For the First Time, an mRNA Flu Shot Will Be Available to Some People in the United States. Here's What You Should Know

For the first time, the United States will have access to an mRNA flu shot, approved by the FDA on August 5 for adults aged 50 and above. Developed by Moderna, the vaccine uses messenger RNA technology, similar to many COVID-19 vaccines, to teach cells how to produce a harmless viral protein and trigger an immune response. This innovative approach contrasts with traditional flu vaccines, which are developed by predicting circulating strains each year and grown in chicken eggs, a lengthy process that limits flexibility.

Experts, including Georges C. Benjamin of the American Public Health Association, welcome the new vaccine as it could improve public health by allowing rapid adjustments to emerging flu strains. According to a late-stage clinical trial involving nearly 41,000 people published in the New England Journal of Medicine, the mRNA vaccine reduced flu cases by 27% compared to a traditional vaccine and generated stronger immune responses. Additionally, higher antibody levels persisted for six months, suggesting longer protection.

While the NEJM trial deemed the vaccine safe, it also noted a higher frequency of mild to moderate side effects, such as pain at the injection site, fatigue, and headaches. Serious adverse events were rare but included cases of low blood pressure and heart inflammation. The vaccine is currently authorized only for individuals aged 50 and older, who are at higher risk of severe flu complications and account for most flu-related hospitalizations and deaths.

However, the vaccine's availability may be limited due to ongoing litigation blocking the CDC's vaccine advisory committee from convening and issuing recommendations. Without guidance, insurance companies may not cover the new flu shot, potentially restricting public distribution.