Scientists say they are keeping a close eye on a mutant covid strain as the number of cases rose to more than 600. Latest figures from the UK Health Security Agency show there have been 637 identified cases of XE - a blend of two omicron strains.
The earliest of these was on January 19 this year however they say there is insufficient evidence to draw conclusions about how the variant will grow. It means they will continue to keep watch on it to see how it develops.
The scientists have been looking at three recombinant variants which have been identified in the UK. A recombinant variant happens when someone becomes infected with two or more variants at the same time which means the variant's genetic material mixes in the patient's body.
This is not unusual and has happened several times during the pandemic. Most do not give the virus any advantage and die out quickly.
UKHSA’s new analysis has looked at the recombinants known as XF, XE, and XD. Of these, XD and XF are recombinants of Delta and Omicron BA.1, while XE is a recombinant of Omicron BA.1 and BA.2.
In the UK, 38 cases of XF have been identified, though none have been seen since mid February. There is currently no evidence of community transmission within the UK.
XD has not been identified in the UK to date. A total of 49 cases have been reported to global databases, the majority of these are in France.
There have been 637 cases of XE – a recombinant of Omicron BA.1 and BA.2 – confirmed in the UK so far. The UKHSA said there is currently insufficient evidence to draw conclusions about growth advantage or other properties of this variant adding: "We continue to monitor all recombinants closely, routinely through our world-leading genomic surveillance and sequencing capability."
Professor Susan Hopkins, Chief Medical Advisor, UKHSA said: "Recombinant variants are not an unusual occurrence, particularly when there are several variants in circulation, and several have been identified over the course of the pandemic to date. As with other kinds of variant, most will die off relatively quickly.
"This particular recombinant, XE, has shown a variable growth rate and we cannot yet confirm whether it has a true growth advantage. So far there is not enough evidence to draw conclusions about transmissibility, severity or vaccine effectiveness. UKHSA will continue to monitor the situation closely as a matter of routine, as we do all data relating to SARS-CoV-2 variants both in the UK and internationally."
Figures for the latest number of case rates, issued on Monday, show there were 604,919 infections recorded in the past seven days. This is a rate of 901.8 per 100,000 people.
The UKHSA's variant technical briefing also includes updated analysis on Omicron BA.2, currently the dominant variant in the UK.
BA.2 is estimated to account for approximately 93.7 per cent of cases in England, with the highest prevalence in the South East (96.4 per cent) and the lowest in the East Midlands (91.1 per cent). Data for Scotland, Wales and Northern Ireland is not included in the UKHSA Technical Briefing.
BA.2 continues to demonstrate a substantial growth advantage. Since the middle of February, this growth rate has settled at approximately 75 per cent higher than other circulating Omicron lineages in England.
Ongoing analysis by UKHSA has found no evidence that infection with Omicron BA.2 results in a greater risk of hospitalisation, compared to Omicron BA.1.
UKHSA last week published further vaccine effectiveness data against hospitalisation following a booster dose. For the first time, this data includes analysis on vaccine effectiveness 15+ weeks after the booster dose.
This data shows that protection against severe illness from COVID-19 remains at over 90 per cent in those aged 65 and over up to 14 weeks after a booster dose. While there is a suggestion that this wanes slightly after 15 weeks, protection in this age group remains high at over 85 per cent.
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