A new sub-variant of the Omicron Covid mutation has been detected in the UK as the country battles a renewed surge in infections.
Coronavirus cases have hit record highs in recent weeks following increased social mixing after the final restrictions were lifted, with infections said to have been fuelled by the highly contagious Omicron BA.2 variant, also known as ‘Stealth Omicron’.
Infections are now continuing to fall across most of the UK, although figures show the virus is still circulating at high levels.
Infections have dropped in England, Scotland and Wales, according to the latest weekly Office for National Statistics (ONS) data. The trend in Northern Ireland is more “uncertain”, although cases remain lower than in recent weeks.
The figures confirm the surge in infections driven by the highly contagious Omicron BA.2 variant is now receding, but prevalence of the virus is still high.
Another Covid variant has also been detected which is a mutation of both the Omicron BA.1 and BA.2 strains, and is referred to as a “recombinant”. Recombinants occur when two Covid strains meet while multiplying and then evolve by sharing their genome or characteristics.
How many cases of Omicron XE are there in the UK?
The Omicron XE variant was first detected in the UK on 19 January.
The UK Health Security Agency (UKHSA) said as of 22 March, a total of 637 cases of the variant had been detected in England.
The variant accounts for only a small proportion of cases, with figures from the ONS showing that 2.9 million people in private households are estimated to have had Covid in the week to 23 April.
Is it more contagious?
The UK Health Security Agency (UKHSCA) is studying the XE variant, which is a mutation of the BA.1 and BA.2 Omicron strains.
The World Health Organisation (WHO) said early tests showed the XE recombinant could be more transmissible than previous strains.
In a report, the WHO said: “Early-day estimates indicate a community growth rate advantage of 10% as compared to BA.2, however this finding requires further confirmation.
“XE belongs to the Omicron variant until significant differences in transmission and disease characteristics, including severity, may be reported.”
The UK Health Security Agency (UKHSCA) said that recent data showed XE had a growth rate 9.8 per cent above BA.2. However, it cautioned that “as this estimate has not remained consistent as new data have been added, it cannot yet be interpreted as an estimate of growth advantage for the recombinant.”
The UKHSCA said: “Numbers were too small for the XE recombinant to be analysed by region.”
XE is not the first recombinant Covid strain to arise in recent months, with the Deltacron variant recently being detected in the UK and the US.
This strain was a combination of Omicron and Delta but it was quickly overwhelmed by the Omicron variant, so it failed to make a substantial impact on case numbers.
What are the symptoms?
As the sub-variant is very new, little is known about the characteristics of the strain, but it is currently not believed to cause any new symptoms.
Much like the Omicron BA.1 and BA.2 variants, most reported symptoms are believed to be similar to the common cold, particularly among those who have been vaccinated.
These include a runny nose, a sore throat and sneezing, as opposed to the original coronavirus strain which primarily caused a fever, a new and persistent cough, and a loss or change to sense of smell or taste.
The NHS recently expanded its official list of Covid symptoms to include nine new signs of infection that have been frequently linked to the Omicron strain. People are now advised to also look out for the following symptoms:
- shortness of breath
- feeling tired or exhausted
- an aching body
- a headache
- a sore throat
- a blocked or runny nose
- loss of appetite
- feeling sick or being sick
Both the WHO and the Centres for Disease Control and Prevention (CDC) in the US have had longer symptom lists for some time, but the UK’s list featured only three symptoms for almost two years.
Professor Tim Spector, lead scientist of the Zoe Covid-19 symptom tracker app, was highly critical of the government’s “refusal” to recognise a “wider array of symptoms”.
He suggested failing to acknowledge the wider list of ailments affecting people with the virus could have driven up transmission rates.
Commenting on the updated symptom list, Prof Spector said: “The addition of more symptoms is definitely a step in the right direction and it could help reduce infections as we go forward.
“However, whilst this is good news, I’d like to see the order of the symptoms changed, as the NHS list puts far too much emphasis on symptoms like fever, and anosmia, which we know are much less common since the Omicron variant emerged.
“According to the Zoe Covid Study, the top five symptoms being reported by contributors with a positive Covid test are runny nose, fatigue, sore throat, headache and sneezing.”