Should flu vaccination be recommended alongside a COVID booster vaccine and can these be delivered together?

18 Aug 2021

What the research says:

Coinfection with influenza and SARS-CoV-2 is associated with an increased risk of severe disease and adverse outcomes. Influenza vaccination has been shown to confer benefits in terms of improved outcomes for those with COVID-19 illness (Thindwa et l 2020; Wang et al 2021).

Studies are ongoing to evaluate the effectiveness and safety of delivering SARS-CoV-2 and influenza vaccinations at the same time. A sub-study of the Phase 3 trial of the NVX-CoV2373 vaccine has shown that coadministration with influenza vaccine is safe, stimulates an immune response against SARS-CoV-2 and was effective in terms of preventing symptomatic COVID-19 illness (Toback et al 2021). Early results from the ComFluCOV study in the UK ( suggest no increase in side effects and full results are expected August/September 2021.

Different countries appear to be taking different approaches for the delivery of a combined influenza and SARS-CoV-2 booster vaccination programme. For example, the UK has approved delivery of both vaccines on the same day while in Australia the recommendation is to wait 7 days between getting the flu and COVID-19 vaccines (, although they acknowledge that there’s no evidence that the 2 vaccines interact and the recommendation is precautionary.

What this means for your clinical practice:

  • Continue to deliver vaccination against influenza according to National guidelines
  • Continue to deliver vaccination against SARS-CoV-2 according to National guidelines. For patients receiving a dual-dose SARS-CoV-2 vaccine, continue to emphasise the need to receive both doses due to the increased vaccine effectiveness, especially against the Delta variant, after the second dose
  • There is currently no evidence to suggest that giving flu and SARS-CoV-2 (first or second dose) vaccines on the same day or 7 days apart is associated with reduced effectiveness or increased risk for side effects
  • Waiting 7 days between doses of seasonal flu vaccine and the COVID-19 vaccine, is a reasonable precautionary measure that allows monitoring and management of the common side effects that come with many vaccinations
  • High prevalence of either infection in the population might mean a more rapid dual approach is required and certain communities that are hard to reach either due to geography or availability may also require a more pragmatic dual delivery approach

Useful links and supporting references:

Lopez Bernal J, et al. Effectiveness of COVID-19 vaccines against the B.1.617.2 (Delta) variant. NEJM 2021. Available at: Accessed August 2021.

Thindwa D, et al. Use of seasonal influenza and pneumococcal polysaccharide vaccines in older adults to reduce COVID-19 mortality. Vaccine 2020;38:5398–401. Available at: 10.1016/j.vaccine.2020.06.047. Accessed August 2021.

Toback S, et al. Safety, immunogenicity, and efficacy of a COVID-19 vaccine (NVX-CoV2373) co-administered with seasonal influenza vaccine. Pre-print. Available at: Accessed July 2021.

Wang R, et al. The associated between influenza vaccination and COVID-19 and its outcomes: A systematic review and meta-analysis of observational studies. Vaccines 2021;9:529. Available at: 10.3390/vaccines9050529. Accessed August 2021.


Dr Osman Yusuf (Chief Consultant of the Allergy & Asthma Institute, Pakistan) for and on behalf of the IPCRG practice driven answers review group.

Resource information

Respiratory conditions
  • COVID-19
  • Respiratory Infection
Respiratory topics
  • Vaccination
Type of resource
IPCRG COVID-19 and respiratory Q&A