Stealth Omicron Covid variant: symptoms of new BA.2 coronavirus strain, what is it - and should we be worried?

Omicron BA.2 was named a ‘variant under investigation’ on 21 January and more than 400 cases have been detected in the UK

A new Covid-19 strain known as ‘stealth Omicron’ is now under investigation in the UK.

The UK Health Security Agency (UKHSA) has confirmed more than 400 cases of Omicron BA.2 have been reported in England so far, and early analysis suggests it has a faster growth rate than its parent strain.

Omicron symptoms tend to be very similar to the common cold (Composite: Mark Hall / JPIMedia)

What is known about ‘Stealth Omicron’?

The first case of the Covid-19 sub-variant in the UK was detected on 6 December 21, but it was initially found in the Philippines, although it is not known where it originated. Denmark has also reported high numbers of the variant.

It was named a ‘variant under investigation’ on 21 January and it acquired its name 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.

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In the UK, some 426 cases of the BA.2 sub-lineage have been sequenced, according to Reuters, and the UKHSA said early analysis suggested an increased growth rate compared to BA.1.

Research shows that Stealth Omicron now accounts for every one in 100 coronavirus cases in England, but there is currently not enough evidence to indicate whether it causes more severe illness than previous strains.

Dr Meera Chand, COVID-19 Incident Director at the 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 symptoms of Omicron?

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Symptoms of Omicron have proven to be more wide ranging than the original Covid-19 strain, which can make it difficult to spot.

The NHS still recognises three symptoms as the main signs of coronavirus infection and urges people to self-isolate and take a test if they experience any of the following:

  • a high temperature
  • a new, continuous cough
  • a loss of change to your sense of smell or taste

However, the most common signs of Omicron typically differ from the ‘classic three’.

Scientists behind the ZOE Covid Study app found that most people who test positive for Omicron are reporting symptoms that are closer in nature to the common cold.

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According to the app, the main signs of infection from Omicron are:

  • a runny nose
  • a headache
  • Sneezing
  • a persistent cough
  • a sore throat

Other symptoms that have also been linked to the variant include body aches and pains, particularly lower back pain, night sweats, fatigue, nausea, skin rashes and diarrhoea.

Scientists identified the main symptoms from people reporting positive cases on the app in December 2021, when Omicron became dominant in the UK, and compared this with data from early October when Delta was the dominant strain.

Tim Spector, Professor of Genetic Epidemiology at King’s College London, and leader of the ZOE Covid study, has warned that people need to be aware of emerging Omicron symptoms as infection can easily be mistaken for a cold.

Prof Spector said: “A lot of the Omicron symptoms, the majority of them are looking like the common cold or some other viral illness, without any of the classic symptoms.

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“So do be aware of the main ones. Unfortunately the government hasn’t yet taken this on board and are one of the only government’s in the world not to tell its citizens what the symptoms are.

“But they are runny nose, headache, sneezing, persistent cough and sore throat.

“They are the top five at the moment, so do keep any eye out for them and try not to infect anyone else.”

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