• Posted June 2, 2026

Childhood Flu Shots Prevent Millions of Cases, Study Finds

Pediatric flu vaccines significantly reduce cases of influenza among children, a new study finds.

For every 100 children vaccinated, as many as 14 fewer children come down with the flu, researchers reported June 1 in JAMA Pediatrics.

"In the United States, that's hundreds of thousands, if not a million cases of flu that we can avoid each year," senior researcher Dr. Anupam Jena said in a news release. He’s a professor of health care policy at Harvard Medical School in Boston.

"That's a huge effect size,” he said.

The results come during an ongoing assault by the Trump administration on the U.S. childhood vaccination schedule.

In January, the U.S. Centers for Disease Control and Prevention (CDC) removed the annual influenza vaccine from its childhood schedule of recommended vaccines, researchers noted.

That change was met with widespread condemnation from medical societies and public health organizations, and it has been blocked for now by a U.S. District Court.

"The federal government cited an absence of evidence that they want to see, and so we have provided that," said lead researcher Dr. Christopher Worsham, an assistant professor of medicine at Massachusetts General Hospital in Boston.

"We have randomized data, and it shows that flu vaccines are effective for these young children,” Worsham said in a news release.

Kids born in the summer typically are less likely to get that year’s flu vaccine, because their annual doctor’s visit around their birthday comes before the vaccine is available, researchers said.

For this study, researchers compared insurance claims data for summer-born and fall-born children between ages 2 and 5. The analysis covered five flu seasons between 2016 and 2023, skipping seasons that were affected by the COVID-19 pandemic.

Children with fall birthdays had vaccination rates roughly 9 to 13 percentage points higher than those with summer birthdays, results showed.

Their rates of flu infection also were found to be lower by 1 to 1.4 percentage points.

"Across these five seasons, we see that for every hundred kids who are randomly vaccinated because of when their birthday falls, somewhere between nine and 14 of them avoid a case of the flu that they otherwise would have caught," Jena said.

But for other illnesses that don’t have vaccines – the common cold or GI viruses, for example – there was no difference in infection rates between the two groups, researchers found.

"It comes down to: vaccines work," Worsham said.

More information

The American Academy of Pediatrics has more on flu vaccine recommendations for children.

SOURCE: Harvard Medical School, news release, June 1, 2026