The vaccine is covered by insurance carriers and only costs about $30 out of pocket. But only about half of all children are immunized.
Advocacy efforts by the nonprofit organization Families Fighting the Flu were part the gradual change of the CDC recommendation toward universal immunization.
About 100 American children die each year from the flu, according to its executive director, Laura Scott. "It's devastating."
"The more people who get vaccinated, the less disease there is that spreads," said Scott. "You can build a cocoon around your family. Even if you don't have the infant vaccinated, you still have to vaccinate everyone around that baby."
Julie Moise of Kansas City, Mo., lost her 7-month-old son Ian to the flu in 2003. He got sick just 10 days after he had received his first of two flu shots. Her other children had full doses of the vaccine and never got sick.
Moise, a 41-year-old flight attendant, said she was initially "unconcerned" when Ian was diagnosed with the flu by his pediatrician. But by the end of the first day, he was "panting." The doctor reassured her that was normal in a child with a fever.
"His panting turned into more of a sigh and I thought that was a good thing," said Moise. "But later the doctor told me that happens when people's organs are shutting down."
Moise, too, was bedridden with the flu and called her husband to come home from work and help. She called the doctor's office again.
"Glen walks in the door and the phone rings -- it's the nurse," she said. "He told her, 'I don't like his coloring, let's take him to the emergency room.' Then Ian stopped breathing."
Moise, who is trained in CPR, attempted to save Ian while they rushed to the ER. They stopped at a nearby fire station and rescue workers also tried unsuccessfully to revive the baby. He died that afternoon at the hospital.
"The message is: First of all, take the flu seriously," she said. "We didn't think healthy children die of the flu. It's a preventable disease … And it doesn't discriminate. It can hit anyone."
After their son's death, the Moises founded Ian's Rainbow Flu Foundation to raise awareness.
Those who have survived influenza say its effects can be devastating.
Luke Duvall, now 20, came down with the flu in October 2009, and it took him a whole year to recover fully.
One-third of his Atkins, Ark., high school was hit hard with that strain of the flu.
Duvall was rushed to the hospital by ambulance. He nearly collapsed in the shower because he couldn't breathe.
"My blood pressure was so low that they couldn't draw blood and I almost crashed in the ambulance on the road," he said. "They had to pull over and stabilize me."
The next morning he was flown to Little Rock, where he stayed for 34 days, much of the time in a coma and on a respirator. "At one time, they had 20 IVs pumping all kinds of things into me," he said.
Duvall spent 17 days in rehab because he had lost 36 of his 157 pounds. "I had to relearn how to walk and how to drink and eat," he said. "I had to relearn daily functions like dressing myself."
All this, according to Duvall, because one student who boarded a football bus for a game had the flu and infected the entire team.
"He was a star athlete," he said. "If he had just had the vaccine, all of this would have stopped. It would have ended there. You don't just get it for yourself, but for those around you. It's a cycle that keeps going."
ABC News information specialist Nicholas Tucker contributed to this report.