While alternative vaccination schedules have become increasingly popular, up until now there has been little data evaluating whether any of the claimed benefits of an alternative schedule are actually real. As many of you know, I’m not the type of doctor to dismiss something out of hand just because it goes against the grain, or because it’s different. I challenge the status quo and embrace the alternative when it’s the right thing to do. But the difference is I would never do or recommend something just because it’s the in thing, I would only recommend it if it were actually better for my patients. And in order to understand this, we need to start collecting information and stop collecting opinions - we need to actually look at kids who delay or skip vaccines and compare them to those that get them on time, and see how they’re doing several years later. At long last, that’s been done. Let’s review what they found.
The long-awaited study was just published this year in Pediatrics from the Division of Pediatric Infectious Diseases at the University of Louisville School of Medicine. The study tracked 1,047 children who received various different vaccine schedules in their infancy. Some had all the vaccines on time, some delayed by various amounts, and some had no vaccines at all. The children were then evaluated at 7-10 years of age to see if there were any differences. The 7-10 year evaluation was very in-depth, with 42 specific neuropsychological tests (!) including assessments of speech and language, verbal memory, achievement, fine motor coordination, visuospatial ability, attention and executive functioning tasks, behavior regulation, tics, and general intellectual functioning. Whew!! In other words, very, very thorough, with a good, long follow-up period.
What did they find? Interestingly enough, those that delayed their vaccines the most did the worst on many of the tests. In fact, those that got all their vaccines on time showed better performance on 12 of the 42 outcomes, and those that skipped or delayed did better on none of them. Now, you would be correct if you said “wait a minute - what about confounding variables?” Fortunately, the researchers thought about that, too. They adjusted for a long list of confounding variables, including education level, income level, breastfeeding rates, maternal IQ...even tuna and nicotine exposure were among many more variables analyzed. And even after adjusting for these variables, those that got their vaccines on time still did better on a couple of the outcomes, and those that delayed their vaccines still didn't do better on any of them. How could it be that the neurodevelopmental outcomes might be better in those that receive all the vaccines on time? Easy! Don’t forget that most of the infant vaccinations specifically protect babies against things that cause brain damage: pertussis, meningitis, sepsis, encephalitis, etc...
In summary, there are few important points to take home here:
Delaying or skipping vaccines does not improve neurologic, psychologic, behavioral or developmental outcomes, as the proponents of alternate schedules claim, but it does increase risks.
All the people in this study live within a population that has herd immunity. This means the people without timely vaccination are still benefitting from the herd immunity gained from those with timely vaccination. Even with this being the case, they still do worse by delaying vaccines, albeit subtly so. Imagine if you took this benefit away? If you compared entire populations with and without timely vaccination, you would see a much more massive benefit to timely vaccination, and massive risk to delaying or skipping vaccines - the true risk. This study merely proves there is no benefit to delaying; that doing all of the vaccines on time does not cause any neurologic, psychologic, behavioral or developmental problems when compared to spreading them out or skipping them.
On a side note, it was interesting from a social perspective that those who delayed vaccines tended to have lower education and income levels. It's frustrating to the community advocate in me that those with less education or money should receive less accurate information, and ultimately receive worse health care. I am passionate about providing equal time, equal healthcare and equal information to all families, and hope to bridge that gap! I think part of this is about trust as well; those less fortunate may have been hurt by the medical system and are less likely to trust their doctors. I hope to bring trust back into the relationship as well, and want all my patients to know that my care comes from a place of love, compassion, and equality.
Citation: “On-time Vaccine Receipt in the First Year Does Not Adversely Affect Neuropsychological Outcomes.” Michael J. Smith, MD, MSCE and Charles R. Woods, MD, MS.