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October 2021

Study confirms COVID and flu vaccines can be co-administered

The long-awaited results of the ComFluCOV study have confirmed that co-administration of flu vaccine and a second dose of COVID-19 vaccine is safe and preserves the immune response to both vaccines.

The study’s findings have already been presented to the Joint Committee on Vaccination and Immunisation (JCVI) and are reflected in current advice that both vaccinations can be given together (Practice Nurse September 2021).

ComFluCOV included around 680 subjects, all aged over 18, who had already had one dose of either the Pfizer-BioNTech or Oxford-Astra Zeneca COVID vaccinations. Subjects included people who were pregnant, in a clinical risk group, immunocompromised or aged 65 years or over, to represent the population most likely to be eligible for both vaccines.

Participants were randomised to receive either a flu vaccine or placebo in the opposite arm to their second COVID vaccine, then switched to the opposite group 3 weeks later. They then re-attended to provide a blood sample to test for immunogenicity and to discuss any adverse effects.

The most commonly reported side effects were pain at the injection site and fatigue, with a slight increase in these effects when the two vaccines were administered together. However, reactions were generally mild to moderate. Immune responses to both vaccines were preserved when co-administered.

The JCVI has advised that practices should offer flu and COVID vaccines as soon as patients become eligible rather than waiting for deliveries of either vaccine to administer them at the same time.

Lazurus R, et al. Lancet preprint, available at

Practice Nurse 2021;51(9):7