Positive results from the first study of high-dose influenza vaccine with a COVID-19 mRNA booster support co-administration recommendations

Alternative Medicine

SanofiInterim results from the first co-administration descriptive study of Sanofi’s Fluzone® High-Dose Quadrivalent vaccine with Moderna’s COVID-19 mRNA investigational booster dose show that the administration of the vaccines at the same visit had similar immunogenicity responses and a similar safety and tolerability profile compared to each vaccine administered individually.

Fluzone® High-Dose Quadrivalent is a high-dose quadrivalent influenza vaccine, indicated for adults aged 65 and older in the United States and Canada. It is also licensed under the brand name Efluelda® in Europe where it is indicated for adults aged 60 and older. Fluzone High-Dose is the only influenza vaccine that has demonstrated reductions in influenza-related complications such as hospitalizations due to cardiovascular events and pneumonia, over 10 consecutive seasons in more than 34 million people aged 65 and older(1,2,3).

“This season, more than ever, it is critical to help protect the older adults, who are at especially high risk for both severe COVID-19 and complications from influenza, which can include heart attacks and strokes,” says Dr. Michael Greenberg, North America Medical Head for Vaccines at Sanofi. “This is the first study to provide supportive evidence for vaccinating against influenza at the same time as a COVID-19 mRNA booster in seniors. These positive results could facilitate the implementation of Northern Hemisphere influenza and COVID-19 booster vaccination campaigns, especially in this high-risk population.”

These encouraging results reinforce existing co-administration recommendations across the world. Concomitant use of COVID-19 vaccines and influenza vaccines is currently permissible in several countries(4), including the US(5), France(6), the UK(7) and Germany(8).

About the study

This descriptive study is being conducted in the United States and is currently following participants for 6 months for safety. It includes around 300 participants aged 65 years of age and older who received two doses of a COVID-19 mRNA vaccine as primary vaccination at least five months prior to enrollment. The study assesses the safety profile and immune response when COVID-19 mRNA investigational booster vaccine (100 mcg dose) and high-dose quadrivalent influenza vaccine are administered simultaneously. Full results of the study will be published later this year.

The study is sponsored by Sanofi, in partnership with the Biomedical Advanced Research and Development Authority (BARDA), part of the office of the Assistant Secretary for Preparedness and Response at the U.S. Department of Health and Human Services, and with Moderna.

The COVID-19 mRNA vaccine (mRNA-1273 vaccine, 100mcg) evaluated in this study is produced by Moderna and administered as a booster at the 100 mcg dose level. Study participants previously received a primary series of Moderna’s COVID-19 vaccine (two doses) at least five months prior to enrollment. An application by Moderna for a booster indication is currently under review by the U.S. FDA.

About Fluzone® High-Dose Quadrivalent / Efluelda®

Fluzone® High-Dose Quadrivalent is a high-dose quadrivalent influenza vaccine, indicated for adults aged 65 and older in North America. It is also licensed under the brand name Efluelda® in Europe where it is indicated for adults aged 60 and older.

This high dose influenza vaccine was first developed and licensed in trivalent formulation in the United States in 2009 for people aged 65 and older. The data from the trivalent formulation are inferred to the quadrivalent formulation after the completion of an immunogenicity study(9,10).

This high dose influenza vaccine is the first and only influenza vaccine proven superior to standard-dose influenza vaccine for the prevention of influenza in adults 65 years of age and older(11,12), who are a major at-risk group for severe COVID-19 and influenza. This vaccine has demonstrated protection beyond flu with a reduction of influenza-related complications such as hospitalizations due to cardiovascular events and pneumonia consistently during 10 influenza seasons in more than 34 million people aged 65 and older(1,13).

About Sanofi

Sanofi is dedicated to supporting people through their health challenges. We are a global biopharmaceutical company focused on human health. We prevent illness with vaccines, provide innovative treatments to fight pain and ease suffering. We stand by the few who suffer from rare diseases and the millions with long-term chronic conditions.

With more than 100,000 people in 100 countries, Sanofi is transforming scientific innovation into healthcare solutions around the globe.


1. Chang LJ, et al. (2019). Safety and Immunogenicity of High-Dose Quadrivalent Influenza Vaccine in Adults ≥65 Years of Age: A Phase 3 Randomized Clinical Trial. Vaccine. 2019 Sep 16;37(39):5825-5834. doi: 10.1016/j.vaccine.2019.08.016.
2. U.S. Food and Drug Administration (FDA). (2020). Package Insert – Fluzone High-Dose Quadrivalent. Sanofi Pasteur. Available at: https://www.fda.gov/ media/132238/download. Accessed May 2020.
3. J.K H Lee, G.K.L Lam, T. Shin et al, Efficacy and effectiveness of high-dose influenza vaccine in older adults by circulating strain and antigenic match: An updated systemic review and meta-analysis, Vaccine, https://doi.org/10.1016/j.vaccine.2020.09.004
4. As of September 30th: Austria, Belgium, Canada, Denmark, Estonia, Finland, France, Germany, Ireland, Latvia, Switzerland, the UK, and the USA
5. US CDC. Interim Clinical Considerations for Use of COVID-19 Vaccines Currently Authorized in the United States (updated 14 May) 2021. Accessed June 2021.
6. Haute Autorité de Santé. Avis n° 2021.0069/AC/SESPEV du 23 septembre 2021 du collège de la Haute Autorité de santé venant compléter l’avis du 23 août 2021 relatif à la définition des populations à cibler par la campagne de rappel vaccinal chez les personnes ayant eu une primovaccination complète contre la Covid-19. 2021; https://www.has-sante.fr/jcms/p_3288556/fr/avis-n-2021-0069/ac/sespev-du-23-
septembre-2021-du-college-de-la-haute-autorite-de-sante-venant-completer-l-avis-du-23-aout-2021-
relatif-a-la-definition-des-populations-a-cibler-par-la-campagne-de-rappel-vaccinal-chez-les-personnesayant-eu-une-primovaccination-complete-contre-la-covid-19. Accessed 30/09/2021.
7. Joint Committee on Vaccination and Immunisation (JCVI). JCVI statement regarding a COVID-19 booster vaccine programme for winter 2021 to 2022. 2021; https://www.gov.uk/government/publications/jcvi-statement-september-2021-covid-19-booster-vaccine-programme-for-winter-2021-to-2022/jcvi-statement-regarding-a-covid-19-booster-vaccine-programme-for-winter-2021-to-2022#:~:text=In%20JCVI%20’s%20view%2C%20the,and%20to%20protect%20the%20NHS. Accessed 17/09/2021.
8 Standing Committee on Vaccination (STIKO) Germany. STIKO-Empfehlung zur COVID-19-Impfung. 2021; https://www.rki.de/DE/Content/Infekt/EpidBull/Archiv/2021/39/Art_01.html;jsessionid=3D09AE10507D6 3C7D0E8BEA75C7986BD.internet102. Accessed 27/09/2021.
9. Chang LJ, et al. (2019). Safety and Immunogenicity of High-Dose Quadrivalent Influenza Vaccine in Adults ≥65 Years of Age: A Phase 3 Randomized Clinical Trial. Vaccine. 2019 Sep 16;37(39):5825-5834. doi: 10.1016/j.vaccine.2019.08.016.
10. U.S. Food and Drug Administration (FDA). (2020). Package Insert – Fluzone High-Dose Quadrivalent. Sanofi Pasteur. Available at: https://www.fda.gov/ media/132238/download. Accessed May 2020.
11. Diaz Granados CA, Dunning AJ, Kimmel M, et al. Efficacy of high-dose versus standard-dose influenza vaccine in older adults. N Engl J Med 2014; 371: 635-645
12. Chang L-J, Meng Y, Janosczyk H, et al. Safety and immunogenicity of high-dose quadrivalent influenza vaccine in adults ≥65 years of age: A phase 3 randomized clinical trial. Vaccine 2019; 37: 5825-5834
13. J.K H Lee, G.K.L Lam, T. Shin et al, Efficacy and effectiveness of high-dose influenza vaccine in older adults by circulating strain and antigenic match: An updated systemic review and meta-analysis, Vaccine, https://doi.org/10.1016/j.vaccine.2020.09.004

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