Wednesday, September 14, 2011

Vaccinations (incl. MMR)


I'm not sure if anyone else has noticed this, but it appears that vaccinations have been brought up in the media lately.  I will lead this post with a disclaimer that I know comparatively little about vaccinations (my education has focused on physical science), but I feel that I know enough to write an informed post on the subject.  Prepare yourself for the starry-eyed wonder of a non-life-science type marveling at the human immune system.

I will start off by explaining the routine influenza vaccination, because I assume most vaccinations work on the same principle.  The vaccination itself consists of virus strains which have somehow been stripped of their ability to harm humans (preventing reproduction or harmful traits).  The strains represent different mutations of the influenza virus, the mutations representing different evolutionary strategies of the global influenza population.  Now, these two facts are important because they represent the rationale for most complaints I hear about the vaccine routinely given during flu season.

The most prominent (and baffling, in my opinion), is that "the flu vaccine gives me the flu."  No.  No it does not.  When the human body detects the presence of the influenza virus, it [sometimes] responds by the same mechanism it would in the event of a full infection.  That is to say, fever, aches, runny nose, et cetera.  The body then forms the necessary antibodies to prevent another infection from that specific strain of influenza (this will be important later).  However, rather than flu-like symptoms on week timescales, you might experience it for a day or two.

Another complaint I hear about the flu vaccine is "I got the flu shot, but I still got the flu!  Also, I hate monocles and top hats!"  Now, while the latter half of this statement is no doubt infuriating, take it as an indicator of the quality of person giving the statements.  This problem can represent that the flu shot only protects against ~90% of the influenza strains in the wild, however, it is often due to misattribution of sickness.  The most likely explanation for this is that people get sick with infections not due to influenza, but attribute it to the broadly misused term "flu" (as in "I have a stomach flu" meaning "I have diarrhea", or "I have a 24 hour flu" meaning "I have a short-lived bacterial infection").

Now, to the point of this post.  The MMR vaccine is a shorthand reference for Measles-Mumps-Rubella vaccination which is commonly administered to small children.  A publication in a medical journal The Lancet in 1998 suggested that the MMR vaccine could cause autism in susceptible children.  A dozen papers to the contrary and twelve years later, The Lancet retracted the incorrect article, but the damage was done.  Misinformed (and potentially over-protective) parents everywhere attempt to refuse the vaccination for their children.  This is due largely to parents reading internet articles without thinking critically (but you can totally trust my blog posts, guys!), and the ready acceptance of anecdotal evidence (e.g. But Shirley has a cousin who's uncle's kids got autism from MMR!)

I have also heard the concept of the "free rider" or "herd immunity" hypothesis used in defense of going without the MMR vaccine.  The theory here goes that if a large enough percentage of a population is vaccinated against MMR, those un-vaccinated children are unlikely to contract the disease.  Naturally, this argument breaks down when one considers globalisation, and that these children are the only vulnerable ones in the larger population, and will probably get sick.

My room mate (with a B.Sc. in Health Science), also raises the argument that in the best interest of publicly funded health care, Canada and/or Public Health would not release a vaccination with any known risks or correlations (or at least not without signing a long and wordy contract identifying all risks of the vaccine).  It's a valid argument, especially considering that the Canadian health care system would then be forced to deal with higher health care costs associated with autistic children.

I admit that children go without getting vaccinated because their parents are trying to protect them.  I do not have children, and have not experienced the profound shift in thinking that parents undergo, but I still do not understand the opposing viewpoints on vaccinations.  All I can do is recommend critical thinking when you read.  It's a profoundly rewarding endeavor.

Note: For the record, the leading graph is the reason that children receive the MMR vaccine.