Experts from the World Health Organisation are meeting South African officials for assessing the new B. 1.1.529 coronavirus variant from South Africa. The WHO has labelled the variant as Omicron. According to nomenclature, WHO is giving the most concerning variants the names from the Greek alphabet.

What do we know so far about the variant?

A total of 59 cases of the new variant have been confirmed through laboratory testing. Out of these, three were in Botswana, two in Hong Kong among people who had travelled from South Africa, and the rest were detected in South Africa.

The strain has a large number of mutations and is “clearly very different” from other Covid-19 variants. This was said on Thursday by Tulio de Oliveira, a bioinformatics professor who runs gene-sequencing institutions at two South African universities.

UK scientists came across the new strain on November 23 after samples were uploaded on a coronavirus strain tracking website from South Africa, Hong Kong and then Botswana. Fifty-nine samples of the Omicron variant have been uploaded to the website till date.

“If we look at the results they had up to a week ago, less than 1 per cent of people were testing positive in lots of areas,” a senior scientist said. “That's increased very dramatically in some parts to 6 per cent in the last few days, and so that makes me concerned quite rapidly about people who may be arriving [in the UK] now.”

How is the Omicron variant different?

The virus has already been identified to have 30 different mutations, even though it is being assessed for three days. That is twice as many mutations as the Delta variant, which is the most prominent variant in the UK since past few months.

Richard Lessells from the University of KwaZulu-Natal in South Africa said in a media briefing that the strain's mutations were concerning. “They give us concern this virus might have enhanced transmissibility, enhanced ability to spread from person to person, and might also be able to get around parts of the immune system,” he said.

The mutations can make the variant more transmissible and allow it to evade the protection achieved through prior infection or vaccination.

The UK Alpha variant in late 2020 was 50 per cent more transmissible and increased country's herd immunity threshold from 66 per cent to over 80 per cent. The Delta variant further raised the stakes.

UK scientists have not yet classified Omicron as a “variant of concern”. This is because they do not have enough evidence on the variant's levels of transmissibility. But worries are definitely expressed. “B. 1.1.529 has signatures of cumulative mutation indicating that it emerged in a chronic infection,” said Ravi Gupta, a professor of clinical microbiology at the University of Cambridge. “B. 1.1.529 does certainly look of significant concern based on mutations present.”

“Many have been shown to impact binding by neutralising antibodies and some are known to increase the ability of virus to enter cells or to make them fuse together to allow cell-to-cell spread.”

“Beta was all immune escape and nothing else, Delta had infectivity and modest immune escape, this potentially has both to high degrees,” said Prof Gupta.

There have been many examples of variants that were worrying on paper, but were actually nothing. The Beta variant was highly concerning at the beginning of the year as it was found to be best at escaping the immune system, but later the faster-spreading Delta variant became dominant in the world.

Neil Ferguson, a member of the Scientific Advisory Group for Emergencies, said: “The B. 1.1.529 variant has an unprecedented number of mutations in the spike protein gene, the protein which is the target of most vaccines. There is therefore a concern that this variant may have a greater potential to escape prior immunity than previous variants.”

“However, we do not yet have reliable estimates of the extent to which B. 1.1.529 might be either more transmissible or more resistant to vaccines, so it is too early to be able to provide an evidence-based assessment of the risk it poses.”

It is currently classed as a “variant under monitoring”, that is, it may pose a future risk but currently its impact is unclear. UK scientists are seeking to acquire live virus cultures to be examined, but this takes time. It can take seven to 10 days at least to grow sufficient virus for sharing with other scientists. Officials also have to wait to obtain data from South Africa. The earliest expectation is two to three weeks, but it could also take as long as four to six weeks.

Which countries have banned flights?

Many countries have followed the UK and imposed travel restrictions on flights from southern Africa. Planes from South Africa, Namibia, Lesotho, Botswana, Eswatini and Zimbabwe are not permitted to fly into Britain.

UK travel rules for all six red listed countries

UK Transport Secretary Grant Shapps on Friday said the UK was reviving its red list for travel to “buy more time".

The EU said of planning to stop air travel from southern Africa, as the 27-nation bloc is already recording a spike in cases. The member states are, however, starting to handle things independently.

Germany will only allow Germans flying from South Africa as of Friday night, with even fully vaccinated individuals being required to spend 14 days in hotel quarantine. Italy and France have also placed Mozambique on their red lists, unlike UK. As of Saturday, Czech Republic will ban people who have spent more than 12 hours in the southern African nations.

Singapore and Israel have also imposed flights bans.