It is safe to have a flu vaccination at the same time as a second dose of a Covid-19 vaccine, according to a pre-print of a study with The Lancet. The co-administration of the vaccines raises no safety concerns and preserves the immune response to both vaccines, the study concluded.

The study, carried out at University Hospitals Bristol and Weston NHS Foundation Trust, was funded by the Department of Health in light of the potential need to administer Covid-19 booster jabs alongside seasonal flu vaccines.

Over 670 adults who had been given a single dose of either the Pfizer of AstraZeneca Covid-19 vaccine were enrolled at 12 UK sites and randomised 1:1 to receive concomitant administration of either an age-appropriate flu jab or placebo alongside second Covid-19 vaccine.

Three weeks later the group who received placebo received the influenza vaccine, and vice versa. Participants were followed up for six weeks.

Most reported side effects were mild or moderate and were similar between the randomised groups. Immune responses were not adversely affected.