November 11, 2025

expert reaction to preprint data from the UKHSA looking at level of flu vaccine protection

Scientists comments on preprint data from the UKHSA looking at level of flu vaccine protection.

Prof Adam Finn, Professor of Paediatrics, University of Bristol, said:

“This preprinted study from UKHSA provides important confirmation that the best course of action right now for the British public, old, young and in between, is to get a flu vaccine as soon as possible.  For most school age children and pre-school children from age 2, this is the nasal spray vaccine.  For the rest of us it’s the injected vaccine, usually via your GP but also available in pharmacies either free, or if you are not eligible on the NHS, for sale.

“Getting vaccinated protects you against getting seriously ill with flu, which can occur in healthy people especially the young and the old.  It also reduces the risk of passing flu to others, so protects the vulnerable and helps damp down the epidemic and the pressure on the health service.”

Prof John Tregoning, Professor of vaccine immunology, Imperial College London, said:

“The context of the study:

“The influenza virus season has started earlier than usual in the UK (and other northern hemisphere countries).  This is associated with a change (mutation) in one of the influenza virus strains that is circulating.  The main circulating strain of influenza virus (H3N2) has mutated within the last 6 months.  This is important because the type of H3N2 virus that is infecting people in the UK is slightly different to the H3N2 influenza virus included in the vaccine.  In the study from the UKHSA, they explored the impact of these changes.  Using an animal model (the ferret) that is routinely used for evaluating the immune response to influenza vaccine, they observed that blood from immunised ferrets was less good at recognising the new influenza virus.  However, vaccines work through a range of different ways, not just the way measured in the test.  So the authors also looked at the level of protection observed in people who had been immunised with influenza vaccine this season.  They observed very good levels of protection in children, and good levels of protection in the elderly.  Children who had been vaccinated were much less likely to go to the emergency department or be admitted to hospital than those who had not.  Immunisation in the elderly also reduced the amount of severe disease, but less than in the children.  For context, the level of protection so far this year is similar to last year.  The conclusion is that vaccination is reducing the risk of severe disease following influenza infection at the moment.

“The paper is a pre-print, so it is yet to be peer-reviewed.  This is good quality research and backed up by solid data.  They describe the limitations that this is early in the influenza season, and that there may be changes over time.  The press release reflects the paper well and covers the core elements of the paper.

“There are real world implications of this work – both children and adults should get vaccinated against influenza virus.”

* Preprint title: ‘Early influenza virus characterisation and vaccine effectiveness in England in autumn 2025, a period dominated by influenza A(H3N2) subclade K’ by Freja CM Kirsebom et al.

Posted online by UKHSA: https://www.gov.uk/government/publications/pre-print-early-influenza-virus-characterisation-and-vaccine-effectiveness-in-england-in-autumn-2025

UKHSA press release: https://www.gov.uk/government/news/flu-vaccine-providing-important-protection-despite-new-subclade

Declared interests

Prof Adam Finn: AF provides paid consultancy to several flu vaccine manufacturers including GSK, Sanofi and CSL/Seqirus.

Prof John Tregoning: “Conflicts – I have collaborated with the authors of this study, and also contribute to the NIHR Health Protection Research Unit in Respiratory Infections.  I have received consultancy money from Sanofi and Moderna relating to vaccine research.”