more contagious UK variant can be passed on easier than other strains of the virus.
However, there was no evidence at this stage that the length of the infection period was any different to any other variant of Covid-19 or that it made people sicker, a ministry statement said.
