Millions of Americans are rolling up their sleeves to get one, but a new study claims the flu shot may not be as protective as you think.
The study, published in the Journal "Lancet," found over the last four decades, the shot only kept the flu away from healthy adults about 59 percent of the time.
However, researchers say the nasal spray vaccine for children kept the flu away 83 percent of the time.
"Young adults and older children have the best immune response to the vaccine, and older patients have always had a weaker immune response to the vaccine," Dr. Jahangir Rahman of New York Presbyterian Hospital said.
The Centers for Disease Control recommend everyone over six months old get vaccinated for the flu, and doctors say this new study doesn't change that.
"Besides washing hands and general health care measures, there's nothing else that will prevent influenza short of the vaccine itself," Dr. Rahman said. "This (the flu shot) is your best bet at this time."
While the study shows the nasal spray is very effective for children, the CDC doesn't recommend one flu vaccine over another.