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expert reaction to the Omicron XBB.1.5 COVID variant

Here are some comments from scientists on the XBB.1.5 variant of SARS-CoV-2 in case useful.


Prof Francois Balloux, Professor of Computational Systems Biology and Director, UCL Genetics Institute, UCL, said:

“The SARS-CoV-2 XBB.1.5 strain is defined as an XBB.1 variant additionally carrying the F486P mutation in the Spike protein.  This mutation makes it slightly less immune evasive than its XBB.1 ancestor but more infectious, probably because it increases binding affinity to the human cell receptor ACE2.

“XBB.1.5 is not anticipated to cause more severe disease than other SARS-CoV-2 lineages in circulation.  Immunisation through vaccination and prior infection continues to protect against severe symptoms, hospitalisation and death upon infection with the XBB.1.5 strain.

“The XBB.1.5 strain has rapidly become dominant in parts of the US.  At this stage, it remains fairly uncommon in other countries.  It is still at below 5% in the UK.  It is widely anticipated to go up in frequency globally, and may cause a sizeable fraction of cases globally in the near future.  As such, it could push up case numbers over the coming weeks in the UK.  That said, it remains questionable whether XBB.1.5 will cause a major wave on its own.”


Prof Jonathan Ball, Professor of Molecular Virology, University of Nottingham, said:

“It’s a sub variant of omicron.  There’s no evidence it’s more dangerous.  It might be able to escape antibodies, but that’s not the only immunity we have.  Our immune system is used to adapting to viruses.

“We’d better get used to the emergence of new variants, at least for the foreseeable future.  Yes, they will lead to new waves of infection, but vaccination is still proving to be a very effective weapon to protect the most vulnerable from serious disease.  That’s why it’s incredibly important if you are vulnerable because of older age or because you have other diseases that put you at increased risk of serious COVID to get that immunity topped up and get boosted.  Sars2 is here to stay and we have to get used it, and that means having an adequately funded NHS so we can deal with these inevitable outbreaks.”


Prof Sir Andrew Pollard, Director of the Oxford Vaccine Group, and Ashall Professor of Infection and Immunity, Pandemic Sciences Institute, University of Oxford, said:

“With the recent arrival of the XBB.1.5 COVID19 variant, derived from Omicron, in the US and now UK, we should be cautious not to drive fear that each new variant heralds a new crisis in the pandemic.

“There is no reason to think that XBB.1.5 is of any more concern than other variants that come and go in the ever-changing landscape of COVID19 mutants.

“In the UK today, the issue is not new infections with COVID19, which is just one of many non-pandemic viruses that make us sick, but the chronic shortage of capacity, money and staff in our health and social care system.  These are not easy problems to solve but, unlike pandemics, they are not solved by leaps in science or short-term fixes but by a long-term vision for our health shared across the political divide.”



All our previous output on this subject can be seen at this weblink:



Declared interests

Prof Jonathan Ball: “No conflicts.”

For all other experts, no reply to our request for DOIs was received.

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