ComFluCov [COVID-19] [UPH]

  • Research type

    Research Study

  • Full title

    A single-blind, phase IV UK multi-centre randomised controlled trial to determine reactogenicity and immunogenicity of COVID-19 vaccines administered concomitantly with seasonal influenza vaccine



  • Contact name

    Rajeka Lazarus

  • Contact email

  • Sponsor organisation

    R&I UHBW

  • Eudract number


  • ISRCTN Number


  • Duration of Study in the UK

    0 years, 5 months, 3 days

  • Research summary

    Summary of Research
    Mass vaccination against COVID-19 started in the UK in early December 2020 and is likely to continue until mid-2021. Whilst rates of COVID-19 infection have decreased, the emergence of variants of interest and planned easing of lockdown measures has led to predictions of potential resurgence of infection from autumn 2021. The duration of protection of the current COVID-19 vaccines is unknown but it may be that further booster doses will be required in 9 to 12 months’ time with current or potentially strain-modified vaccines to afford continued protection into the autumn. The timing of the booster doses is likely to coincide with seasonal influenza vaccination, which is usually September to February. Delivering COVID-19 and influenza vaccines at separate appointments will cause significant logistical challenges therefore it would be desirable to immunise with both vaccines at the same appointment, in different arms.

    The ComFluCOV trial will determine the safety, as well as the immune responses, to administration of the currently approved COVID-19 vaccines at the same time as the recommended influenza vaccines from the 2020/21 season.

    Participants who are having their second COVID-19 vaccine will be randomised into two groups; one group will receive the influenza vaccine and the other group will receive saline (placebo) at the same time as the COVID-19 vaccine. Participants will not know whether they receive the influenza vaccine or the placebo. After 3 weeks participants who received the influenza vaccine will receive the saline injection and participants who received the saline injection will receive the influenza vaccine. Participants will be followed up for a further 3 weeks after the second injection. We hope to recruit 504 participants into the trial. The trial will be conducted in at least 5 UK NHS centres. The trial is expected to take about 6 months to complete.

    Summary of Results
    : Study Aims Vaccines against COVID-19 have saved many lives, but further booster doses will be needed to give continued protection. With the challenges of immunising large numbers of people against COVID-19 and the need to continue the seasonal influenza (flu) vaccination schedule, it would be preferable for COVID-19 and flu vaccines to be given together at the same appointment.
    The aim of the study was to see what side effects, such as fever and tiredness, people get when they are given their second dose of the COVID-19 vaccine at the same time as the currently recommended flu vaccines. We also looked at people’s immune responses to both vaccines when given together.

    Study Design
    Participants were randomly allocated into one of two groups to make sure it was a fair comparison. Participants attended 3 study visits, each 3-4 weeks apart. Participants completed electronic diaries to report injection site reactions and general side effects following visits 1 and 2. Blood and saliva samples were collected from participants at visits 1, 2 and 3 to measure immune responses.

    The two groups were made up of people with similar characteristics (e.g., age range, number of men and women). The most common side effects in both groups were pain at the vaccination site and tiredness. These were mainly mild or moderate. More people experienced side effects when the two vaccines were given together than when the two vaccines were given separately, but the difference between the groups was small and considered acceptable. Giving the flu and COVID-19 vaccines together did not affect the immune responses to either vaccine. Most participants (97%) were willing to receive two vaccines on the same day in the future. Very few participants in work (3%) took time off work due to vaccine side effects. The numbers were similar in both groups.

    The ComFluCOV study has shown that there are no safety concerns when COVID-19 and flu vaccines are given at the same time. The side effects of giving both vaccines together were generally well tolerated and acceptable. The immune responses show that the vaccines continue to provide protection against flu and COVID-19 when they are given together. The results of this study have informed the COVID-19 booster and seasonal flu vaccination programme in the UK for 2021/22.
    Published results:

  • REC name

    South Central - Berkshire Research Ethics Committee

  • REC reference


  • Date of REC Opinion

    17 Mar 2021

  • REC opinion

    Favourable Opinion

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