The potentially more contagious Omicron Covid variant has been found in Britain - and likely Germany and Italy - as many countries, including New Zealand, scramble to restrict travel from southern Africa countries where the new variant originated.
The UK has tightened up rules on mask-wearing and on testing of international arrivals after finding two cases of Omicron.
Amid fears that the recently identified new variant has the potential to be more resistant to the protection offered by vaccines, there are growing concerns around the world that the pandemic and associated lockdown restrictions will persist for far longer than hoped.
Many countries, including New Zealand, have already imposed travel restrictions on flights from southern Africa in the four days since Omicron was first identified in South Africa.
Nine southern African countries are being added to the New Zealand Government's very high-risk countries list - South Africa, Namibia, Zimbabwe, Botswana, Lesotho, Eswatini, Seychelles, Malawi and Mozambique.
It means only Kiwi citizens can travel to New Zealand from those countries and will have to stay a full 14 days in MIQ and undergo testing. The newer MIQ model of 7 days in managed isolation and 3 days at home for other returnees would continue.
Australia, Brazil, Canada, the European Union, Iran, Japan, Thailand and the United States have also restricted travel from the southern Africa continent, in response to warnings over the transmissibility of the new variant — against the advice of the World Health Organization.
Despite the banning of flights, there are mounting concerns that the variant has already been widely seeded around the world. In addition to the UK, cases have been reported in travellers in Belgium, Israel and Hong Kong. Germany also said it suspected a positive case and Dutch authorities were testing whether 61 people who arrived on two flights from South Africa with Covid have the Omicron variant.
The planes arrived in the Netherlands from Johannesburg and Cape Town shortly after the Dutch government imposed a ban on flights from southern African nations. The 539 travellers who tested negative were allowed to return home or continue their journeys to other countries. Under government regulations, those who live in the Netherlands and are allowed to return home must self-isolate for at least five days.
Italian authorities in the southern region of Campania were also investigating whether a person who recently returned home from southern Africa and who has tested positive for the virus was infected with the omicron variant.
In an attempt to slow the spread, British Prime Minister Boris Johnson said it was necessary to take "targeted and precautionary measures" after two people tested positive for the new variant in England.
"Right now this is the responsible course of action to slow down the seeding and the spread of this new variant and to maximiae our defences," he told a news conference.
Among the measures announced, Johnson said anyone arriving in England will be asked to take a mandatory PCR test for Covid on the second day after their arrival and must self isolate until they provide a negative test. And if someone tests positive for the Omicron variant, then he said their close contacts will have to self-isolate for 10 days regardless of their vaccination status — currently close contacts are exempt from quarantine rules if they are fully-vaccinated.
He also said mask-wearing in shops and on public transport would be required and said the independent group of scientists that advises the British government on the rollout of coronavirus vaccines has been asked to accelerate the vaccination program, potentially by expanding the numbers eligible for a booster jab or allowing older children to get a second dose of vaccine.
"From today we're going to boost the booster campaign," he said.
One of the two new cases was found in the southeastern English town of Brentwood, while the other is in the central city of Nottingham. The two cases are linked and involve travel from southern Africa. The two confirmed cases are self-isolating alongside their households while contact tracing and targeted testing takes place.
The British government also added four more countries — Angola, Malawi, Mozambique and Zambia — onto the country's travel red list from Sunday. Six others — Botswana, Eswatini (formerly known as Swaziland), Lesotho, Namibia, South Africa and Zimbabwe — were added Friday. That means anyone permitted to arrive from those destinations will have to quarantine.
The developments come as New Zealand registered its 42 Covid-related death on Saturday - a person in their 80s who passed away in Auckland City Hospital.
There were 145 new community cases announced on Saturday, including 127 in Auckland, 13 in Waikato, four in Bay of Plenty and one in Canterbury.
Of the four in Bay of Plenty, one case was in Kawerau - the area's first taste of Delta.
Regarding Omicron, Covid-19 response minister Chris Hipkins confirmed a public health risk assessment was carried out on Saturday afternoon, which included discussions with officials in Australia, to assess the emerging evidence and any risk to New Zealand from the new variant.
While investigations into Omicron were in early stages, Hipkins was reassured by the fact New Zealand didn't frequently see travellers from those countries.
"Our understanding of the Omicron variant is still very much in its infancy and we're confident this variant hasn't entered New Zealand – several hundred border cases have been identified in managed isolation in recent months and whole-genome sequencing, which is undertaken routinely on all border-related cases, has shown that all have been the Delta variant," he said.
The move comes after the World Health Organisation said preliminary evidence suggested the variant B.1.1.529 variant, which they've named "Omicron", carries a "higher risk of re-infection than other variants of concern".
An advisory group had said it should be designated as "of concern", the organisation said.
Scientists are concerned because the variant appears to have a high number of mutations — about 30 — in the coronavirus' spike protein, which could affect how easily it spreads to people. One UK virologist described the variant as "the most heavily mutated version of the virus we have seen".
Australia made a similar move on Saturday, immediately closing its borders to arrivals from nine African countries and imposing supervised quarantine rules on recent arrivals.
A person in a Northern Territory quarantine facility after arriving from South Africa had tested positive to Covid-19, with genomic sequencing underway to determine whether it was the Omicron variant, Northern Territory Health Minister Natasha Fyles said.
South African scientists identified the new variant this week and said it was behind a recent spike in Covid-19 infections in Gauteng, the country's most populous province.
It was unclear where the new variant actually arose, but it was first detected by scientists in South Africa and had now been seen in travellers to Belgium, Botswana, Hong Kong and Israel.
Professor Michael Baker told the Herald earlier on Saturday the Government should consider putting southern Africa on its "very high risk" travel list.
Travel from "very high risk" listed countries is temporarily restricted to citizens, their partners and children, and parents of children who are citizens.
Other travellers, including New Zealand residents, can enter only if they spend 14 days outside a very high-risk country before their arrival here.
Until today Brazil, Fiji, India, Indonesia, Pakistan and Papua New Guinea were on the list, although all but Papua New Guinea will be removed from December.
However, while the new variant was worrying for people, it was important not to catastrophise the situation, Baker said.
"The best-laid plans can get upset by what the virus does. I hope it won't be the case.
"If this turns out to be a real threat to the effectiveness of vaccines, which is the main worry, then this might mean we have to review our plans for January and February next year on relying on home isolation entirely.
"But look, that's really leaping ahead, it's important not to catastrophise and we need to wait for more information."
New Zealand was among a minority of countries which still managed their borders tightly, with layers of protection like pre-travel testing and quarantine, which put us in a different situation to the rest of the world, the University of Otago epidemiologist said.
"We can keep this virus out if we need to."
There were good reasons to think vaccines would still be effective against Omicron in preventing serious disease and death, University of Auckland senior lecturer Dr David Welch said.
"There are various ways of measuring vaccine effectiveness - the primary measure is whether it prevents serious disease and death", Welch, from the Centre for Computational Evolution and School of Computer Science, said.
"Other measures of vaccine effectiveness are whether it stops people getting infected or whether it stops people transmitting the virus to others when infected.
"There are signs in Omicron's collection of mutations that vaccines may be less effective at preventing infection. Whether onward spread is also more likely at that point remains to be seen."
If vaccines were less effective against the variant at preventing infection and transmission, the unvaccinated would likely be the ones most affected, as case numbers would be higher.
"Everyone will have a higher chance of being exposed to the virus. Getting vaccinated remains the best defence any individual can take against the virus." - Additional reporting AP