“The science is largely complete. Ten epidemiological studies have
shown MMR vaccine doesn’t cause autism; six have shown thimerosal
doesn’t cause autism.”
-- Dr. Paul Offit, “Autism’s False Prophets”
“16 studies have shown no causal association between vaccines and
autism, and these studies carry weight in the scientific industry.”
-- Dr. Nancy Snyderman, NBC Today Show Medical Editor
Conventional wisdom holds that the autism-vaccine question has been “asked and answered,” and that least 16 large, well-constructed epidemiological studies have thoroughly addressed and debunked any hypothesis that childhood vaccination is in any way associated with an increased risk for autism spectrum disorders.
But there are several critical flaws in such an oversimplified generalization, and they are rarely given close examination by public health experts or members of the media.
To begin with, it is unscientific and perilously misleading for anyone to assert that “vaccines and autism” have been studied and that no link has been found. That’s because the 16 or so studies constantly cited by critics of the hypothesis have examined just one vaccine and one vaccine ingredient.
The current US childhood immunization schedule calls for 28 injections with 11 different vaccines against 15 different diseases by two years of age. Of those 11 vaccines, only the Measles-Mumps-Rubella (MMR) shot has been studied in association with autism, (although a CDC study of an MMR-plus-chickenpox vaccine did show that the risk for febrile seizures in infants was doubled.)
Meanwhile, those 11 vaccines contain scores of ingredients, only one of which, thimerosal, has ever been tested in association with autism.
It is illogical to exonerate all vaccines, all vaccine ingredients, and the total US vaccine program as a whole, based solely on a handful of epidemiological studies of just one vaccine and one vaccine ingredient. It is akin to claiming that every form of animal protein is beneficial to people, when all you have studied is fish.
Now, a new study has shown that giving Hepatitis B vaccine to newborn baby boys more than triples the associated risk of developing an autism spectrum disorder.
An abstract of the study was published in the September, 2009 issue of the respected journal Annals of Epidemiology. In it, Carolyn Gallagher and Melody Goodman of the Graduate Program in Public Health at Stony Brook University Medical Center, NY, wrote that, “Boys who received the hepatitis B vaccine during the first month of life had 2.94 greater odds for ASD compared to later- or unvaccinated boys. Non-Hispanic white boys were 61% less likely to have ASD.” The authors used U.S. probability samples obtained from National Health Interview Survey (NHIS) 1997–2002 datasets.
The conclusion states that: “Findings suggest that U.S. male neonates vaccinated with hepatitis B vaccine had a 3-fold greater risk of ASD; risk was greatest for non-white boys.”
The author’s new study used a different database than their earlier
study (NHIS vs. NHANES) and they found same thing, suggesting a
validation of their findings.
Critics will point out that this sample was limited to boys born before
1999, so the results are only applicable to that U.S. male birth cohort,
and that the study’s cross-sectional design limits inferences on
causality. Another weakness is that the autism diagnoses were parent
reported.
On the other hand, these results are generalizable to US boys age 3-17 born prior to 1999; vaccination status was confirmed through medical records; and there was controlling for confounders that may be associated with care seeking behaviors. (The P-value equaled 0.032) The full manuscript is currently under review by another journal.
Assuming that the full manuscript is published in a peer-reviewed journal, it will be among the first university-based population studies to suggest an association between a vaccine and an increased risk for autism. And that would be in direct contradiction to all those MMR and thimerosal studies that purportedly found no such link.
Does that mean that Hepatitis B vaccine causes autism? Of course not (though any relative risk above 2.0 is general considered to prove causation in a US court of law).
But there are other studies, both published and greatly anticipated,
which might support a hypothesized causal association between HepB
vaccine and ASD, at least in boys.
Any day now, data culled from CDC's
Autism and
Developmental Disabilities Monitoring network (ADDM), is expected
to be published in the Morbidity and Mortality Weekly Report, and the
numbers are expected to put the rate of autism at around 1 in 100, or
higher.
ADDM researchers examine the education and (when possible) medical
records of all eight-year-old children in selected US cities and states.
They look only at eight-year-old cohorts to allow time for all diagnoses
to be made, reported and counted.
So far, ADDM has published data from just two birth cohorts: children
born in 1992 (eight-year-olds in 2000) and those born in 1994
(eight-year-olds in 2002). The 1992 cohort revealed an estimated ASD
rate of one in 166, or 60-per-10,000. (This has since been revised to
67-per-10,000, or one in 150).
But CDC data for the same six ADDM locations showed an increase in ASD
from 6.7 for 1992 births to 7.4 for 1994 births.
And now the total average number expected to exceed 100-per-10,000 for
the 1996 birth cohort, born just two years later. The overarching
question, of course, will be, "why?"
There are many possible explanations, though a 50% increase in just two
years is astonishing, no matter what its cause.
One possible answer is the Hepatitis B vaccine, (which also contained 25
micrograms of mercury containing thimerosal up until 2002). Introduced
in 1991, it was the first vaccine ever given on a population basis to
newborn babies (within the first three hours after delivery) in human
history.
But according to the CDC's National
Immunization Survey, only 8% of infant children received the Hep B
vaccine in 1992, when that birth cohort showed an ASD rate of 1-in-150.
By 1994, the number of children receiving Hep B vaccine at birth had
reached just 27% --and the same cohort showed a 10% ASD increase in
locations where both years were measured.
But by 1996, Hep B coverage rate had risen to 82%. And that is the
cohort whose ASD rate rose to around 100-per-10,000 or more.
Correlation, obviously, does not equal causation. But the uptake rate of
that particular immunization is at least one environmental factor that
did demonstrably change during the period in question.
In addition, some recent studies and vaccine
court decisions have supported the contention that Hepatitis B
vaccine can damage myelin -- the nervous system's main insulating
component -- at least in certain genetically susceptible adults and
infants.
A
study published last October in the journal Neurology found that
children who received the Hepatitis B vaccine series were 50% more
likely to develop "central nervous system inflammatory demyelination"
than children who did not receive the vaccine.
Most of this increase was due to the Engerix B brand of the vaccine,
manufactured by the UK's GlaxoSmithKline. That brand increased the risk
of demyelination by 74%, and patients with confirmed multiple sclerosis
were nearly three times more likely to develop the disorder.
"Hepatitis B vaccination does not generally increase the risk of CNS
inflammatory demyelination in childhood," the authors concluded.
"However, the Engerix B vaccine appears to increase this risk,
particularly for confirmed multiple sclerosis, in the longer term. Our
results require confirmation in future studies."
Let’s hope that future studies of neonatal HebB administration,
demyelinating disorders, and ASD are completed as quickly as possible.
David Kirby is author of Evidence of Harm, a founding contributor to Huffington Post and a contributor to Age of Autism. His next book, Animal Factory: The Looming Threat of Industrial Pig, Dairy, and Poultry Farms to Humans and the Environment will be released within the year and is available now for pre-order at Amazon.