When did Omicron Covid variant arrive in UK and is it spreading?

Scientists are trying to understand when the variant arrived and if it is spreading in the UK.

The answers to those queries may give clues as to what is to come, even though they seem less important than vaccine effectiveness or disease severity.

If Omicron has been present in the UK for a while, it may suggest that the variant is not likely to out compete Delta and cause a surge of infections or deaths. The picture is not certain if it is a recent arrival or not.

The first case of Omicron was announced by South Africa on November 24th. The first cases were reported in the UK on November 27th in two people with links to southern Africa. There have been 22 cases in England and Scotland.

The first case is not the same as the first one. Prof Oliver Pybus, the co-director of the Oxford Martin school, said that Omicron has been circulating for at least a month.

He said that it was possible that the international spread started at the end of October.

The emergence in October was plausible given that it was the tail end of the Delta wave in South Africa. He said that this is consistent with how and when other variant of concern emerged, such as the Beta variant last year.

The work to estimate the time of Omicron's emergence focuses on comparing patterns of genetic changes that accumulate over time in different samples of the Omicron variant.

There are a number of challenges when it comes to detecting cases of Omicron.

The sheer number of Covid cases in the UK means that only a small percentage of the samples are analysed to identify the variant involved.

In order to boost the hunt, active tracing exercises are under way across the UK, where previously collected samples are analysed to identify the variant they contain.

Omicron has a deletion that means it comes up negative on tests for the coronaviruses S genes. The test can give a quick indication of whether a sample contains Omicron, but it is not conclusive.

The six cases in Scotland that were announced on Monday have been linked to loop back exercises, according to the first minister.

It is unlikely that the Omicron variant has been in the UK for long, according to Dr Jeffrey Barrett, who is leading the Covid-19 genomics initiative at the Sanger Institute.


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He told the Guardian that there was no chance of Omicron in the UK in September or October. It was almost certainly in November that we got the very earliest case.

The date of Omicron's arrival is not the only issue. Is there a degree of community transmission already? If that is the case, experts have warned that tens of cases could turn into hundreds in a few days.

The video explains why Omicron is the most worrying Covid variant yet.

None of the nine Omicron cases detected in Scotland were in people with a recent travel history to countries in southern Africa, or known links with others who have traveled there, according to Scotland's first minister.

Prof Kao of the University of Edinburgh said that it is possible that other people were involved in the event, and that the nine people who account for all the cases in Scotland may have been introduced by other people.

Testing and tracing efforts continue after eight Omicron cases were reported in England on Tuesday.

There is still a long way to go to understand the variant.