Dubbed ‘Stealth Omicron’, the variant - also known as BA.2 - was first identified in December last year and has been spreading quickly across the country.
Analysis suggests it has a faster growth rate than its parent strain meaning it can spread more quickly, and its structure makes it harder to detect.
It is now on track to become the dominant strain in the UK.
It gained its nickname as it does not have a tell-tale marker on its spike protein, making it more difficult to differentiate from Omicron BA.1 and Delta, but it is still unclear as to whether it causes more severe illness than previous strains.
Dr Meera Chand, COVID-19 Incident Director at the UK Health Security Agency (UKHSA), said: “It is the nature of viruses to evolve and mutate, so it’s to be expected that we will continue to see new variants emerge as the pandemic goes on.
“Our continued genomic surveillance allows us to detect them and assess whether they are significant.
“So far, there is insufficient evidence to determine whether BA.2 causes more severe illness than Omicron BA.1, but data is limited and UKHSA continues to investigate.”
What are the earliest warning signs of Stealth Omicron?
Two key symptoms could indicate infection from Stealth Omicron before testing positive for Covid-19.
Patients may experience feelings of vertigo or dizziness very early on, and this may come and go throughout the day.
The NHS says if this symptom is “constant or very intense”, patients should seek advice from a GP as they may want to investigate further.
Another common symptom which has been found to appear in the early stages if you are infected with coronavirus is fatigue.
Extreme tiredness has been linked to Omicron as well as previous Covid-19 strains and will usually last between five to eight days.
It can leave sufferers feeling ‘wiped out’ despite resting or having a good night’s sleep.
Dr Angelique Coetzee, the South African doctor who first alerted authorities to Omicron back in November 2021 has said that fatigue, alongside muscle aches and pains, can be among the earliest signs of the variant.
The findings come after a new study found that symptoms of Covid-19 can appear as quickly as two days on average after infection.
Until now, health experts, including from the World Health Organisation (WHO), have widely believed it takes between five to six days from when a person is infected with coronavirus for symptoms to show.
What are the other symptoms of Omicron?
Scientists behind the ZOE Covid Study app found that the most common signs of infection from Omicron include:
- a runny nose
- a headache
- a persistent cough
- a sore throat
Several other symptoms have also been linked to the variant which include body aches and pains, particularly in the lower back, night sweats, fatigue, chills, fever, eye soreness, nausea, brain fog, skin rashes and diarrhoea.
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