Scientists are warning that the NHS has no treatments proven to work against severe flu.

A leading expert who discovered the first drug to work against Covid-19 is expanding that trial to find out which could save lives once people are hospitalised with the flu. Prof Sir Peter Horby made the warning at a media briefings about the current surge in infections driven by the new H3N2 strain which is thought to be more dangerous for older people.

It comes as the boss of NHS England said flu cases may be "starting to settle in some parts of the country" after hospitalising record numbers for the time of year.

• Super flu VERDICT from Britain’s top scientists - everything you need to know

• Doctors out in force on picket lines outside NHS hospitals at start of 5-day strike

Sir Peter Horby, professor of emerging infections and global health at Oxford University, said: "We've got 2,500 people in hospital as of today, at least, and we don't have any treatments that are proven to be effective in patients with severe influenza.

"We've got more treatments for Covid, which is five years old, than we do for flu, which is 90 years old. There's no reason for that other than lack of investment and lack of adequate trials."

Professor Horby was knighted after the role he played in the pandemic when he was the co-chief investigator for the largest clinical trial of Covid-19 in the world. His RECOVERY trial announced in June 2020 the first results identifying a drug which worked against the new virus.

Sir Peter gave a statement in a Downing Street briefing alongside then-PM Boris Johnson stating that giving Dexamethasone to hospitalised patients would save lives - and it immediately became the standard treatment around the world. It was announced in 2023 the RECOVERY trial would be expanded to include treatments for flu and now it is investigating the effectiveness of three existing drugs. They are two antivirals Tamiflu and Xofluza as well as a form of steroids.

The media briefing in central London heard on Wednesday that there was good evidence that drugs like Tamiflu could reduce the duration of flu if given to someone within 48 hours of mild symptoms starting, but there is no robust evidence for what medics should give for those severely ill after the illness has progressed.

The new H3N2 strain - dubbed ‘superflu’ - is driving an early flu surge and experts are unsure whether it will peak early and then drop off - or remain at high levels for months.

Some hospitals across the country have asked staff, patients and visitors to wear face masks to cut the spread, while others have gone in and out of critical incident status due to the high number of people attending A&E.

NHS England data last week showed an average of 2,660 flu patients were in hospital each day, up from 1,717 the previous week. At the same point last year the number stood at 1,861 patients, while in 2023 it was just 402.

Weekly flu numbers in England peaked at 5,408 patients last winter and reached 5,441 over the winter of 2022/23, the highest level since the pandemic. Professor Antonia Ho, Honorary Consultant in Infectious Diseases at Glasgow University, said vaccines were just effective this year as in previous years but unveiled data showing how they are less effective in the elderly.

European surveillance data showed current vaccines were 32% effective at preventing hospitalisation in over-65s who catch the new strain, compared to 66% in 18 to 64-year-olds and 73% in under-18s.

Prof Ho said: “H3N2 particularly impacts on the elderly. So we tend to see more hospital admissions and they tend to stay in hospital for longer as well.”

The infectious disease experts insisted these levels of protection were similar to previous years and that vaccination was still the best protection against the flu surge. They now suspect the early flu surge may be due to the new strain and waning immunity against it since the Covid-19 pandemic.

At a separate hearing of the Health and Social Care Committee in Parliament, the NHS England chief executive offered some hope. Sir Jim Mackey told MPs: "We've actually had our first contact with winter in a pretty nasty way over the last month.

"Two weeks ago, I really worried about... the way flu was accelerating the pressure in certain systems. That looks like it might be starting to settle, still early days, but might be starting to settle in some parts of the country.”

Latest weekly flu hospitalisation data from NHS England will be published on Thursday.