By: Lydia Furman, MD, Assistant Editor
To vaccinate or not to vaccinate- that seems to be the question for a limited number of parents. In a unique approach to this problem, Doctors Carrel and Bitterman (doi: 10.1542/peds.2015-0831) have elegantly analyzed and mapped over time the distribution of California schools in which children have either a “Personal Belief Exemption” or a “Personal Medical Exemption” for vaccination. Certainly the issue is of intrinsic interest, but more pragmatically they ask whether there is enough overlap between high rates of vaccination refusal (“Personal Belief Exemption”) and vaccine ineligibility (“Personal Medical Exemption”) to undermine herd immunity and thus put vulnerable children who cannot be vaccinated at risk for highly communicable vaccine preventable diseases, specifically measles and pertussis.
They classify clusters of schools by tertile, as “high, medium or low PBE (“Personal Belief Exemption”) areas. Certainly some results are predictable and all results are concerning. Higher rates of vaccine refusal, described somewhat euphemistically as “Personal Belief Exemption,” are not surprisingly associated with white students and with charter and private schools. However, not all results are as expected, and the subtleties are worth the read.
Intriguingly the “hotspots” of higher “Personal Belief Exemption” rates co-map with higher rates of “Personal Medical Exemption,” and even more interestingly, the rates of “Personal Medical Exemption” range from 0-19.23% and do not decrease over time. Wait a minute - this sent me back to the books for a refresher on contraindications to vaccination.
The Centers for Disease Control and Prevention treatise “General Recommendations on Immunization: Recommendations of the Advisory Committee on Vaccine Practices” (http://www.cdc.gov/mmwr/preview/mmwrhtml/rr6002a1.htm) clearly spells out the difference between Contraindications (don’t vaccinate) and Precautions (balance risk and benefit). There are very few Contraindications to vaccination: allergy to a vaccine or vaccine component, encephalopathy within 7 days of DTaP that cannot be otherwise explained (for pertussis containing vaccines only), pregnancy or severe immune deficiency (such a symptomatic HIV with less than 15% CD4 cells) for live viral vaccines, and additional contraindications for rotavirus vaccine (severe combined immune deficiency, intussusception)
But these are truly uncommon situations. For example, the rate of anaphylactic reaction to measles containing vaccine appears to be less than 1 case per 1 million doses (http://www.cdc.gov/mmwr/PDF/rr/rr4708.pdf ), and safety data from the European trial of (accellular) DTaP showed no cases of encephalopathy in >25,000 doses (http://www.cdc.gov/mmwr/preview/mmwrhtml/00048610.htm). Certainly some physicians may exercise caution when an infant has a progressive neurologic condition of unknown etiology or a seizure disorder, and hold temporarily on DTaP, but resolution by 1 year of age is usually possible, with subsequent vaccination.
This review led me to the uncomfortable conclusion that many of the “exemptions” described as “Personal Medical Exemptions” may actually be physician-assisted “Personal Belief Exemptions,” i.e. physician-enabled vaccine refusal. It’s really difficult to believe that up to 1 in 5 children could have a medical reason to avoid vaccines. We can strategize about how to best support parents in coming around to vaccination, and can hope that careful, respectful dialogue will pave the way. But in the case of high rates of potentially unwarranted medical exemption, there appears to be a “slippery slope” approach, in which physicians may give parents a medical “out” for vaccination, perhaps hoping parental beliefs will change with time and additional physician input.
Ultimately each of us has to practice in the way we believe is best and answer to ourselves- that is one of the many benefits of our vocation. But I do raise for discussion the question of whether this approach helps anyone, and most of all, whether it benefits the individual child or other children, which is where our responsibility ultimately lies.
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