Last Updated on June 1, 2026 by Staff
A new study done by researchers at Harvard Medical School found out that flu vaccines really help keep children from getting the flu. The study was published in JAMA Pediatrics. It showed that for every 100 children who get the flu vaccine we can stop nine to fourteen cases of the flu. This is important because it reminds us that getting vaccines when we are kids is a good idea. There are still a lot of discussions about vaccines. This study gives us new information about how well they work.
The people who did the study think it is a deal. If we can stop a small number of flu cases in a big country like the United States that means we can stop hundreds of thousands or even millions of people from getting the flu every year. The flu is one of the common illnesses that kids get every year and it can make them miss school, go to the doctor and sometimes even go to the hospital.
Birthday Effect
The researchers used a way to study how well the flu vaccine works. They looked at when kids have their birthday. Usually kids get a check-up at the doctor around their birthday. If a kid is born in the fall they can get the flu vaccine at their check-up because it is already available.
Kids who are born in the summer usually have their check-up before the flu vaccine is available. So they need to go to the doctor to get the vaccine and sometimes that does not happen.
This made two groups of kids. One group that got the vaccine and one group that did not. The researchers could compare these two groups to see what happened.
Study Findings
The researchers looked at the health records of kids who were two to five years old over five flu seasons from 2016 to 2023. They did not include the years when there was COVID-19 because that might have changed how people got the flu.
What they found was that kids who were born in the fall got the flu vaccine more often than kids who were born in the summer. Depending on the year more kids who were born in the fall got the vaccine. Between 8.6 and 12.5 percent more.
The kids who got the vaccine got the flu less often. The researchers found that the kids who got the vaccine had about 1.0 to 1.4 percent cases of the flu. This means that for every 100 kids who got the vaccine we can stop nine to fourteen cases of the flu.
The researchers saw this pattern over all five years they studied which makes them more sure about what they found.
Vaccines Work
To make sure that the flu vaccine was really what was making a difference the researchers looked at illnesses that do not have vaccines, like the common cold.
They did not find any difference between kids who were born in the summer and kids who were born in the fall when it came to these illnesses. This means that the flu vaccine is what is really helping to stop the flu.
The study shows that flu vaccines really do work to protect kids from the flu. The researchers think this is important because it gives us the kind of real-world information that people often ask for when they talk about vaccines.
The study also reminds us that vaccines are one of the ways to stop infectious diseases and keep people from getting sick.
Looking Ahead
The researchers said that this way of studying the flu vaccine works best with kids because they usually go to the doctor around their birthday. As kids get older they do not always go to the doctor on their birthday so it is harder to compare the two groups.
This does not mean that the flu vaccine does not work for older kids or adults. It just means that this way of studying the vaccine does not work well for them.
The study also shows us that we can use health databases to learn new things and answer important questions about health. The researchers think that there are more studies like this one that we can do to learn more about how to keep people healthy.
Overall the study tells us a thing: flu vaccines work. They can help keep kids from getting the flu, which can help keep families healthy, reduce the number of people who go to the doctor and stop a lot of cases of the flu every year.