Ok, I’m almost done with HepB, I swear. Just a couple of things that have been bouncing around since I posted the first bit, but haven’t had a chance to cover.
When you google for info on the HepB vaccine, or any vaccine, and include any vaguely negative modifiers (e.g., negative effects, risks, delay, and any disorders under the sun), you end up with gads of hits like mercola.com, or nvic.com, that have a lot of articles that are kind of terrifying. Mercola is outrageously sensational, to the point of being ridiculous, to me at least. NVIC concerns me more, because it has a more even tone – so the misinformation is even more insidious. A couple of the ideas these websites purport in relationship to the HepB vaccine are that it is linked to autism, sudden infant death syndrome (SIDS), and autoimmune disorders.
Autism: the headlines read “Hepatitis B Vaccine triples the risk of autism to infant boys,” in no uncertain terms, and the articles have no discussion of the limitations of the study it’s based on. I read the study, because I’m charitable like that, and here is some additional information. First off, the major findings of the study: the rate of autism in a group of boys who received the HepB vaccine win the first month of life was three times higher than the rate of autism in a group of boys who did not receive the vaccine in the first month of life. Sounds scary, right? Well what isn’t made clear is that the sample sizes are small. The total number of autistic boys considered for that claim was 30. That’s … not very many. The study was a case-control study, which is a particular kind of epidemiological study ideal for identifying associations between disease and exposure; they cannot identifying causality. Additionally, they are ideal for diseases that are very rare. Autism is not particularly rare, at this point, and 30 boys is rather a paltry sample size for such sweeping statements of risk. Additionally, while working on this study, the authors noted that HepB vaccination seemed to exert a protective effective on infant girls, but the sample size is small, so… *shrug*. I draw attention to that only to underscore the absurdity of their headline grabbing claims.
SIDS – I actually can’t find any scientific studies claiming a link between HepB vaccines and SIDS. On mercola.com, this is chalked up to under reporting, and government conspiracy. I can’t argue with crazy, so … I’m sorry if you think there is a government conspiracy. *Head pat* here are some publications talking about how there is no association.
Autoimmune disorders – such as lupus, multiple sclerosis, etc. Now this is actually interesting. Autoimmune disorders occur when the immune system freaks out and starts attacking the body it’s supposed to be defending, in various ways. Scientists don’t fully understand how the immune system ends up getting confused, but there are a couple of popular theories. One theory is based on the fact that some autoimmune disorders are strongly correlated with exposure to a particular antigen, such as with Guillan-Barré and Campylobacter jejuni. This mechanism makes sense – dysfunction of the immune system in autoimmunity is basically an exaggerated, inappropriate response to an antigen, or misdirected response at some autoantigen (some normal part of the body, like peripheral neurons). Molecular mimicry can be the issue here – the autoantigen looks like an actual antigen, and the immune system gets hoodwinked, and over reacts like a crazed toddler. Another theory holds that some host tissue insult causes the body’s immune cells to incorrectly imprint on autoantigens released due to an injury.
So, it kind of makes sense that you could see an increase in autoimmune issues after vaccination – vaccines can cause inflammation, they are designed to elicit an immune response. In some small segment of the population, that response could be overblown or misdirected. Ok so is this correlation actually happening? Well, no, it does not seem to be. There have been some reports of relapse and aggravation in adults subsequent to HepB vaccines, but controlled epidemiological studies have not been able to establish any formal associations (reviewed in Millet et al., 2009).
In summation: HepB vaccines for everyone! Down with hepatitis!