Fact or Fiction? “Building” Your Child’s Immunity Through Illness
When my daughter caught her first cold in the daycare at the YMCA, people told me that it was, in the long run, a good thing. Getting sick now, they said, would build her immune system and make her stronger. If it didn’t happen in daycare, then it’d happen in preschool. No matter how much I wanted to protect her, she would eventually have to go through a period of illness. Getting sick was a right of passage into the world of immunity. Was this an old wives’ tale, I wondered, or was there any truth to it?
In order to answer this question, I did some research on how the immune system works, and this is what I found. The immune system is divided into two main functions: innate and adaptive immunity. Innate immunity includes the white blood cells designed to attack all foreign pathogens. Adaptive immunity uses the white blood system to remember the pathogens the body has encountered and use that memory to create antibodies that fight the pathogen more effectively the next time it is encountered. Adaptive immunological memory is the principal behind vaccinations.
Babies are born without any immunological memory, though some antibodies do cross the mother’s placenta and help protect the child. Breastfeeding helps solidify this protection by passing the mother’s white blood cells – and their specific, adaptive immunity – to the child. Through breast milk, babies can gain some protection from the mother’s experience with a variety of pathogens. There is an excellent review of the medical literature here.
Children do have to be exposed to viruses and bacteria in order to develop specific immunity. In this way, sicknesses do help build a child’s immunity. But let’s think about the pathogens that a child is likely to encounter.
First and foremost, there are those diseases for which we have developed vaccines. These are some of the most dangerous viruses and bacteria on the planet. With vaccines, we can bypass the illness and move directly into learned immunological response by building antibodies to dead or attenuated pathogens. Then there are specific childhood diseases, to which kids can become immune to through illness. Chicken pox is one example. The pathogens that cause these illnesses are relatively stable, unlike the viruses that produce the common cold. The constellation of common cold viruses is incredibly diverse, which is why a vaccine for this illness does not exist. In addition, the cold virus mutates quickly, making it nearly impossible to develop a specific, adaptive response to it. Mutations are also common to the virus that causes influenza, though a vaccination is possible. But that vaccination has to be given each year, because the rapid mutations make the previous year’s vaccine null and void by the next flu season. The CDC attempts to predict which mutations will occur, but they are not always right, as anyone who has gotten both the flu vaccine and the flu can attest.
Most of us have had a cold before, and most of us will get another one again. While our bodies have learned to respond to one virus mutation, it has to learn again as soon as another mutation comes along. In other words, even if your infant beats the cold she picked up in daycare, she will not be immune from the common cold. She will have to beat it again and again. Illness, in this case, does build her immunological memory, but it won’t prevent her from getting the sniffles.
There is, however, some possibility of cross-reactivity in your child’s immunological response. While cold viruses mutate, the viruses do share common attributes. As such, the immunological system can learn to recognize the common factors and respond appropriately. In terms of experience, this means that the first time your child gets a cold, it will generally be more severe and last longer than the second, third, or fourth time. Your child’s system will be better equipped to respond to a virus it partly recognizes.
The answer, then, is that illness does build your child’s immune system. Exposing your child to chicken pox will help protect her from later bouts with this particular illness. But getting a cold in daycare probably won’t prevent your child from getting another cold in preschool or kindergarten. And your own experience with the common cold isn’t likely to prevent you from catching whatever she brings home from daycare, either!
Mark M Said,
November 22, 2008 @ 5:07 pm
While the immunological benefit of exposing your kids early to colds and the like may not be pronounced, it always struck me as somewhat unfortunate for the children whose parents limit their social contact to other kids in order to prevent illness. Living in a condo, the social benefit and education my kids get from frequent trips to the playground and playroom in my opinion far outweigh the cost to them and me of the occasional sniffles and doctor’s visits. Heck, I’ll a few long nights for kids that play well with others any day.
But don’t take my word for it – to quote Ms. Frizzle – “Take chances. Make mistakes. Get messy.” and have a good medical book on hand so you know when it is time for a trip to the doctor’s.
Kate Said,
November 22, 2008 @ 5:07 pm
There was an excellent study done at the Australian National University about 10 years ago examining exactly that, do kids who get sick more often get as sick once they start primary school. The study (from memory!) said that if kids are sicker from daycare germs then they get less sick once they go to school. I don’t have the reference, sorry, but you should be able to look it up if you are interested
chanson Said,
November 23, 2008 @ 12:11 am
People also claim that the reason allergies are on the rise in industrialized nations is because our environment is relatively sterile. Do you know if there’s any evidence to back that claim, or if it’s just a question of making guesses based on correlations?
Julie Said,
November 23, 2008 @ 2:45 pm
Thanks for writing about this so well, Jennie! I admit that I am the one who parroted the old claim about colds building immunity. I heard it from my husband, who heard it from his sister…. I was trying to reassure Jennie after that YMCA incident.
So I’m glad to know the degree of truth involved in this claim. So much of the time we hear these claims and accept them, but we don’t know the science behind them. This post is to me the essence of why Jessie and I started this blog, so kudos!
Meanwhile, we are dealing with an attack of croup over hear at my place. I’m afraid this is also a daycare related event. I may do a post about croup, just for the heck of it.
Dr. Chuck Said,
November 23, 2008 @ 5:30 pm
I’m not sure if physician input is encouraged in this blog, but I wanted to complement you on a well written entry. I, too, have seen the study mentioned by Kate, above, citing a decrease in absenteeism in early elementary school among those who attended daycare. I often mention the study to parents who are guilt-ridden about their child’s frequent daycare-related illnesses. The problem is that older children often handle colds better and are less likely to develop ear infections. Daycare is often a necessity for parents, however, and the benefits to the family of having two working parents must be weighed against the risks of more frequent colds.
The theory Chanson mentioned is called the “Hygiene Hypothesis” and has some support in the literature. It is controversial, however. Even if true, one has to decide whether allergies and asthma or frequent viral and bacterial infections are the lesser of two evils. I would never recommend intentionally exposing your children to a “wild” illness (as opposed to a “weakened ” virus in a live vaccine) with the goal of stimulating their immune system. The second child in a household exposed to chicken pox, for instance, often develops more severe disease and is at increased risk of complications such as cellulitis and pneumonia.
Julie Said,
November 23, 2008 @ 8:13 pm
Dr. Chuck, thanks for reading and commenting! Your input is encouraged. I hope you continue to visit us.
Philb Said,
December 1, 2008 @ 3:22 pm
Wow, I’ve held the “Hygiene Hypothesis” for years but didn’t realize it’d been suggested or studied at all seriously.
For myself I grew up on a farm walking around and in sheep pens, bales of hay, and the like, and I’ve never experienced anything like the allergy symptoms that friends report.
My own personal take on stuff of this sort is more along the lines of the parent(s) being able to relax a little. I agree with Dr. Chuck that deliberately exposing kids to an illness just doesn’t sound right. On the other hand, fear of a kid getting germs shouldn’t prevent them going to the playground and park either.
Nancy Said,
December 12, 2008 @ 7:46 pm
Just an added point on breast feeding. The immunity it offers is localized. That is, mainly for gastro-intestinal things. It’s not going to help with colds though there’s some evidence to show that bf babies have fewer ear infections.
Me Said,
January 22, 2009 @ 1:33 pm
very interesting, i always wondered about that.
Nikki Said,
January 27, 2009 @ 9:50 pm
it has been so helpful to read this blog. I have a 4 month old who was just hospitalized over Christmas with RSV that turned to Pnemonia. I have been Soo guilt-ridden b/c she attends daycare and I feel like I caused this!! This is my first, so I’ve been your typical new mommy, but it seems like she just keeps catching another virus. I can’t keep her 100% for very long!
I really would love to believe it will all stop and she’ll “build her immunity”.
Jennie M Said,
January 29, 2009 @ 1:31 pm
I certainly did not want to suggest that we should closet our children or make anyone feel bad about going to daycare. Kids get colds. It’s a part of life! They can get colds if they go to daycare or even if stay home most of the time — in our house right now, we all have a pretty nasty rhinovirus right now that we caught from the nanny who comes only twice a week. There are certain things we can do to try and prevent the spread of infection, but we’re humans and we touch each other, spreading both infection — and love.
JoDee Said,
February 27, 2009 @ 5:38 pm
My site is not up and running yet but will be in a week or so. I found this blog very intriguing and do agree with it. However, I do have a little bit of a different view or ways to help our children, I guess.
My first child was sick almost since birth with one thing or another. The pediatrician kept putting her on antibiotic one after another. She would just get off one, a week later get a runny nose then turn into something more severe. Finally, when she was three years old, I just couldn’t stand it anymore. The doctor bills were just crazy and I finally realized, her immunity was so low, that no matter what she caught, it always went into something more severe. I finally decided to take matters into my own hands.
I started researching vitamins and building your immunity through vitamins. To make along story short, I started her on vitamins and my daughter does not go to the doctor anymore except for vaccines and annual visits! My second daughter has been very healthy since birth and I definately believe it is due to the vitamins they take daily. If you are interested, I also blog this on
http://buildinghealthykids.blogspot.com/.