I love it when friends read my blog. Maybe it’s simple vanity, but I love being able to talk to people about what I’m writing. Readers who ask good questions (especially friends, because I trust their motives) help me reevaluate my message and my facts.
So an old friend sent me an email this weekend after reading a post, and it’s a question deserving of careful examination. It goes to the mixed messages physicians give to patients even when we don’t mean to.
I was anxious about vaccines and meted them out a little bit more slowly than is typical (only one or two at a time – just took more visits to get them done) but we did them all. Overall, I trust doctors to know a lot more about this stuff than I or any random website I might find telling me not to get them…. however, I always wondered why [pediatricians] advise only introducing one new food at a time, in order to identify the source of any reactions, but give a whole bunch of shots at once. (i’m sure you will have a good explanation for why my analogy is faulty!)
My friend is a mother, writer, and educator. If she doesn’t know the answer, it’s because we as physicians haven’t communicated it well (or because we didn’t anticipate the question!). Sometimes as physicians we err too far on the side of paternalism and expect patients to simply follow our advice without explanation. This is a mistake.
As a parent, the question makes sense to me. There is nothing that concerns me more than my child’s welfare, and seeming inconsistencies in recommendations are going to make me anxious. Often, conflicting health advice is the result of conflicting evidence. I had a patient a couple of years ago who said, “All the doctors are telling me something different. How do I know which one is right?” I told her, “They can fight about it all day, but that’s why we got the biopsy. That will get us the answer.”
The fact that there are uncertainties in medicine does not take away from the validity of medicine. Being able to say, “I don’t know” is essential to any scientific practice.
But what about my friend?
Food allergies are relatively common. The exact reason for this ins’t yet clear, but there are several hypotheses. One is the so-called “hygiene hypothesis” which posits that our hyper-vigilance is hurting our kids. Every time we hold back on exposing our kids to new substances, every time we sterilize a pacifier, we may be preventing important modifications in the immune system—or so it is hypothesized. Really, no one knows yet.
Given the prevalence of food allergies, many pediatricians recommend adding new foods one at a time so that if the child experiences a reaction it might be easier to figure out which food might be responsible. It’s not clear to me that the evidence supports this approach but that’s the way things are currently done.
Vaccines are not associated with significant rates of adverse events. Because reactions are so rare, there is no reason to introduce vaccines in the same way we do with new foods. Also there are a host of positive reasons to introduce vaccinations at certain times, based on risks of exposure and disease, whereas with food, as long as a child is getting sufficient nutrition, no single food is critical.
The science isn’t clear on when and how to introduce foods, but given the frequency of food allergies, caution seems reasonable (unless of course that approach is actually exacerbating the problem, but that doesn’t seem terribly likely). The science is quite clear about the safety and efficacy of vaccines and of the current vaccination schedule, so there is no reason to change the way we vaccinate based on current data.