Hard Conversations: Vaccines and Autism, Part 3
The “Vaccine overload” Hypothesis.
1. The initial “link” between vaccines (MMR) and autism was bad science. It involved small numbers of patients, and could not be replicated. The initial investigator had a large, undisclosed conflict of interest. He is now being investigated for his conduct in this study. Our initial link was weak at best.
2. Thimerosal was never proven to do anything bad, and was removed preemptively. Additionally, there was never thimerosal in MMR vaccine, which is often the one implicated by parents of ASD children.
A commenter on part 1 was trying to assert a third hypothesis. This is one of the McCarthy crew’s new favorites: “Too many, too soon”. Here’s the idea: “Maybe infant’s immune systems can’t handle all those vaccines.”
Before we start, let’s comment on science. Science is restrained. To get scientific evidence, we need questions that are testable. In medical science, we’re further restrained: our testable question also need to be ethical.
Ideas 1 and 2, science had no problems dealing with. This is because they were both theories that easily give testable hypotheses that we could answer by looking at what’s already happened, or through experiments that we don’t think will hurt people.
The first problem is developing a testable question – “too many too soon” is too vague – how many do the anti-vaccers think is too many? How soon is too soon? How are we measuring too many?
Let’s start with how we measure “too many.” Is it by number of antigens, or number of organisms we vaccinate against? Antigens are chunks (protein or polysaccharide) of whatever organism we’re vaccinating against. We form antibodies to these chunks, which are then the basis of our defense against the organism vaccinated against. Essentially an antigen is a practice target.
All that makes “number of antigens” seem like a reasonable way to measure “too many.” Just one problem – in the last 20 years the number of antigens in our total vaccine schedule has decreased, not increased. How can that be? We’ve gotten better at identifying what antigens are important. Once we’ve identified those good targets, we “conjugate” those targets – we make them more visible to the immune system. In 1980, the full vaccine schedule had over 3000 targets. Today’s vaccines only have around 125 targets.
What about how many organisms we vaccinate against? Well I’ll entertain that thought. Just tell me which horrible, preventable disease is the one you’d like to see back. Then tell me how you’ll prove bringing that disease back won’t result in more problems. The anti-vaccine advocates are generally too young to remember how devastating even seemingly innocuous childhood diseases are.
Measles, Mumps, Rubella – they all have “rare” complications that kill, and less rare complications that require hospitalization. But “rare” complications aren’t that rare when the entire country gets a disease. Some of the opposition have said “yes but the mortality rate of [X] disease is only 1 in 1000/10000/otherobscenelylargenumber.”
The problem with that argument is that this isn’t what the mortality would be today. Hospitals aren’t set up for infectious disease anymore. We don’t have isolation wards to stop the spread within the hospital. Heck, at my hospital system (a major metropolitan academic hospital, and major academic pediatric hospital in the Midwest) we’ve rarely had an empty bed, let alone 100 more for an infectious disease ward for sick children. Many hospital systems are at their breaking points as it is, if you add another stress like additional illness that could have been prevented, children will die. I won’t even argue about diphtheria, pertussis, or polio – no one should have to see those diseases, period.
What about “too soon”? We run into problems here as well. Turns out the fetal immune system can respond to antigens at 14 weeks. This is actually surprisingly intuitive, once you consider birth. At birth, a baby moves into the world through the vagina – not exactly a sterile environment. If the infant’s immune system wasn’t pretty healthy from the get go, birth itself would result in a tremendous number of infections. Any OB/GYN worth their salt will tell you that there are a pretty small number of infections that normally happen right around birth; few enough that med students need to know the majority of them for our board exams.
A moment for Jenny McCarthy specifically: in her new book she recommends only taking HIB (haemophilus influenza type B) and tetanus. That’s grossly irresponsible. In a vulgar, arrogant, and ignorant response McCarthy blamed Big Pharma for any deaths that result from her advice. Numerous other bloggers have catalogued the ridiculousness of that position. As we’ve seen, no one has given us something at all convincing to say vaccines are unsafe. Don’t get me wrong, Big Pharma’s not out to help anyone – they’re out to make money, but the burden of proof is on someone to prove their product isn’t safe, and that just hasn’t happened.
With the exception of the paragraph pertaining to the hospital system is based on my own personal experience, the paragraphs discussing ethics, and the paragraph pertaining to Jenny McCarthy, the ideas in this post are based on my interpretation of the below article from the journal “pediatrics.”
Link to part 4 here.
Offit, P., Quarles, J., Gerber, M., Hackett, C., Marcuse, E., Kollman, T., Gellin, B., & Landry, S. (2002). Addressing Parents’ Concerns: Do Multiple Vaccines Overwhelm or Weaken the Infant’s Immune System? PEDIATRICS, 109 (1), 124-129 DOI: 10.1542/peds.109.1.124