Is the 2025 influenza vaccine an mRNA (messenger ribonucleic acid) vaccine?

2025 Flu Vaccines Are Not mRNA Vaccines

The 2025 influenza vaccines available in the United States are NOT mRNA vaccines, but rather consist of traditional trivalent vaccine formulations including egg-based, cell culture-based, and recombinant options. 1

Available Influenza Vaccine Types for 2024-2025 Season

The CDC and Advisory Committee on Immunization Practices (ACIP) have clearly outlined the available influenza vaccines for the 2024-2025 season:

1. Inactivated Influenza Vaccines (IIV3) - Traditional egg-based vaccines 1
2. Cell Culture-Based Inactivated Vaccines (ccIIV3) - Manufactured using cell culture rather than eggs 1
3. Recombinant Influenza Vaccine (RIV3) - Produced using recombinant technology without eggs or influenza viruses 1
4. Live Attenuated Influenza Vaccine (LAIV3) - Nasal spray containing weakened live viruses 1

Composition of 2024-2025 Influenza Vaccines

All 2024-2025 seasonal influenza vaccines for the United States are trivalent (containing three virus strains) and include:

For egg-based vaccines:

• A/Victoria/4897/2022 (H1N1)pdm09-like virus
• A/Thailand/8/2022 (H3N2)-like virus
• B/Austria/1359417/2021 (Victoria lineage)-like virus 1

For cell culture-based and recombinant vaccines:

• A/Wisconsin/67/2022 (H1N1)pdm09-like virus
• A/Massachusetts/18/2022 (H3N2)-like virus
• B/Austria/1359417/2021 (Victoria lineage)-like virus 1

mRNA Influenza Vaccines: Current Status

While mRNA technology is being explored for influenza vaccines, these are still in development and clinical trials:

• Several mRNA and self-amplifying RNA flu vaccines are currently in clinical or preclinical trials 2
• A Phase 3 trial of mRNA-1010 (a quadrivalent mRNA influenza vaccine) has shown promising results but is not yet approved for general use 3
• A trivalent mRNA vaccine candidate has demonstrated higher immunogenicity compared to inactivated split influenza vaccines in animal studies 4

Effectiveness of Current Influenza Vaccines

Interim estimates for the 2024-2025 season show that the current non-mRNA vaccines are effective:

• Among children and adolescents: 32-60% effective against outpatient influenza and 63-78% effective against hospitalization
• Among adults: 36-54% effective against outpatient influenza and 41-55% effective against hospitalization 5

Important Considerations

• Annual vaccination is recommended for all persons aged ≥6 months as long as influenza viruses continue to circulate 1
• No egg allergy concerns: Evidence shows that individuals with egg allergy can safely receive influenza vaccines without additional precautions 1
• Vaccination timing: September is an appropriate time for vaccination for the upcoming influenza season 6

While mRNA technology shows promise for future influenza vaccines with potential advantages in manufacturing speed and adaptability 7, 2, the 2025 influenza vaccines currently authorized and available in the United States do not use mRNA technology.