FDA approves Moderna flu vaccine after spat with past agency leaders

The US Food and Drug Administration (FDA) has finally approved Moderna's mRNA seasonal flu vaccine, known as mFlusiva or mRNA-1010, after initially refusing to review the application. The immunization, which is effective against four common strains of influenza, has been in human testing since 2021. According to the World Health Organization (WHO), these variants cause up to five million severe flu cases and 650,000 respiratory deaths annually.

Moderna's vaccine is approved for adults aged 50 and over, with accelerated approval for those aged 65 and older. The Phase 3 clinical trial, which enrolled 40,805 adults across 11 countries, aimed to evaluate the safety and relative efficacy of mFlusiva compared to an approved non-mRNA vaccine. Researchers found that mFlusiva was superior to standard-dose licensed vaccines for preventing influenza-like illness in adults 50 years of age or older.

However, it also noted that solicited adverse events were more frequent with mRNA-1010, including injection-site pain, fatigue, headache, and muscle pain. Most reactions were mild to moderate and transient.

The FDA's decision to approve mFlusiva came after a rocky start, with the agency initially rejecting the application due to concerns about the comparator vaccine used in the trial. Critics accused the FDA of rejecting conventional science to serve a predetermined anti-vaccine agenda. However, the FDA later reversed its decision and approved the vaccine, likely after confirming that the selected comparator vaccine was acceptable.

Moderna's mRNA vaccines have generally fared well in trials due to their inherent properties, such as high efficacy, rapid development times, adaptability to new strains, and fewer side effects for immunocompromised individuals.