Sanofi US News

Positive results from the first study of high-dose quadrivalent influenza vaccine with a COVID-19 mRNA booster support co-administration recommendations
First study to investigate the safety and immunogenicity of both vaccines when co-administered compared to each vaccine administered separately in adults aged 65 years and older
Timely new data for the start of the influenza vaccination campaigns across the Northern Hemisphere

7 October 2021

Interim results from the first co-administration descriptive study of Sanofi’s Fluzone® High-Dose Quadrivalent (Influenza Vaccine) with Moderna’s COVID-19 mRNA investigational booster vaccine 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 the only vaccine approved by the U.S. FDA for superior flu protection in adults 65 years of age and older, compared to a standard-dose flu vaccine. In addition, Fluzone High-Dose (Influenza Vaccine) has demonstrated protection against influenza and its related complications including cardiorespiratory events, pneumonia and hospitalization.

“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, including the US, France, the UK and Germany.

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 (100mcg 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
Fluzone High-Dose Quadrivalent is a vaccine indicated for prevention of influenza disease caused by influenza A and B strains contained in the vaccine. Fluzone High-Dose Quadrivalent is given to people 65 years of age and older.

Fluzone High-Dose Quadrivalent is the only vaccine approved by the U.S. FDA for superior flu protection in adults 65 years of age and older, compared to a standard-dose flu vaccine.  With 4-strain protection, Fluzone High-Dose Quadrivalent builds on the legacy of the trivalent formulation, which was clinically proven to be 24.2% more effective at preventing flu than standard-dose Fluzone (Influenza Vaccine) in adults 65+. Based on data from Fluzone High-Dose (Influenza Vaccine), side effects were slightly more frequent after vaccination with Fluzone High-Dose compared to a standard-dose vaccine.

In addition, Fluzone High-Dose has demonstrated protection against influenza and its related complications including cardiorespiratory events, pneumonia and hospitalization.

The efficacy of trivalent formulation is relevant to Fluzone High-Dose Quadrivalent since both products are manufactured according to the same process and have overlapping compositions.


Fluzone High-Dose Quadrivalent should not be given to anyone who has had a severe allergic reaction to any component of the vaccine, including eggs or egg products, or after previous dose of any influenza vaccine.

Tell your health care provider if you have ever had Guillain-Barré syndrome (severe muscle weakness) after a previous influenza vaccination.

If Fluzone High-Dose Quadrivalent is given to people with a compromised immune system, including those receiving therapies that suppress the immune system, the immune response may be lower than expected.

Vaccination with Fluzone High-Dose Quadrivalent may not protect all people who receive the vaccine.

For Fluzone High-Dose Quadrivalent, in adults 65 years of age and older, the most common side effects were pain, redness, and/or swelling where you got the shot; muscle ache, headache, and general discomfort. Other side effects may occur.

Please see the Prescribing Information, including Patient Information Sheet.

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.


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