(CNN)When adults want a flu shot, they have two choices: go to the doctor or go to a pharmacy.
But in most states, laws prevent parents from just walking into a pharmacy and getting their children vaccinated for the flu. Public health experts say that's costing children's lives.
"Parents should have no barriers whatsoever to getting a flu shot," said Dr. Irwin Redlener, director of the National Center for Disaster Preparedness at Columbia University. "It's what we'd call a no-brainer."
Currently, 40% of children don't get a flu vaccine, and public health authorities are keen to change that. Flu kills children every year; last year, 143 children lost their lives to the flu.
Another reason to get children vaccinated: With their less than ideal hygiene, they're powerful at spreading the flu to others.
Pharmacies are an attractive alternative for many busy parents, since they have evening and weekend hours, and there's no need for an appointment.
But three states -- Florida, Connecticut and Vermont -- don't allow children to be vaccinated in pharmacies, and another 30 states have restrictions based on the child's age.
"We're relinquishing our responsibilities as a society if we don't really aggressively try to get as many children vaccinated with the flu vaccine as possible," added Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases. "I just want to see more children get vaccinated. I don't really care how you do it."
It's unclear why so many states restrict children from getting the flu vaccine at pharmacies. The American Academy of Pediatrics doesn't object to children getting vaccinated at pharmacies, according to the group's position paper on preventing flu.
"It's the same vaccine. Pharmacists are trained to give it. I had my own flu shot at a pharmacy and my grandchildren have, too," said Redlener, who lives in New York, where children over age 2 can get a flu vaccine at a pharmacy.
Fighting with the pediatrician's office
All Kristin Nabers wanted to do was get her children a flu shot -- and she had to argue with her pediatrician's office.
Her pediatrician's office is a 30-minute drive away, and then there's time in the waiting room. That means Nabers or her husband would have to miss half a day of work, and her children, ages 4 and 6, would have to miss school.
The pharmacy, on the other hand, is a mile away from her house, and it's open evenings and weekends.
Nabers chose the pharmacy. She lives in Georgia, where children under age 13 need a prescription to get a flu shot at a pharmacy.
She contacted her pediatrician's office. The nurse refused.
"The nurse told me for reasons of 'continuity of care' they couldn't call in a prescription," Nabers remembers. "I was like, really -- for a flu shot?"
Nabers asked the nurse to reconsider.
This time, she received a different answer. She was told that if children get their flu shots in pharmacies, the pediatrician's office wouldn't know how many to order for the following year.
Nabers understood the bureaucratic predicament, but it still didn't seem like a good enough reason for her or her husband to miss work, or for her children to miss school. She even considered finding a new pediatrician.
"I didn't threaten to leave, but I told them while I loved their practice, I was very unhappy with this and would have to consider it moving forward," she said.
Only then did the office call in a prescription to the pharmacy -- and the nurse made it clear that it was a one-time exception.
"We went in, filled out the forms, and bam, we were in and out in 20 minutes, with shots for me and my kids," she said.
Nabers thought about parents who don't have the time or the will to argue with a doctor's office the way she did. She thought about parents who, unlike her or her husband, don't get paid if they miss work because a pediatrician refuses to call in a prescription for a flu shot -- a shot the US Centers for Disease Control and Prevention, the American Academy of Pediatrics, the World Health Organization, the Infectious Disease Society of America, and countless other groups recommend.
"We're told we need this for our children's health, and I am bought in. I am fully bought in," she said. "What I'm not bought into is this barrier to health. This should be easy."
Sen. Ben Watson, chairman of the Senate Health and Human Services Committee in the Georgia Legislature, said he's open to re-examining the law.
"I think more people should be vaccinated, and we should make it easy for them to be vaccinated," said Watson, who is a physician. "I certainly would be willing to re-visit this issue."
He added that the issue has not been front and center.
"The CDC and the [National Institutes of Health] haven't pushed this issue, and it hasn't risen to our attention," he said. "If it's not a squeaky wheel, I hate to say it, then it doesn't get addressed."
Fauci, the infectious disease expert at the NIH, agreed.
"I think when you keep bringing attention to it, somebody's going to wake up and say, 'OK, here's what we need to do,' " he said.
'Moving in the right direction'
Jennifer Miller remembers the fall of 2012 as a particularly busy time for her family, who live in Westfield, New Jersey.
Five-year-old Caroline had just started kindergarten, and she was selling hot cocoa at community events to raise money for the victims of Hurricane Sandy. Her sister Katie was in third grade and on the swim team.
Miller meant to call the pediatrician's office and make an appointment for her daughters to get flu shots, but each day got busier and busier. Going to their local pharmacy wasn't a choice because at the time, New Jersey didn't permit children of any age to be vaccinated in pharmacies.
"September became October, and October became December. I remember us getting closer to the girls' holiday vacation, and I thought, I'll go ahead and get them vaccinated then," Miller remembers.
She never got that chance. Ten days before Christmas, Caroline, their 5-year-old, woke up with the sniffles and a cough. By that evening, her breathing had become labored. Her parents brought Caroline to a local hospital where she was put on a ventilator and airlifted to Children's Hospital of Philadelphia.
"I never expected that the child who a day ago was doing somersaults in the front hallway was now going to be intubated," Miller said. "She literally had no lung function at all."
Miller still feels guilty that she didn't get her daughter a flu shot. But she says New Jersey could have made it a whole lot easier.
"You're passing by these pharmacies on a regular basis. You're already there. It's one quick step and you could go in anytime," she said. "That fall, I absolutely would've taken advantage of having her go to a pharmacy to get vaccinated."
She said other families she knows who don't get the flu shot aren't avoiding it -- they're just busy.
"It's not so much, 'Oh I don't want to get it done.' It's 'Oh my gosh, add it to the list of a million things I already have to do. Can someone please make this easier for me?' " she said.
Some states have made it at least somewhat easier. In 2014, the New Jersey legislature legislature voted to allow pharmacists to give the flu vaccine to children age 7 and older.
But Serese Marotta, chief operating officer of Families Fighting Flu, says it's just common sense that states should allow children of all ages to get vaccinated in pharmacies.
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She's seen success in her home state of New York, which up until recently didn't permit anyone under the age of 18 to get a flu shot in a pharmacy. Then in January 2018, during a particularly severe flu season, Gov. Andrew Cuomo issued an executive order allowing children age 2 and older to get the flu vaccine in pharmacies.
In the four months following Cuomo's order, about 9,000 flu vaccines were given to children in pharmacies, according to Jonah Bruno, a spokesman for the state Department of Health.
"Common sense tells us that if we make it easier for people to go get a vaccine, then at the end of the day we're moving in the right direction," Marotta said.