Vaccinations and issues
This is actually in response to a post by
denyse, wherein she invites discussion of the trend of 'fearing vaccinations' by new mothers. My background is epidemiology, which is the study of disease patterns in populations. I'm not really inviting a flame war or fest or major discussion on the topic, just that my thoughts were too unwieldy for a 'reply' on her journal. If people want to comment, feel free, but I may not further the discussion. ;)
For the purposes of my discussion, when I refer to vaccines, I mean inert vaccines, not live virus ones. That's a whole nother kettle of fish.
From a public health/epidemiologic standpoint:
1) herd immunity is what most people who are gambling by refusing to vaccinate at all are counting on. And it /is/ a gamble. A big one. Why? Because of the growing paranoia/fear of vaccines due to the "autism epidemic".
Herd immunity is the 'relative' immunity that a population that has a majority of its members innoculated provides to unvaccinated individuals. The theory is that there is a person-to-person etiology, and that if most people can't transmit the disease, then my unvaccinated child won't be able to contract it. However, with the incredible fear that exists now in the general population of the vaccines, many parents are choosing not to vaccinate. This means that herd immunity is compromised.
Now, what's the big deal about that, you may say? I mean, come on, how prevalent is polio in today's society?
From 1980 through 1999, there were 152 confirmed cases of paralytic polio cases reported. Of the 152 cases, eight cases were acquired outside the United States and imported. The last imported case caused by wild poliovirus into the United States was reported in 1993. The remaining 144 cases were vaccine-associated paralytic polio (VAPP) caused by live oral polio vaccine (OPV). (source: CDC: http://www.cdc.gov/vaccines/vpd-vac/polio/dis-faqs.htm)
So, not very. HOWEVER: if there is a polio outbreak in the US, there will be a large number of at risk people due to the breakdown in herd immunity. Given the 'global village' that the world has become, this is not as far fetched as it might have been in the 1990s. One only has to look at the beginnings of the Bird Flu zoonotic infections or the recent furor over the individual thought to have drug resistant TB to realize that. Other diseases such as pneumococcal pneumonia, Hep B, rotavirus, influenza, varicella, pertussis, rubella, and Meningococcal pneumonia are moderately to extremely common in the US.
Wait, you say. Hep B? Common in the US? No way!
Actually, yes. An estimated 80-85% of individuals of Asian descent are carriers of hep B. Overall, approximately 1.25 million people in the U.S. are carriers of the hepatitis B virus. (WebMD:http://www.webmd.com/hepatitis/digestive-diseases-hepatitis-b). Also: hepatitis B infection is reported in 2-10% of children adopted from Asia. (Hep B and Adoption from Asia FAQ: http://www.comeunity.com/adoption/health/hepatitis/hepfaq.html). In theory, anyone who has had a service in an asian nail salon is potentially at risk for contracting Hep B. As a parent? I wouldn't want to assume that risk. And hep B is a relatively new vaccine. There is very little herd immunity for it.
Whopping cough (pertussis) has made a huge comeback. Why? Several reasons:
(a) current pediatricians have rarely seen cases and misdiagnose pertussis
(b) rise of anti-biotic resistant 'superbugs' that have allowed the disease to quietly sneak back 'under the radar'
(c) failure of herd immunity because of a rise in parents who have chosen not to vaccinate for DTaP due to fears of a link to autism (DPT: A Shot in the Dark (Coulter & Fisher, 1985))
2) There have been no studies that have found a causal link between vaccines and autism.
Dear god, if it were only that simple. And it's not "mercury in the vaccines" that is the culprit, it's thimerosal.
Thimerosal contains four main ingredients, ethyl mercuric chloride, thiosalicylic acid, sodium hydroxide and ethanol. Ethyl mercuric chloride is essentially an organic mercury. Mercury itself is known to cause neurotoxic reactions in human beings, given high enough doses. While the amount of mercury in thimerosal is very low, infants and young children have much lower levels of acceptable mercury levels for neurological disorders to develop. When vaccines containing thimerosal have been administered in the recommended doses, hypersensitivity has been noted, but no other harmful effects have been reported. Overdoses of thimerosal-containing products have resulted in toxicity. (Vaccinations and Autism: http://www.mercurypoisoningnews.com/vacautism.html)
however, that article goes on to say: The Centers for Disease Control and Prevention (CDC) has found enough data to link mercury-containing vaccines and developmental disorders. Among these disorders are autism, attention deficit disorder, and speech and language deficiencies. It should be noted that the CDC still recommends that parents vaccinate their children. There has however been a strong push by the CDC and other watchdog groups to eliminate thimerosal from all vaccines. (http://www.mercurypoisoningnews.com/vacautism.html)
This is misleading, primarily in the word 'link'. Other data that have been 'linked' to Autism are:
- Gender (male)
- Location (CA, NJ)
- Breech presentation of the baby
- Low Apgar score, an index used to evaluate the condition of a newborn five minutes after birth
- Birth before 35 weeks of pregnancy
- Parental history of schizophrenia-like psychosis
- Parental history of affective disorder, which includes some psychoses, depression, and bipolar disorder
Does this mean that these things cause autism? No. They are CORRELATIONS. The definition of correlation in epidemiology is: the degree to which two or more attributes or measurements on the same group of elements show a tendency to vary together. In other words: take personal histories of the kids who have been diagnosed with autism. See what they have in common. Frankly, because before this study was done in the 1980s, the majority of parents vaccinated their kids, there is an extremely high correlation between vaccines and autism. But that doesn't mean that vaccines cause autism any more than being born with a Y chromosome does.
Also:
Since 2001, with the exception of some influenza (flu) vaccines, thimerosal is not used as a preservative in routinely recommended childhood vaccines. (CDC: http://www.cdc.gov/vaccinesafety/concerns/thimerosal.htm)
Furthermore: the Institute of Medicine reviewed both published and unpulished studies of vaccines and autism and has stated:
the body of epidemiological evidence favors rejection of a causal relationship between the MMR vaccine and autism. The committee also concludes that the body of epidemiological evidence favors rejection of a causal relationship between thimerosal-containing vaccines and autism. The committee further finds that potential biological mechanisms for vaccine-induced autism that have been generated to date are theoretical only. (IOM: http://www.iom.edu/CMS/3793/4705/20155.aspx)
Folks, in epidemiology, you don't state something as a 'cause' lightly. For example, the only absolute casual relationship that is accepted by the epidemiological community as a whole is that tobacco smoke causes lung cancer. And that was only firmly established in the last decade or so.
For people who are on the fence, or who would like to be better educated as regards to vaccines, their roles, and the incidence and prevalences of the diesease they are designed to prevent, I highly suggest further reading at the CDC: http://www.cdc.gov/vaccines/spec-grps/parents.htm, as well as the references I've cited in this discussion. In particular, the role of thimerosal in vaccines and the popular belief that it causes autism, I highly recommend the resources at: http://www.cdc.gov/vaccinesafety/concerns/thimerosal.htm
Vaccination is a choice, primarily because we have a privitized medical and insurance system. Regardless of my personal opinion on the subject, I hope that parents would adequately educate themselves as to the cost/benefit of a particular vaccine and the actual physical data behind it in order to make an informed decision, rather than spend a quick google search, see the words 'linked to autism' and look no further.