Flu activity is climbing earlier than usual this year, according to the Centers for Disease Control and Prevention, but health experts say it is not too late to get vaccinated. For adults 50 and older, several vaccines are available, including one that is new this season.
Dr. Ann Falsey, who teaches infectious diseases at the University of Rochester School of Medicine, discussed the options in an interview with NPR host Ayesha Rascoe. The new shot is built on the same mRNA technology used in COVID-19 vaccines. Falsey described it as giving the body a message so it can make a protein itself and mount an immune response to it. Traditional vaccines instead give the body a piece of the virus to react to.
Speed is a major difference between the two approaches. Conventional flu vaccines are grown in chicken eggs or in cells, and manufacturers must predict which strains will circulate in winter. That means starting six to nine months ahead. With mRNA, Falsey said, makers can choose the protein to target and produce the vaccine much more quickly. That allows them to adapt to a new strain and scale up production to supply more doses sooner.
Early evidence points to a benefit. Falsey said the first study was published recently and found the mRNA vaccine was about 27% more effective than a standard-dose flu vaccine.
The shot is limited to people 50 and older because that is the group in which it was studied, and the FDA approves a vaccine only for the people included in the research. Falsey noted that this age group is also at higher risk of serious illness from influenza. She said mRNA vaccines carry slightly more reactogenicity, so recipients might have a sore arm or feel "a little punky" the next day. In her words, it is always a trade-off. She indicated the vaccine would work in younger people too, but older adults are the priority.
Falsey also addressed worries about mRNA technology. She said it was a misconception that these vaccines were brand new during the COVID pandemic, since researchers had worked on RNA vaccines for a couple of decades. She encouraged skeptical people to name their specific concern. To those who fear the vaccine could integrate into their DNA, she said she could state with 100% certainty that it will not happen. She added that much more time has passed since the COVID shots arrived, giving researchers more data.
Falsey does not expect mRNA to replace protein-based vaccines. Some people simply never want an RNA product, she said, so options will remain important. Older adults can already choose a high-dose vaccine made with protein in traditional eggs, a vaccine with an adjuvant that gives the immune system an extra boost, or a higher-dose cell-based vaccine.
For people ages 50 to 64, the high-dose and adjuvanted vaccines are not approved. Falsey said the new mRNA shot could be an option for those in that group who want some extra protection.
