Sanofi Investigational COVID-19/Influenza Combination Vaccines Granted FDA Fast-Track Designation

The FDA has awarded fast-track status to 2 investigational Sanofi vaccines that combine previously licensed and authorized vaccines against influenza and COVID-19, according to the vaccine sponsor. The immunizations, pairing shots already proven safe and effective in randomized controlled clinical trials, target prevention of both infections in adults aged 50 years and older.1

The first vaccine combines Sanofi’s Fluzone High-Dose (TIV-HD), an inactivated trivalent vaccine for prevention of influenza types A and B in adults 65 years and older, with the COVID-19 vaccine from Novavax, which is an adjuvanted protein-based recombinant vaccine under the FDA’s Emergency Use Authorization to prevent COVID-19 in persons aged 12 years and older, according to the Sanofi news release.1

The second vaccine is a combination of Sanofi’s Flublok, a recombinant hemagglutinin trivalent vaccine to prevent influenza types A and B in adults 18 years and older, and the Novavax COVID-19 vaccine.

The FDA’s Fast Track designation reflects the potential for the vaccine combinations, if approved, to mitigate the significant burden of the 2 serious illnesses on individuals and families as well as on the health care system. Both infections can lead to hospitalization and can be fatal, particularly among older adults, the company noted.

Sanofi is evaluating the safety and immunogenicity of the 2 novel vaccine duos in 2 separate parallel, randomized, modified double-blind, multiarm phase 1/2 clinical trials that have each enrolled approximately 980 adults aged 50 years and older: Fluzone-HD/Novavax (NCT06695117) and Flublok/Novavax (NCT06695130).1

Both studies will evaluate the combination vaccines using different recombinant spike antigen levels of the Novavax COVID-19 vaccine vs the Fluzone or Flubok influenza vaccine alone, the Novavax COVID-19 vaccine alone, and the Fluzone or Flubok influenza vaccine and the Novavax COVID-19 vaccine coadministered in opposite arms, according to the ClinicalTirals.gov descriptions. In both studies, a placebo injection will be administered in the Flublok or Fluzone-HD alone, Novavax alone, and Flublok or Fluzone plus Novavax combination study groups to control for the number of injections and to maintain blinding.

At enrollment in each study, participants will receive a single intramuscular injection in the right and left deltoid muscle. The study will run for approximately 12 months.

Sanofi cites the findings of a systematic review and meta-analysis conducted midway through the COVID-19 pandemic (2022)2 that suggest use of a combined influenza/COVID-19 booster vaccine could potentially increase uptake of the latter vaccine by more than 56%.2 The company also notes that there may be benefits to health care professionals of using a combination vaccine, including easier and faster administration with fewer injections, potentially fewer administration errors, and reduced disposal requirements for syringes and vials.1

“Our goal is to develop a combined flu and COVID-19 vaccine that offers simpler scheduling and fewer injections without compromising on the industry leading levels of efficacy, safety and tolerability of the standalone vaccines included in our combination vaccine,” Thomas Triomphe, executive vice president of Sanofi, concluded in the press release.1

References
1. Two combination vaccine candidates for prevention of influenza and COVID-19 granted Fast Track designation in the US. News release. Sanofi. December 11, 2024. Accessed December 18, 2024. https://www.sanofi.com/assets/dotcom/pressreleases/2024/2024-12-11-06-00-00-2995072-en.pdf
2. Tzenios N, Tazanios ME, Chahine M. Combining influenza and COVID=19 booster vaccination strategy to improve vaccination uptake necessary for managing the health pandemic: a systematic review and meta-analysis. Vaccines (Basel). 2022;11(1):16. doi:10.3390/vaccines11010016