What is the 'stealth' Omicron BA.2 variant, is it more transmissible and should we be worried?

The latest Covid study has found a rise in cases of a new Omicron variant with fears it could lead to a surge in cases in the UK.

The Imperial College London’s latest React-1 study found infections in England are rising among those aged 55 and older with experts warning Covid could once again circulate at high levels, driven partly by the new variant.

The sub-lineage of Omicron dubbed "stealth Omicron" was designated a "variant under investigation" (VUI) after a rise in the number of Covid-positive cases showing the sequences by the UK health agency in February.

As of 24 January 2022 - the last available data figures - 1,072 genomically confirmed cases of BA.2 have been identified in England, according to the UK Health Security Agency (UKHSA).

The variant has been reported in 40 countries, with Denmark seeing the biggest rise in BA.2 cases, although experts warn the new strain is on its way to overtaking the BA.1 strain in the UK.

What do we know about this variant of Omicron and could it lead to another rise in Covid hospitalisations and deaths?

Is it more severe than BA.1? And will vaccines be affective against BA.2?

The current vaccines were all designed to work against the original Wuhan variant and with each mutating turn the virus takes, the more vaccine escape there is likely to be.

But that does not mean the vaccines we have are not holding up well - as we saw with Omicron BA.1, while cases soared, serious illness and deaths did not follow to the same degree as before the population was vaccinated. But it is too early to say if the vaccines will give the same level of protection with this variant.

Prof Jonathan Ball, Professor of Molecular Virology, University of Nottingham, said: "Early indicators suggest that the vaccines will provide similar levels of protection as we have seen for Omicron, so this is good news. Whether or not it causes more severe disease will become apparent as more data is collected."

Current evidence shows that does not appear to be causing more severe illness, with vaccines mostly holding out against it, although a dip in immunity among the older population, who had their booster jabs earlier, appears to be behind a rise in hospitalisations.

Prof John Edmunds, Professor in the Centre for the Mathematical Modelling of Infectious Diseases, London School of Hygiene & Tropical Medicine, said: "The good news is that at present there is no evidence to suggest that it is more severe than Omicron and as the UKHSA analysis shows, the vaccines appear to be as effective against it as they are against BA.1.”

Is it more transmissible the original Omicron (BA.1)?

Experts, believe that, yes, BA.2 could be more easily spread.

Asked whether the increasing numbers of BA.2 could lead to a surge in new cases, Professor Paul Elliott, director of Imperial College London’s React programme said the data needs to be tracked carefully.

“It is more transmissible," he said, adding there are been an uptick in infections in the older group that was translating into more hospitalisations.

Prof Edmunds agreed: “BA.2 appears to be even more transmissible than the original Omicron strain (BA.1). 

"It is starting to increase in relative frequency and we might expect it to become dominant in the UK in the next few weeks, as it has done in Denmark recently.  It is difficult to say what the implications of this will be.  It may well extend this wave of infection, or even lead to another peak."

Will we see more Covid variants?

The BA.2 is the latest variant of Covid-19 that is, like all viruses, continuing to adapt to an increasingly immune population.  

But Dr Julian Tang, Honorary Associate Professor/Clinical Virologist, Respiratory Sciences, University of Leicester, said: “Again, as the Omicron variant adapts further to this well-vaccinated human population, we may see more vaccine-escape capable variants arising, with higher viral loads and increased transmissibility, leading to more infections/reinfections as vaccine immunity wanes over time – in a more well-mixed population."

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