Doctors in England are being asked to order a different type of flu vaccine in time for next winter.
NHS England says over-65s should be offered a newly licensed jab called Fluad, which experts say should give better immunity to this age group.
It has an added ingredient designed to create a stronger immune response.
This is important for elderly people, because their immune systems are often weaker and respond less well to some vaccines, say experts.
Fluad has been available in Europe for years but was only approved in the UK in August 2017.
Each year, scientists predict which strains of flu are likely to be circulating and advise which strains should go into flu vaccines.
There are also different types of flu vaccine, designed for different groups of patients.
The recommendations for next winter include:
- Children, who are considered "super-spreaders" and are generally more susceptible to flu B, should continue to receive a nasal spray vaccine
- Younger adults in "at-risk" groups, including pregnant women, should get a quadrivalent jab, covering four strains of flu
- People over 65 should be offered the new vaccine, Fluad, which covers three strains of flu
NHS England said there would be additional funding available in 2018-19 for the "highly cost-effective" recommended vaccines.
GPs are reimbursed for any vaccines they buy. Many have already started ordering stock for next season and the Royal College of GPs says some of these orders will be for the wrong jab.
NHS England is asking doctors to get in touch if they encounter any difficulties from manufacturers when placing or amending an order. The deadline for ordering has also been extended to the end of March.
Public Health Minister Steve Brine said: "Our free vaccination programme is world-leading and we constantly review the latest evidence – that's why from next season we are prioritising new and existing vaccines we know offer the best protection."
Prof Helen Stokes-Lampard, chairwoman of the Royal College of GPs, said: "We're pleased that we now have definitive guidance from NHS England, and we hope this will build confidence amongst patients and encourage greater take-up, particularly for those in at-risk groups."