FDA Approves Moderna mFlusiva mRNA Flu Vaccine

The context

Flu vaccines in the U.S. have been made largely the same way for decades, most commonly by growing virus in eggs, along with cell-culture and recombinant methods. That manufacturing process takes six to eight months, Vox reported, which means the flu strains circulating by the time flu season arrives often differ from the ones the vaccine was designed against. mRNA vaccines work differently, delivering genetic instructions that teach cells to build viral proteins the immune system learns to recognize, and they can be produced faster and closer to flu season.

The path to approval was contested. In February, FDA official Vinay Prasad refused to review the vaccine over objections from agency staff, arguing Moderna had compared it to the wrong existing vaccine, Ars Technica reported. Moderna pushed back publicly, saying the FDA had previously signed off on its trial designs. The agency reversed the decision a week later, and Prasad left the FDA at the end of April. Kennedy, meanwhile, has called the mRNA COVID-19 vaccine the "deadliest vaccine ever made" and canceled hundreds of millions of dollars in mRNA research grants, according to Ars Technica.

Why it matters

Influenza is one of the most common vaccine-preventable illnesses in the U.S., and tens of millions of Americans get flu shots each year. Vox reported the disease causes roughly 1 billion infections and 300,000 deaths globally each year. A vaccine that is up to 27 percent more effective than the current standard could improve protection for older adults, who face the highest risk. The approval also validates the mRNA platform beyond COVID-19; researchers are developing mRNA vaccines against malaria, tuberculosis and HIV, and public health officials see this clearance as a signal the technology could target a wider range of diseases.

What’s next

Moderna must conduct a further clinical trial of mFlusiva in adults 65 and older as a condition of the approval, Scientific American reported. It remains unclear when the vaccine will be available or how it will be priced, and whether the approval could later extend to adults under 50. Researchers continue to pursue a universal flu vaccine, defined as one at least 75 percent effective against influenza A with protection lasting at least a year, according to Vox.