Seasonal Flu Shots Give Kids Broader Protection Against New Strains

February 7, 2022

A new study finds that kids who have received years of seasonal flu shots have antibodies that provide wider protection against new influenza strains, something researchers say doesn't happen in adults.

These findings could help efforts to develop a universal flu vaccine for children. That would be significant, according to the authors of the study, because kids are at increased risk for serious flu complications such as pneumonia, dehydration and even death.

"Little is known about how seasonal flu vaccination impacts the immune responses in children, who are a major source of flu transmission and a very high-risk group," said lead author Matthew Miller, an associate professor at the Michael G. DeGroote Institute for Infectious Disease Research at McMaster University in Hamilton, Canada.

"Understanding how seasonal vaccination and different vaccine formulations shape childhood immunity is critical for effective prevention," Miller said in a university news release.

The research team spent three years studying immune responses in kids between 6 months and 17 years of age who received either a flu shot or a nasal spray vaccine.

Both types of vaccine worked equally well at generating broadly protective antibodies, the study found. But as kids got older, they were less able to produce broadly protective antibodies, according to the findings.

Children and adults have different immune responses to flu viruses and vaccines, Miller said.

"[When] we give adults vaccines, they make a very specific immune response against seasonal strains," he said. "Adults simply don't generate immune responses to seasonal flu vaccines capable of protecting them from pandemic viruses like children can."

COVID-19 prevention measures such as distancing and masking have resulted in lower rates of seasonal flu, but the flu will return, possibly in dangerous forms, Miller pointed out.

That both nasal and injected vaccines were effective should be welcome news for parents seeking pain-free shots for their children.

"It means we have flexibility in terms of the type of vaccines we can use to make a universal vaccine for children," Miller said. "We now know that children's immune systems are much more flexible than adults' when it comes to being able to teach them how to make these broadly protective responses."

The study was published Feb. 3 in the journal Cell Reports Medicine.

More information

There's more on children and flu vaccines at the American Academy of Pediatrics.

SOURCE: McMaster University, news release, Feb. 3, 2022

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