So they explained the controversy, and they had some good takeaways for parents, but all in all, Dateline failed to spend enough time pounding home the multiple studies that have shown no link between vaccines and autism.  Sure, they mentioned the conflicting studies in passing a couple of times, but then they spent an entire segment on an 11-year-old getting a controversial treatment at Dr. Wakefield’s Thoughtful House.  If they truly wanted to have their show be science based, they would have spent a segment on those other studies.

Head on over there and read Rob’s entire review.

Babies Know: A Little Dirt is Good for You

A quick excerpt:

One leading researcher, Dr. Joel V. Weinstock, the director of gastroenterology and hepatology at Tufts Medical Center in Boston, said in an interview that the immune system at birth “is like an unprogrammed computer. It needs instruction.”


He said that public health measures like cleaning up contaminated water and food have saved the lives of countless children, but they “also eliminated exposure to many organisms that are probably good for us.”


“Children raised in an ultraclean environment,” he added, “are not being exposed to organisms that help them develop appropriate immune regulatory circuits.”

So, don’t obsess and over sanitize for your kids. Their bodies need to be exposed to bacteria and germs now and again. And, maybe even the occasional mud pie.

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!