A duel Covid and flu jab is currently being tested, vaccination developer Moderna has announced.
Scientists have brought the two separate inoculations together with the trial already under way.
There are further hopes of expanding the jab from a two-in-one to a three-in-one vaccination.
The triple inoculation would cover not only coronavirus and influenza but also lung infection RSV.
This trial is due to be launched within the next two months and if successful it could be available as early as winter 2024.
Dr Paul Burton, Moderna's chief medical officer, was speaking as he called for action over the current vaccination policy.
He said people could find themselves "under-protected and under-vaccinated" if the Government maintained its rules which severely limit who can have the fourth jab.
And he called for younger adults and children to be eligible for booster jabs in the autumn
Dr Burton said that restricting the booster age to 65 will leave "a lot of vulnerable people unprotected".
Vaccination advisers in the UK have said that over 65s, frontline health and social care workers, older care home residents and adults aged 16 to 64 years "in a clinical risk group" should be invited for an autumn booster.
The pharmaceutical firm also announced that its variant vaccine - created specifically to tackle the Omicron variant of the virus which causes Covid-19 - generates a "high" and "strong" antibody response against the sub variants of the Omicron variant - BA.4 and BA.5. "We think this is a strong, powerful antibody response, it is probably long lasting," Dr Burton said.
He said that the firm's variant vaccine could be a "turning point" in the fight against Covid-19. And he said it could "allow us for the first time to get to get ahead of this virus".
He added that the BA.4 and BA.5 subvariants were "more pathogenic" with a higher risk of hospital admission than the original Omicron strain. Dr Burton pointed to data from South Africa where hospital admissions appear to have been higher when BA.4 and BA.5 were the dominant strains compared to the original Omicron variant.
He also pointed to studies which have suggested that the sub variants are better at causing lower lung infections compared to the original Omicron strain - which was more likely to cause sore throats and runny noses. Lower lung infections could lead to a spike in pneumonia cases.
Asked about whether the eligibility criteria for the booster programme should be reassessed, Dr Burton said: "I think what we're going to be looking at come the autumn is a lot of under-vaccinated, under-protected people because maybe they got boosted last November, December, for the holidays, but they're now going to have a long interval where they haven't had a booster.
"So people are going to be under-vaccinated and under-protected and I think restricting the booster age to 65 will leave a lot of other vulnerable people unprotected. Clearly governments will have to make their own public health decisions but my sense is that actually for this upcoming booster season, a broader opportunity to vaccinate everybody, including children, is probably warranted to for consideration."
He said that the firm was due to file for regulatory approval for the variant jab "within days". He added it might even be worth the Government swapping its current stocks of the original Moderna jab with the new variant jab.
"We've talked with public health bodies in the UK, I think there is definite interest in 214 (the variant vaccine). I think the waning of immunity that we see with original vaccines is clear and those bodies understand that the virus is mutating quickly."
On the variant jab's efficacy he said: "Boosting or primary vaccination with (the variant vaccine) really could be a turning point in our fight against the virus because we're able to now see these high antibody levels should provide lasting antibody response." He added: "There is some published data that if you're vaccinated with the (original) vaccine it does reduce transmission, it does reduce shedding.
"It certainly protects against severe disease and hospitalisation. And so I think if we could roll out for late summer, early autumn, boosting, with this vaccine, I think it really would allow us for the first time to get to get ahead of this virus.
"So I think it's important I think it could play a role in preventing transmission, shedding, and I think it would certainly protect populations against infection and certainly severe disease." He said the firm had been creating hundreds of millions of doses of the variant vaccine and is ready to supply large quantities to the UK.
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