Scientists are closely monitoring a sub-variant of Omicron known as BA.2 which has spread widely in many countries around the world.
The rapid spread of BA.2 has led to concerns that it may be more transmissible and it has become known as the stealth variant as it is not as easily identified as a type of Omicron through PCR tests.
The UK Health Security Agency (UKHSA) previously declared it a 'variant under investigation' with experts closely monitoring its growth across countries.
Here is everything we know about BA.2 stealth omicron:
What is it?
It is another strain of Omicron. It was first spotted in November in South Africa. It has 32 of the same mutations as the first Omicron BA.1. but also has a further 28 mutations that are different.
An increasing number of cases are being reported cases across several countries, including the UK. It's has been labelled the 'stealth omicron' as it spread quietly without being picked up for months.
The latest figures suggest there are at least 1,000 cases of BA.2 in England, although this is likely to be a significant underestimate as most test results are not sequenced to determine which variant they are.
Why is it a concern now?
The strain has been found in several countries, including the UK, Germany, India, South Africa and Denmark where the proportion of cases caused by BA.2 is increasing.
BA.2 is becoming increasingly more common suggesting it could soon replace BA.1 as the dominant form of the virus.
Dr Susan Hopkins, chief medical officer for the UKHSA said "We now know that BA.2 has an increased growth rate, which can be seen in all regions in England.
"We have also learnt that BA.2 has a slightly higher secondary attack rate than BA.1 in households."
How severe is BA.2
Experts are still trying to analyse the full extent of the rise of this new variant but have not fully concluded if it is more severe than the previous Omicron.
Dr Tom Peacock, a virologist at Imperial College London said "We do not currently have a strong handle on antigenicity, severity or a much evidence for how much more transmissibility BA.2 might have over BA.1 ."
The scientist did say that very early observations from India and Denmark suggest there is no "dramatic difference" in severity compared to Omicron, but the data is being closely monitored.
More transmissible viruses are still cause for concern as it may lead into greater hospitalisations, deaths and widespread cases even if the strain is considered less severe.
How can I protect myself from it?
As the concerns grow surrounding how transmissible the variant is, caution is being advised in order to prevent a chain of infections that may lead to fatalities.
Dr Susan Hopkins, chief medical adviser for UKHSA said: "Although hospitalisations and deaths remain low, cases are still high in some areas and some age groups so it’s important that we continue to act cautiously as restrictions are lifted.
"Consider wearing a face covering when in crowded places. Take a vaccine to protect yourself against Covid-19. If you have any symptoms, take a test."
Does this mean another vaccine?
It largely depends on how many you have; but no new booster is being suggested at this time. According to the UK Health Security Agency, the existing vaccines are actually better at protecting against BA.2 over BA.1.
Three vaccine doses are 70 per cent effective at preventing symptomatic infections by BA.2 two weeks after the booster and 63 percent effective against BA.1.
Two vaccine doses shows the efficacy after 25 weeks is 13 percent against BA.2 and 9 percent against BA.1
What does this mean as we come out of restrictions?
Data is currently being monitored to evaluate the full extent of these growing cases with little knowledge known about it's severity in comparison to BA.1.
Why has it been called a 'stealth variant?'
It has been called a stealth variant as its initial spread was not widely reported. Yet it has grown exponentially, not just here but also in several other countries.
Suggestions that the variant is harder to detect through lateral flow and PCR tests have been proven to be false, however not all countries have been putting in work to distinguish between BA.2 and older Covid variants meaning its spread has gone undetected.
According to UKHSA, when BA.1 shows up on a PCR test - it can be identified due to a genetic deletion in the virus' spike protein- this elicits whats known as an "S-gene target failure" in some tests which allowed researchers to identify the virus as Omicron.
This genetic deletion is not present in the BA.2 strain, hence why it has gone largely unnoticed and more difficult to classify.
