RIT scientist: Think of the flu shot as an update
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Because the influenza virus mutates and the bodies’ response to the virus wanes, scientists update flu vaccines every year to help fight off infection.
The annual flu vaccine is like a software update for the immune system, a Rochester Institute of Technology expert in biochemistry and microbiology says.
RIT
Andre Hudson
Each year, scientists monitor the changes in the various influenza viruses as it pertains to mutations and update the vaccine to better match the viruses expected to circulate, said Andre Hudson, dean of RIT’s College of Science.
Vaccination gives the immune system a preview and an updated picture of what it may encounter.
“Influenza is a moving target,” said Hudson. “Flu viruses are constantly evolving. As influenza viruses replicate, genetic changes accumulate.”
Hudson said that these changes can alter surface proteins that the immune system recognizes via antibodies, which is called antigenic drift. Over time, drift can make circulating viruses different enough that antibodies generated against earlier strains do not recognize them as effectively.
Scientists around the world monitor influenza to see which strains are circulating and how they are evolving. Surveillance data is used to recommend which flu strains should be targeted in vaccines for each season.
The method isn’t perfect, though, Hudson said. Scientists use predictive modeling, which includes guess work to predict what strains will mutate to. The vaccine also must be ready early in flu season since it is a preventive measure against the illness.
The Centers for Disease Control and Prevention reports that all three virus components in the 2026-2027 U.S. seasonal flu vaccine were updated from the previous season. The organization recognizes December through February as peak flu season.
