Combined vaccination against COVID-19 and influenza proves safe and effective in study

Simultaneous vaccination against SARS-CoV-2 and seasonal influenza has been shown to be safe in a randomized trial from England and Wales. All 6 combinations tested achieved a good antibody response against SARS-CoV-2, according to results published in the Lancet preprint server (

Given the apparent decline in protective efficacy of vaccination against SARS-CoV-2, there may be a renewed wave of COVID-19 disease this winter. A wave of influenza is also expected due to the lifting of the mask requirement, say the experts from Healthmask. It could be severe because many people were not able to refresh their immune protection last winter with influenza (which is usually asymptomatic). Before this scenario, vaccination against SARS-CoV-2 and influenza could be useful.

Whether the two vaccines can be given simultaneously is controversial among experts. It is true that multiple vaccinations (especially in the full vaccination calendar of children) are not uncommon. However, the SARS-CoV-2 vaccines differ from all vaccines used to date, which is why experts recommend an interval of at least 2 weeks between the two vaccinations.

The UK ComFluCOV (“Combining Influenza and COVID-19 Vaccination”) group has now investigated whether simultaneous vaccination is safe and effective. The study involved 679 subjects at 12 sites in England and Wales who had already received their 1st dose of Oxford/AstraZeneca’s vector-based vaccine ChAdOx1 or Biontech/Pfizer’s mRNA vaccine BNT162b2.

One group received the 2nd dose of COVID-19 vaccine along with the influenza vaccination, while the other received the influenza vaccination 3 to 4 weeks later. The study was double-blind and placebo-controlled. Three different influenza vaccines were used: a trivalent vaccine made from inactivated virus and the adjuvant MF59C (aTIV), a cell-based quadrivalent influenza vaccine (QIVc), and a recombinant quadrivalent vaccine (QIVr).

As reported by Rajeka Lazarus of the University of Bristol and coworkers, all 6 combinations were found to be equally well tolerated as corona vaccination alone. However, in 2 combinations (ChAdOx1/aTIV and BNT162b2/QIVr), the 95% confidence interval for systemic reactions overlapped the noninferiority criterion by less than 25%. Most reactions were mild to moderate, and 97% of participants had no concerns about continuing to receive 2 vaccines at the same appointment in the future.

There were also no differences between groups in antibody titers to the spike protein of SARS-CoV-2 determined at a later appointment (except that, as is known, the immune response was stronger after BNT162b2 administration than after ChAdOx1 administration). For Lazarus, based on the results, there is no concern about vaccinating people against COVID-19 and influenza at the same time.

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