the vaccine war



Sigall Bell, M.D.
April 26, 2010 11:33
Sigall Bell M.D.An assistant professor of medicine at Harvard Medical School and a member of the Division of Infectious Diseases, Beth Israel Deaconess Medical Center. She is the director of the BIDMC travel medicine clinic and the mother of two young children.

A few months ago I got an email from my cousin. "Should I really be giving my baby all these vaccines at once?" Spacing vaccines is now a hot topic among young mothers. Why do them all at once when you can spread them out over several visits?

Curious, I raised the question with my own pediatrician. "I can do that if you want, "she said, "but I feel bad for my relationship with the child." How can they grow to trust their doctor if every visit comes with a needle? And they learn fast. With just a handful of words under her belt, my daughter mustered up "Oh-oh!" as soon as we checked in for her 12 month visit.

So then I researched the issue and discovered something surprising: Despite routinely vaccinating our infants and toddlers against 14 pediatric diseases [PDF] (15 if you count H1N1), compared to the single smallpox vaccine kids got a century ago, their immune systems get less of a workout. How can that be?
Vaccine biology is much improved today. With purified proteins and recombinant DNA technology, we can target the desired antigen -- that component that we want the immune system to "see" and remember -- much more specifically. So while vaccines of the past may have had hundreds of antigens, today's vaccines can have as few as one. Here's the take-home: kids today get many more vaccines than the children who got the solitary smallpox vaccine, but they actually receive less immunologic triggers (approximately 150 versus 200 antigens from smallpox, according to researchers).

Here are some more interesting numbers: using conservative estimates of immune system capacity, scientists estimate that infants could theoretically respond to about 10,000 vaccines at any one time. No one's going to do that, but it does put things in perspective. For those who worry that multiple vaccines "overwhelm" the immune system, these researchers suggest that even 11 vaccines given at once only occupies about 0.1 percent of the immune system's attention.

I fully confess that I'm the parent who has to leave the room when our kids get vaccinated (my husband is the official "holder"). Spacing sounds very rational. But there are a few poorly publicized arguments against it that are worth considering when you make your decision. Even beyond the pediatrician relationship issue, and the overall lower antigen load, I just can't bear the thought of putting them through more total vaccine visits than we need to. For others, the scales may tip in the other direction. At this point, I think the spacing decision is best made by weighing your own pros and cons. Talk it over with your pediatrician. My personal feeling is get it over with, until there is more compelling evidence that spacing works. That's what I told my cousin. What would you say?

posted april 27, 2010

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