There antivaccination crowd runs the gamut from truly scary deniers who invent all sorts of lies to try to stop vaccines to people who seem to think that the risk of vaccine adverse events somehow surpasses the risk of the disease itself, mostly because they lack the cultural memory of what it was like in the world pre-vaccines. Vaccines are a critical part of the drop in the infant mortality rate by over 90% since the 1930’s, so we have just forgotten.
There is a group of parents that kind of sit in the middle of the so-called “vaccine debate.” They are not necessarily opposed to vaccinations, but they pick and choose which vaccines they give their children, and they have come up with a revised vaccine schedule which has no basis in science. Dr. Sears (there’s four of them in the family, and they all say the same thing) is one of the more notable proponents of the revised vaccination schedule. In general, the vaccine delayers avoid some vaccines (Hepatitis-B being the most important one), and delay or even eliminate boosters shots.
The current US-based vaccine schedule is established by some pretty bright people. The Advisory Committee of Immunization Practices, a part of the US Centers for Disease Control and Prevention, the world’s leading center for detecting and preventing infectious diseases, is made up of some of the nation’s leading experts on infectious disease, immunology, vaccines, and public health. Their only goal is to determine which vaccines are necessary to protect the lives of citizens of the USA, and then to establish a healthy schedule for those vaccines. They do not pull this data out of thin air, but is based on the best research evidence available to them. As I’ve written before, vaccines prevent over 42,000 deaths every single year.
A recent study found that delaying the MMR vaccine (for measles, mumps and rubella), in the second year of life, doubled the risk of a seizure occurring after the vaccination. Now seizures are not unusual with vaccination, and are a result of the high fever that some children get after vaccination. But seizures are fairly common in children who haven’t been vaccinated recently. It’s always scary to parents, but they are minor, usually cause no long-term damage, including epilepsy.
The researchers, led by Simon Hambidge, MD PhD, of the Institute for Health Research at Kaiser Permanente Colorado, analyzed data from 323,247 children, born between 2004 and 2008, whose records are in the Vaccine Safety Datalink system, a collaborative effort between CDC’s Immunization Safety Office and 9 managed care organizations (MCOs), that monitors immunization safety and address the gaps in scientific knowledge about rare and serious events following immunization
The researchers located records 5,667 children who had experienced a seizure in their first two years of life and did not have a seizure disorder. The researchers then compared the timing of these children’s seizures to the dates they had received various vaccinations and considered whether the vaccines had been received on time or not, per the CDC’s and ACIP’s recommendations
The analysis revealed that there was no correlation between receiving any vaccine and experiencing seizures for children during their first year of life. However, those children who received the MMR vaccine between 12 and 15 months old, when it’s recommended, were at about 2.6X higher risk of a seizure than an unvaccinated child. That translates to about one seizure for every 4000 children receiving the vaccine. If parents delayed the MMR vaccine until any time between 16 and 23 months, the risk of a seizure was 6.5X greater than when not being vaccinated. In other words, delaying the vaccine 4-8 months more than doubles the risk of seizures.
In general, febrile or acute seizures are not serious, they just seem scary. Most vaccines, such as DTaP (the vaccine for diphtheria, tetanus and whooping cough) actually show no difference in seizures between vaccinated and unvaccinated children. Seizures occur in about 5 out of 100 children sometime during their lives, with 95% of them not serious or symptomatic of other diseases. In other words, the background risk of seizure might actually be higher than the incidence observed in vaccinated children, just in case a reader wants to head down that path.
Thus, if you’re coming up with your own vaccine schedule, you’re increasing the risk of a minor, but kind of scary, adverse event–a febrile seizure. Why would one do that to gain no other benefit? That’s not clear to me.
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Key citations:
- Daley MF, Yih WK, Glanz JM, Hambidge SJ, Narwaney KJ, Yin R, Li L, Nelson JC, Nordin JD, Klein NP, Jacobsen SJ, Weintraub E. Safety of diphtheria, tetanus, acellular pertussis and inactivated poliovirus (DTaP-IPV) vaccine. Vaccine. 2014 May 23;32(25):3019-24. doi: 10.1016/j.vaccine.2014.03.063. Epub 2014 Mar 31. PubMed PMID: 24699471.
- Hambidge SJ, Newcomer SR, Narwaney KJ, Glanz JM, Daley MF, Xu S, Shoup JA, Rowhani-Rahbar A, Klein NP, Lee GM, Nelson JC, Lugg M, Naleway AL, Nordin JD, Weintraub E, DeStefano F. Timely Versus Delayed Early Childhood Vaccination and Seizures.Pediatrics. 2014 May 19. pii: peds.2013-3429. [Epub ahead of print] PubMed PMID: 24843064.
