Ask Dr. Hallberg: Children and immunity

Dr. Jon Hallberg
Dr. Jon Hallberg is assistant professor in family medicine at the University of Minnesota, and medical director at Mill City Clinic. He is a regular medical analyst on MPR's All Things Considered.
Photo courtesy of Dr. Jon Hallberg

During the winter, it can seem like children are always getting sick. MPR's medical analyst Dr. Jon Hallberg said that's because they are building up their immune systems.

Hallberg is a physician in family medicine at the University of Minnesota and medical director of the Mill City Clinic. In a regular feature on MPR's All Things Considered, Hallberg fields questions from parents about their children's medical care.

American Public Media producer Jeff Jones asked Hallberg whether his child is getting sick more often because the toddler has stopped breastfeeding.

An edited transcript of that interview is below.

Dr. Jon Hallberg: It seems by the time that a kid is 6-12 months of age and is no longer breastfeeding that they're getting sick more often. But it's a lot more complicated than just the cessation of breastfeeding.

Tom Crann: What about the issue where it seems like toddlers and small children are getting sick a lot. Are they? And why are they?

Hallberg : They are. It has less to do with not being breast fed, and it has more to do that they're just getting this endless barrage of microbes, and especially viruses.

Crann : And they're new germs to kids?

Hallberg: Absolutely. One after the other. Kids will often find in the winter that it seems they are sick constantly and they kind of are. They might be getting 6-12 infections through the course of the winter.

And the good news is that the body is cataloging all these exposures, so once you get one kind of virus, your body is going to remember that and you won't get sick from that particular one again.

Crann: That would underline that theory you hear, just let your kids get exposed to stuff because they're building up immunity?

Hallberg: That's exactly right. Any kid that's walking this earth is getting constantly exposed to things, no matter how careful we are as parents to not let them get exposed, they are. And, frankly, that's a good thing.

Crann: What's the time period we're talking about here, [their] first couple of years?

Hallberg: The real kind of danger zone is zero to three months because kids are really rapidly building up their immune systems.... They're really going through a lot of illnesses in their first [up to five years] of life.

Crann: What about when we hear warnings. And we do hear warnings for everything from air quality to a new strain of flu and they always say we should really be concerned, especially with small children. Why are they more susceptible?

Hallberg: It comes down to a few different things. On the one hand you've got small tube sizes, so it's an anatomical issue. Their bronchial tubes are very small, so inflammation there proportionally is much more inflammation than we might get. It might make them cough more, wheeze more, have more trouble breathing.

There are things like certain novel strains or new strains of viruses that just seem to be especially hard on kids. And then there's a theory that maybe young kids have such good immune systems that maybe those immune systems are overreacting, they're sending in too many white blood cells, too robust of a response, and that can actually cause some problems too.

Crann: The advice for young parents who are concerned about this is not to wrap your child in a big plastic bubble or anything, right?

Hallberg: No. Toddlers and children need to be kids and be exposed to things and live normal lives. It's a very humbling thing to realize how amazing, and how well the immune system is and works. And it works the vast majority of the time.

If you'd like to submit your question about children and medical care to MPR's All Things Considered, contact @TomCrann on Twitter.

Interview transcribed and edited by MPR reporter Jon Collins.

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