FRIDAY, Oct. 26, 2018 (HealthDay News) -- Does getting a flu shot every year diminish its power to protect children?
Absolutely not, say researchers, who found that last year's shot will not in any way reduce the flu-fighting strength of this year's shot.
The conclusion follows three years spent monitoring flu vaccine effectiveness among nearly 3,400 children aged 2 to 17. The researchers said the findings strongly support current recommendations that children get vaccinated against the flu every year.
"Even healthy children can become severely ill and die from the flu," warned study author Huong McLean. She is a research scientist with the Center for Clinical Epidemiology and Population Health at the Marshfield Clinic Research Institute in Wisconsin.
What's more, "the timing and severity of each flu season is unpredictable," said McLean. "The number of children in the U.S. who die from the flu each season varies from about 37 to over 170." In fact, the flu has already claimed the life of one child in Florida this year, she noted.
As to the notion that yearly shots might somehow be overkill, the study clearly demonstrated that "prior vaccination was not associated with reduced vaccine effectiveness," McLean said.
So, she added, "Getting the flu vaccine every year is the single best way to protect against the flu."
The study findings were published online Oct. 26 in JAMA Network Open.
Earlier this fall, data released from the U.S. Centers for Disease Control and Prevention revealed that last year's flu season took the lives of an estimated 80,000 Americans, 183 of them children. Those figures represent the highest flu death toll in 40 years.
The CDC recommends that all Americans aged 6 months and older get a flu vaccine on a yearly basis, with exceptions made only for those who have allergies to one or more ingredients found in the vaccines, or for those with a history of a serious paralyzing illness known as Guillain-Barre syndrome.
As for the shot's overall power to protect, getting a flu shot reduces a child's risk of dying from influenza by more than half (51 percent), according to the CDC. That reflects data covering four flu seasons, stretching from 2010 to 2014.
For the latest investigation, about half the pediatric participants (at an average age of almost 7) were given one of two types of flu shots in 2013: either the live-attenuated influenza vaccine (LAIV), or the inactivated influenza vaccine (IIV).
Ultimately, the team observed that children who had also been vaccinated the year before (2012) ended up with stronger LAIV protection against one type of flu (H3N2) in 2013, compared with those who hadn't been vaccinated in the prior year.
LAIV protection against another flu type (H1N1) was not affected one way or the other by prior vaccination histories, according to the report.
And those children who had gotten a flu shot the prior year (2012) saw no impact whatsoever on the protective strength of their 2013 IIV shot, with respect to both types of flu.
The same flu shot-effectiveness pattern continued to unfold over the next two flu seasons, the investigators found.
While encouraging parents to talk to their pediatrician if they have any questions or concerns, McLean stressed that "the flu vaccine is safe for children and adults."
And because it takes a couple of weeks for protection to take hold after getting a shot, she noted that "parents should have their children vaccinated as soon as possible, so they are protected before the flu season starts."
Dr. Alicia Fry is chief of the CDC's influenza division's epidemiology and prevention branch. She said that the latest study is one of only a few to specifically look at year-after-year flu vaccine power among children.
The findings "are reassuring and support current influenza vaccination policy," Fry said.
"Getting a flu vaccine has been shown to be lifesaving in children. CDC recommends that yearly flu vaccination remains the first and most important step in protecting against flu and its complications," Fry added.
There's more about flu shot recommendations at the U.S. Centers for Disease Control and Prevention.
SOURCES: Huong McLean, Ph.D., M.P.H., research scientist, Center for Clinical Epidemiology and Population Health, Marshfield Clinic Research Institute, Marshfield, Wisc.; Alicia Fry, M.D, MPH, chief, epidemiology and prevention branch, influenza division, U.S. Centers for Disease Control and Prevention, Atlanta; Oct. 26, 2018, JAMA Network Open, online