In an unusual turn of events, this year's flu shot is exactly the same as last year's, but experts say you should get it again anyway.
The vaccine usually changes annually to combat the three primary forms of the ever-shifting influenza virus circulating that year. You need a new shot because the virus is different enough from its past incarnations that your immune system won't recognize it.
This time, health officials say you need to get another shot because last year's may have worn off.
The American Academy of Pediatrics last week recommended that all children over age six months be vaccinated, even if they had the shot last year. It said immunity can drop by as much as 50 percent six to 12 months after people get the vaccine. The U.S. Centers for Disease Control and Prevention also recommends that everyone who is eligible for the shot get another one.
Children 6 months to 8 years old normally need two doses of vaccine. Kids vaccinated last year will need only one, the academy said.
P.J. Brennan, an infectious- disease specialist and chief medical officer for the University of Pennsylvania Health System, said the recommendations make sense. "Immunity does wane. That's kind of the holy grail of influenza vaccination, finding the right structures to create immunity that's long-lasting so we don't need to go through these annual campaigns."
Robert Bettiker, an infectious-disease doctor at Temple University Hospital, said flu viruses change often enough that long-lasting vaccines haven't been essential, although scientists want to develop vaccines that can cover more flu types.
The vaccine is 90 percent effective in young, healthy adults, but not as effective for very young children, the elderly, or people with compromised immune systems. One argument for vaccinating everyone every year is that it protects the people who are most vulnerable to flu, but also least likely to have a powerful response to the vaccine.
"I'm going to get mine," Bettiker said. "My son, who is 5, is going to get his. He's not thrilled with me."
- Stacey Burling
