Delaying Vaccines May Increase Seizure Risk
New York Times, By NICHOLAS BAKALAR, May 29, 2014 12:06 pm
Childhood vaccinations like those for measles-mumps-rubella carry a small risk of seizures. Some parents postpone their children’s vaccinations because they believe the delay decreases the risk. But a new study finds the opposite may be true.
The analysis, published online in Pediatrics, involved 5,496 children born from 2004 to 2008 who had seizures in the first two years of life.
For children who received any of their shots as recommended before age 1, there was no difference in the incidence of seizure in the 10 days after vaccination compared with the period before vaccination. But compared with giving it in the first year, giving the measles-mumps-rubella vaccine at 16 months doubled the incidence of seizure, and giving the measles-mumps-rubella-varicella vaccine at that age increased it almost six times.
The risk of seizure after these vaccinations at any age is small — about 1 in 3,000 doses for the M.M.R. and 1 in 1,250 for the M.M.R.V.
“Our study demonstrates a low rate of febrile seizure after the M.M.R. and M.M.R.V. vaccines, and that this rate is increased if the vaccines are received at an older age,” said the lead author, Dr. Simon J. Hambidge, a researcher at the Kaiser Permanente Colorado Institute for Health Research. But, he added, “it is far riskier to delay or avoid vaccination than it is to vaccinate our children.”
This study compares vaccinated children, with a control group of vaccinated children. It's major flaw, is the absence of a control group of unvaccinated children. What is their seizure rate?
It also does nothing to explain why the risk of seizures double when using M.M.R.V as opposed to MMR.
I am not anti-vaccine. I am motivated to ask questions because I have a metabolically vulnerable child. If you are fully confident in the integrity of our vaccine safety information, please ignore this topic, and inject away.