No increase in adverse effects after giving COVID-19 and flu vaccine together, data suggest

Researchers report that 97% of participants in the 'Combining influenza and COVID-19 vaccination' study would opt for having two vaccines in the same appointment in the future.
man wearing a face mask, getting a COVID-19 vaccine injection

Preliminary results from a UK trial show that that patients receiving the flu and COVID-19 vaccine at the same time had similar immunity levels and side-effect profiles.

Results collected from 651 participants in the ‘Combining influenza and COVID-19 vaccination’ (ComFluCOV) study show that 77% (254 participants) of those who received both the COVID-19 and flu vaccines at the same time reported one or more side effects within seven days after vaccination. This compared with 75% (239 participants) of those who received only the COVID-19 vaccine at the first visit.

Fatigue was the most commonly reported reaction in both groups, with other symptoms including fever, chills, headache and malaise.

Meanwhile, there was no negative impact on the immune response produced by either vaccine when administered together.

Immunoglobulin levels measured 21 days after receiving either the AstraZeneca or Pfizer/BioNTech vaccines were similar between those who received concomitant flu vaccination or COVID-19 vaccine alone.

After 21 days, seroconversion rates — the development of antibodies after infection — ranged from 89–100% after the Pfizer/BioNTech vaccine and 79–93% after the Oxford/AstraZeneca vaccine, when either co-administered with the flu vaccine or with the COVID-19 vaccine alone.

The study, which has not yet been peer reviewed, was led by researchers at the Bristol Trials Centre, University of Bristol and University Hospitals Bristol and Weston NHS Foundation Trust (UHBW) and funded by the National Institute for Health Research (NIHR), with the results due to be published in The Lancet.

The results follow guidance from the Joint Committee on Vaccination and Immunisation (JCVI), which said that flu vaccinations could be co-administered with COVID-19 booster jabs from September 2021.

In a letter dated 1 July 2021, NHS England said that co-administration of flu and COVID-19 vaccines in the same appointment “will allow more efficient use of resources and a better service for patients, as well as potentially helping to improve uptake of both vaccines”.

In total, 679 patients aged over 18 years took part in the study between April and June 2021 across 12 NHS sites in England and Wales. They were randomly assigned to one of two groups: 340 participants received both their second dose of COVID-19 vaccine and the flu vaccine at their first study visit, followed by a saline injection at their second visit. The second group received their second dose of the COVID-19 vaccine and a saline injection at their first visit and then the flu vaccine at their second visit.

All participants received either the Pfizer/BioNTech or the Oxford/AstraZeneca COVID-19 vaccine, in line with the type of vaccination they received as their first dose, and the flu vaccine recommended for their age group — either the QIVc, aTIV or QIVr vaccines.

All participants also attended a third appointment to discuss any side effects they had experienced following their second appointment and to give a blood sample to test for immune response.

Rajeka Lazarus, consultant in infectious diseases and microbiology at UHBW and chief investigator for the ComFluCOV study, said there was “more uncertainty” around the result for the cohort who had the Pfizer/BioNTech vaccine and the QIVr flu vaccine, owing to a smaller number of participants (58 people).

However, the researchers “can definitely say that there were no safety signals and the current advice is that the combinations can be currently used with the flu vaccines that are being recommended”, she added.

Overall, researchers found 97% of participants said they would be willing to have two vaccines at the same appointment in the future.

Lazarus continued: “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.”

On 28 September 2021, Boots announced that it plans to offer COVID-19 vaccinations and flu vaccinations at the same time “wherever possible”.

READ MORE: COVID-19 booster campaign: everything we know so far

Last updated
The Pharmaceutical Journal, PJ, October 2021, Vol 307, No 7954;307(7954)::DOI:10.1211/PJ.2021.1.107952

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