As New Zealanders prepare for their bach getaways and Aucklanders start to leave the region, a new Covid-19 variant is spreading across the world.
Here is everything you need to know about Omicron.
What is the Omicron variant
Omicron is currently present in over 60 countries, having first been reported in mid-November. The B.1.1.529 variant, otherwise known as Omicron, was first reported to the World Health Organisation (WHO) by South Africa on November 24, 2021.
But the new Covid-19 variant was initially detected in four foreign nationals who entered Botswana on November 7, 2021.
Scientists in South Africa raised the alarm due to a sudden surge in Covid-19 cases in the country's Gauteng province, which they suspected were being driven by the new variant they'd identified, The New Yorker reported.
Just a couple of days after, the WHO's Technical Advisory Group named the new variant Omicron and classified it a variant of concern.
How many cases of the Omicron variant are in New Zealand?
On Sunday, five further cases of Omicron were detected in international arrivals, taking New Zealand's total to 13 cases. Of the five cases, four remain in managed isolation, while one has now recovered and been released.
In a statement, the Ministry of Health said the recovered case arrived from London via Singapore on December 7.
"This case tested positive to Covid-19 at day 0/1 and was accordingly closely managed in MIQ. They were never in the community while infectious."
As an extra precaution, 30 other passengers on their flight have been regarded as close contacts. 27 of these passengers have completed day 9 tests and returned negative results.
"Health and MIQ teams have been carefully planning for Omicron cases at the border and will continue to manage all arrivals cautiously. This includes isolation and testing requirements for all new arrivals, robust infection and prevention control and PPE measures at airports and MIQ facilities, and frequent surveillance testing of staff who have any contact with recent international returnees," the Ministry of Health said.
The first detected case of Omicron in New Zealand was announced on Thursday.
The Omicron case flew into New Zealand flew from Germany, via Dubai, on December 10 and is double vaccinated with the Pfizer vaccine.
The person with Omicron is now staying in a special quarantine wing at the Sudima Christchurch Airport MIQ facility.
When did these Omicron cases enter New Zealand
• The first Omicron case arrived in Auckland from Germany via Dubai on December 10 and flew to an MIQ in Christchurch on an aircraft chartered for international arrivals
• Two other passengers on the international flight with New Zealand's first Omicron case have since tested positive
• Another Omicron case travelled from London via Dubai on December 11 and was transported to a Rotorua MIQ on a bus chartered for international arrivals
• A case travelled from Spain via the same Dubai flight and was transported to a Rotorua MIQ
• A third traveller on the Dubai flight tested positive and originally travelled from Nigeria. That person was transported to a Rotorua MIQ
• A case announced on Saturday case travelled on a flight from Singapore to Auckland on 13 December
• Another was on a flight from Singapore to Christchurch on 15 December
• A recovered case announced on Sunday arrived from London via Singapore on 7 December.
The flight details of four Omicron cases are yet to be released by the Ministry of Health.
What does Omicron mean for returning Kiwis?
Passengers on flights with Omicron cases are now required to complete all 10 days at an MIQ facility, rather than spending the final three days in self-isolation. As the variant continues to spread across multiple Australian states, there are new questions about the Government's plan to begin re-opening the New Zealand border in January.
Is Omicron more transmissible than Delta?
Dr David Welch said Omicron is globally the fastest spreading variant we have seen.
Countries like South Africa, Denmark and Australia are seeing large and rapid outbreaks where the doubling time for daily cases is about two to three days.
"All these countries where we are seeing rapid spread have high levels of immunity already, either by vaccination or due to previous widespread outbreaks."
Professor Mike Bunce said evidence to date suggest Omicron might have a more accurate key to our cells.
"This, coupled with its ability to dodge some antibodies, provides clues to why Omicron is causing a new wave of infection even in highly vaccinated countries like Denmark and the UK."
He said recent data suggests Omicron might be better at replicating in our upper airway (bronchus) than previous variants. Meaning it may aid in the spread of the virus from person to person.
What countries are affected by Omicron?
Australia recorded its first cases of Omicron last month - two people who flew into Sydney from southern Africa on November 27 were infected with the strain.
Since then, cases in New South Wales have risen with the state reporting a new record-high number of daily Covid-19 cases on Sunday.
There were 2566 infections confirmed on Sunday, with NSW Health saying it's likely the majority of Sunday's cases are the Omicron variant.
Meanwhile, Victoria reported 1240 new cases on Sunday - the state has a total of 24 Omicron cases. Experts are warning Queensland will soon follow, with the state recording its first Omicron cases earlier this week.
Christmas revellers across Europe are lying low and US officials are intensifying calls for unvaccinated Americans to get inoculated in the face of the new Omicron variant, which threatens to wipe out a second holiday season that many hoped would bail out pandemic-battered industries.
In the United States, President Joe Biden's administration resisted tightening any restrictions, but also sketched out dire scenarios for the unvaccinated in a plea for hesitant Americans to get the shot.
Several European countries are warily watching the spread of Omicron. On Friday, Denmark decided to close theatres, concert halls, amusement parks and museums in response to a rapid rise in virus cases. In Spain, friends and classmates cancelled traditional year-end dinners.
Concerns about Omicron were especially palpable in Britain, which reported record numbers of infections three days in a row this week, the latest on Friday with more than 93,000 cases tallied.
How effective are vaccines against Omicron?
While early studies suggest the Omicron variant may be able to bypass some of the antibody immunity brought about by the Pfizer vaccine, researchers are confident that the jab offers reasonable protection against severe disease.
The Immunisation Advisory Centre's medical director, Professor Nikki Turner, told the Herald this is a vital feature of an effective vaccine.
"This should continue to reassure us of the importance of continuing the heroic efforts of our vaccination programme to ensure as many of our population can access the vaccine as possible."
Moreover, studies suggested a third booster dose of the Pfizer shot may be able to stop Omicron in its tracks.
"A booster dose, or having previously had Covid, appears to be important in restoring much of the reduction in protection to the vaccine," Turner said.
"There is a question as to when the best timing of a booster dose will be, many countries are considering what the best timing for a booster dose would be, and that is a decision that New Zealand is also currently reviewing."
Earlier this week, director-general of health Dr Ashley Bloomfield revealed that he had been given advice in the last couple of days on the time period between getting the second jab and the booster shot.
Currently, there is a six-month period between those two jabs.
He said the advice he has been given in recent days will be up for discussion among Government officials and ministers.
"It may be that a shorter interval will ensure that people do get that booster and increase to their protection at the right time in case we get Omicron in the country."
He expected there would be an announcement on bringing the booster shots forward before Christmas, but that was up to ministers to decide.
-Additional reporting by AP