Norwich scientists have warned the rise of a 'stealth' Omicron sub-variant could lead to a second peak in Covid-19 cases this month.
The Quadram Institute, based at Norwich Research Park, has been at the forefront of sequencing samples of the virus since the pandemic began.
Andrew Page, head of informatics at the institute, said a new 'sub-lineage' of Omicron, known as BA.2, is likely to become the dominant cause of Covid-19 cases in the UK this month.
Dr Page said that was "cause for concern", with evidence suggesting the sub-variant is more transmissible than the BA.1 Omicron lineage from South Africa, which triggered the return of restrictions in November.
He said: "Looking around the world, we have seen BA.2 become the dominant lineage, accompanied by mild disease.
"BA.2's ability to outcompete BA.1 is evidence that is more transmissible and tests are now being run to see if this is the case and why."
He said the UK is currently dominated by BA.1 lineage and overall cases have "come down substantially".
But he warned: "We can now see in the sequencing data that the BA.2 lineage is growing rapidly, which is a cause for concern.
"In sequencing data BA.2 accounts for just 1pc of genomes, but this is usually looking back a week or two in the past.
"More up to date, earlier test data from diagnostic testing indicates it now accounts for at least 5pc of cases and is doubling in proportion every four to five days.
"At this rate of doubling, we will see the Covid-19 Omicron BA.2 lineage becoming the dominant lineage in February and this may bring about another peak in cases.
"So, the next month could see more bumps in the road out of the pandemic,, but there are steps we can all take to protect ourselves and each other."
He urged people to get vaccinated, to wear masks in crowded indoor spaces, to keep rooms ventilated and to get tested regularly.
He said: "That is how you can help counter the threat from this stealth Omicron, whilst we keep a close eye on it and any future threats".
Norfolk's Covid case rate, in the seven days up to Wednesday, January 26, was just over 1,223 cases per 100,000 people - a 12pc increase on the previous week.
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