Influenza virus. 3D illustration showing surface glycoprotein spikes hemagglutinin purple and neuraminidase orange

[Image courtesy of Adobe Stock]

mRNA technology helped propel the development of some of the most successful drugs in pharma history — notably, the Comirnaty COVID-19 from Pfizer generated almost $56 billion in 2022 while Moderna’s Spikevax vaccine raked in $18.4 billion. But with demand for COVID-19 vaccines cooling, drug developers are aiming to extend the dominion of mRNA technology to flu vaccines. This month, Moderna and the CureVac/GSK alliance announced promising interim results for their respective flu vaccine candidates. Meanwhile, a year ago, in September 2022, Pfizer announced a phase 3 study for its mRNA-based influenza vaccine. NIH is also developing an mRNA vaccine that promises to provide protection against all known influenza subtypes. A phase 1 study of it is underway.

Sanofi has acknowledged the promise and perils of mRNA flu vaccines

Sanofi, a prominent flu vaccine maker, has acknowledged both the challenges and the potential of mRNA technology for flu. In a presentation earlier this year, the company shared market research noting that health care professionals will likely be reluctant to adopt mRNA-based flu vaccines with storage requirements more stringent than standard refrigeration. Additional market research notes that just under 70% of health care providers and patients would be unlikely to use mRNA vaccines with triple the severe side effect burden compared to a standard dose of traditional flu vaccine.

HCPs and consumers are unlikely to use vaccines with3x severe side effect burden compared to Standard Dose

Graphic showing health care providers (HCPs) and consumers’ reluctance toward vaccines with three times as many severe side effects compared to the standard of care flu vaccine. Source: Sanofi Company Presentation.

Despite challenges, Sanofi is moving ahead with mRNA vaccines. They company’s phase 1/2 studies for mRNA flu vaccines have yielded strong immune responses, especially against A strains, although less so for B strains. In particular, Sanofi’s SP0273 vaccine showed favorable reactogenicity compared to other mRNA candidates in the same age group (18 to 64 years old). The company also is using machine learning to enhance antigen design and optimize strain selection. Initial results are promising, especially for H3 and H1 strains.

In addition to mRNA-based vaccine designs, Novavax is developing a next-generation flu vaccine, qNIV (NanoFlu), using a different approach. The company’s quadrivalent nanoparticle vaccine, which targets seasonal flu using recombinant technology, has successfully completed two phase 3 studies.

Company/Organization Vaccine Name/ID Description/Details Phase & Study Details Strains Covered (if specified)
Moderna mRNA-1010 An mRNA-based flu vaccine designed to elicit a robust immune response against flu strains.
  • Phase 3 (P303) clinical study interim analysis announced on September 13, 2023.
  • Met all co-primary endpoints for A and B strains.
  • Higher Hemagglutination Inhibition (HAI) geometric mean titers and seroconversion rates than Fluarix, a licensed quadrivalent influenza vaccine.
  • Improved immunogenicity across all age groups.
  • Consistent adverse reactions with previous studies.
 A/H1N1, A/H3N2, B/Yamagata, B/Victoria
National Institutes of Health (NIH) H1ssF-3928 mRNA-LNP An experimental universal influenza vaccine developed by NIAID’s Vaccine Research Center. Universal
CureVac (with GSK) CVSQIV mRNA-based seasonal flu vaccine candidate based on an advanced mRNA backbone. Broad coverage against WHO-recommended flu strains
Pfizer (in collaboration with BioNTech) Quadrivalent modRNA influenza vaccine mRNA-based influenza vaccine candidate with potential for rapid manufacturing, flexibility, and improved strain match.
  • Launched phase 3 study on September 14, 2022.
  • Pfizer hailed the trial as the first Phase 3 efficacy study for an mRNA-based influenza vaccine.
  • Enrolling approximately 25,000 healthy U.S. adults 18 years and older.
  • Study informed by data from the ongoing Phase 2 trial which demonstrated a promising safety and immunogenicity profile.
 Strains recommended by WHO for the Northern Hemisphere 2022-23 cell culture- or recombinant-based influenza vaccines.
Sanofi MRT5400 & MRT5401 Experimental mRNA-based influenza vaccine by one of the world’s largest vaccine makers.
  • Early-stage human testing showed a strong immune response against A strains but was ineffective against the less prevalent B strains.
  • Sanofi is working on the next generation of mRNA technology to overcome current challenges.
  • Focus on a better immune response against B strains, improved lipid encapsulation of mRNA molecules, and longer stability at regular fridge temperatures.
 Initial prototypes were more successful for A strains than B strains.