It is safe for people to get coronavirus and flu vaccines at the same time, new research suggests.
A clinical trial found that reported side effects were mainly mild to moderate.
There were also no negative impacts on the immune response produced by either vaccine when both were given on the same day, in opposite arms.
The Combining Influenza and Covid-19 Vaccination (ComFluCov) study looked at whether it was safe to give both jabs together.
Researchers say the results reinforce current coronavirus booster vaccine guidance which is for both jabs to be given together where it is practically possible.
Dr Rajeka Lazarus is consultant in infectious diseases and microbiology at University Hospitals Bristol and Weston NHS Foundation Trust (UHBW) and chief investigator for the ComFluCov study.
She said: “By conducting this study we have been able to establish that it is possible to protect people from both Covid-19 and flu at the same appointment.
“This is a really positive step which could mean fewer appointments for those who require both vaccines, reducing the burden on those who have underlying health conditions and would usually be offered the influenza vaccine.”
Dr Lazarus added: “This is already happening.
“These data have been shared with JCVI and with MHRA to help support the regulations that they’ve already made in preparation for this season.”
Two Covid and three flu vaccines were tested, meaning six combinations in all.
Study participants were over the age of 18 and had already received one dose of either the Pfizer/BioNTech or the Oxford/AstraZeneca jab, and were awaiting their second dose.
A total of 679 volunteers took part in the study across 12 NHS sites in England and Wales.
They were randomly allocated to either receive their second dose of the Covid vaccine and the flu vaccine at their first study visit, then a placebo at their second visit
A second group received their second dose of the Covid-19 vaccine and a placebo at their first visit and then the flu vaccine at their second visit.
Participants also attended a third study visit to discuss any side effects and give a blood sample.
The most common side effects were pain around the injection site and fatigue.
Some combinations saw an increase in the number of people who reported at least one side effect when both Covid-19 and flu vaccine were given together, but the reactions were mostly mild or moderate, researchers found.
According to the study, the immune responses to both the flu and Covid-19 vaccine were preserved when given together, and 97% of participants said they would be willing to have two vaccines at the same appointment in the future.
Professor Andrew Ustianowski, NIHR clinical lead for the Covid-19 vaccination programme and joint national infection specialty lead, said: “This research has quickly provided important and reassuring results that could make vaccination more efficient for both patients and the NHS.”
The study was led by researchers at the Bristol Trials Centre, UHBW, and supported by the Clinical Research Network (CRN) West of England.
It was funded by the National Institute for Health Research (NIHR), with the results due to be published in The Lancet.
The data has been released as a preprint, and has not yet been through peer-review.