FDA Approves Moderna's mRNA Flu Vaccine, mFlusiva, for Older Adults

The Food and Drug Administration has granted approval to the first mRNA-based flu vaccine in the United States, Moderna's mFlusiva, targeting adults aged 50 and above. This landmark decision marks a significant advancement in influenza vaccination, leveraging the same mRNA technology used in Covid-19 vaccines.

Enhanced Effectiveness and Rapid Production

In a late-stage clinical trial, mFlusiva demonstrated approximately 27% greater effectiveness than traditional flu vaccines. This efficacy is attributed to the mRNA technology, which allows for faster production and better alignment with circulating flu strains. Moderna highlights that their mRNA flu vaccine can be manufactured in two to three months, significantly shorter than the six-month timeframe required for conventional vaccines.

Dr. Ofer Levy, director of the Precision Vaccines Program at Boston Children’s Hospital, emphasized the advantages of this rapid production, noting that traditional methods involve selecting flu strains up to six months in advance, which can lead to mismatches.

Regulatory and Clinical Challenges

The FDA's approval comes with a stipulation for Moderna to conduct an additional clinical trial for adults aged 65 and older. This decision follows initial hesitancy from the FDA, which sought more data, as Moderna compared mFlusiva to a standard flu shot rather than a high-dose vaccine typically recommended for this age group by the Centers for Disease Control and Prevention (CDC).

Despite these hurdles, the FDA’s independent vaccine advisory committee unanimously recommended the vaccine in June, following a trial involving over 40,000 older adults across 11 countries. Side effects, such as injection-site pain, fatigue, and headaches, were reported but were mild to moderate.

Availability and Insurance Implications

Moderna plans to release mFlusiva for the upcoming flu season. However, the CDC's Advisory Committee on Immunization Practices (ACIP) has yet to formally recommend it due to a federal injunction preventing the committee from convening. While mFlusiva can still be prescribed without ACIP’s recommendation, insurance coverage may be limited, as insurers typically cover only ACIP-endorsed vaccines. This limitation also affects public programs like Vaccines for Children and Medicaid, which rely on ACIP guidance.

Despite these administrative challenges, the approval of mFlusiva represents a promising development in flu prevention, potentially offering a more adaptable and effective option for older adults.