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Vaccines currently recommended during pregnancy include the flu shot and the pertussis vaccine (Tdap). What is the link between prenatal vaccines and autism? This is the question that we will explore.
I would like to tell you a story that has long since been forgotten. In the 1950s and early 1960s, a new 'miracle' drug was being prescribed to pregnant women around the world to treat, among other issues, morning sickness. The company that produced and sold the drug claimed that it was completely safe even during pregnancy. Sadly, tragedy ensued as countless babies were born with birth defects. Even those who are familiar with this story may not be aware that children born to mothers who took the drug during days 20-23 of gestation, when "the neural tube is closing and the first neurons are being born," had a significantly increased risk of autism. The drug in our story was Thalidomide and the tragedy caused by its use is now a distant memory but it still should serve as a cautionary tale. It appears, however, that the precautionary principle during pregnancy is again being neglected. It is my sincere hope that birth providers take an honest, hard look at the science, or lack thereof, behind prenatal vaccination rather than simply following the recommendations of their governing bodies. Ultimately, however, I believe the responsibility lies with the expectant parents to diligently research more than just car seats and cribs. The interventions that you choose during your pregnancy can and will have a lifelong impact on the health of your child.
Epidemiological data over the past few decades has implicated various maternal bacterial & viral infections, including influenza, as major risk factors for autism spectrum disorder (ASD) in human offspring.[3-7] Mouse studies have shown that the pups of mothers infected with influenza during gestation displayed autistic-like behavior, showed abnormal cortical development and had structural alterations to their cerebellum.[2,8-9] Abnormal cortical growth and cerebellar structure, particularly with regard to the density & structure of the Purkinje cells, are common findings in animals with autistic-like behaviors and humans with ASD.[2,10-19] Cerebellar dysfunction appears to be a major contributor to the cognitive, motor and behavioral challenges seen in ASD, in part, due to the loss or inappropriate migration of Purkinje cells which are believed to inhibit excess excitation within the brain leading to sensory processing challenges.[2,20-21] Cerebellar development accelerates in the late prenatal & early postnatal period and injury to the cerebellum is considered the largest, single non-genetic risk factor for ASD.[21-24] Findings such as these led one prominent vaccine researcher from the Mayo Clinic, Dr. Gregory Poland, MD, to call flu shots "anti-autism vaccines."
In 2004, the Advisory Committee on Immunization Practices (ACIP) and the American College of Obstetricians & Gynecologists (ACOG) began recommending the flu shot for all pregnant women regardless of trimester. Prior to 2004, the flu shot was only recommended to women who were in their 3rd trimester during the 'flu season'. Should birth providers be recommending flu shots during every pregnancy? It certainly sounds like a reasonable approach considering that illness in pregnancy is strongly associated with an increased risk of ASD and other neurological challenges in children. However, it is important to note that the effectiveness of the flu vaccine has often been quite poor including during the 2014-15 season. In fact, there is mounting evidence that flu vaccines may increase the risk of influenza and non-influenza respiratory infections.[28-29] Additionally, it is interesting to read the vaccine manufacturers' 2015-2016 package inserts, specifically the section entitled "use in specific populations."
Safety and effectiveness of FLUARIX have not been established in pregnant women or nursing mothers."
"Safety and effectiveness of AFLURIA have not been established in pregnant women or nursing mothers."
"Safety and effectiveness of FLUZONE has not been established in pregnant women."
In 2012, the ACIP also began recommending that all women receive the Tdap (Tetanus, diptheria, acellular pertussis) during every pregnancy between 27-36 weeks gestation in an effort to reduce the risk of whooping cough in vulnerable infants. Prior to 2012, Tdap was only recommended in pregnancy if the mother had not previously received the vaccine. Is the new recommendation a sensible strategy? Tdap vaccination has been shown to increase the levels of maternal pertussis antibodies that pass transplacentally to the fetus & through the breast milk to the newborn providing increased protection following a postnatal challenge with the vaccine-strain of the B. pertussis bacteria.[34-37,67] However, I would like to quote directly from a 2013 CDC document regarding the effectiveness of the current vaccine with regard to a mutated pertussis strain that may be the most common strain circulating in the U.S.:
Findings indicated that 85% of the [pertussis] isolates were PRN-deficient and vaccinated patients had significantly higher odds than unvaccinated patients of being infected with PRN-deficient strains. Moreover, when patients with up-to-date DTaP vaccinations were compared to unvaccinated patients, the odds of being infected with PRN-deficient strains increased, suggesting that PRN-bacteria may have a selective advantage in infecting DTaP-vaccinated persons."
In years past, doctors often recommended getting the flu vaccine and the Tdap vaccine weeks apart, however, that may change due to a recent study concluding that it was just as safe to give both vaccines during the same prenatal visit. The authors of this study admit that they did not look into how the vaccines impact the unborn baby after birth. The following is an excerpt from a 2014 literature review:
The existing safety data regarding maternal vaccination during pregnancy mainly focuses on maternal outcomes, and on early fetal and infant development; long-term follow-up data on the incidence of neurodevelopmental disorders in the offspring of mothers vaccinated during pregnancy is scant."
In their zeal to prevent prenatal infections, in part, to decrease the risk of ASD in human offspring, birth providers and researchers may be neglecting to ask a fundamental question...is it the microbe or the immune activation that leads to the increased incidence of neurological damage? Could indirectly priming the fetal immune system with maternal vaccinations during pregnancy predispose susceptible children to a neuroinflammatory phenotype that results in ASD? The biological research from rodents and non-human primates has shown conclusively that it is the maternal immune activation, not the microbe, that is the cause of the neurological sequelae in the offspring.[41-46]
When the maternal immune system encounters a challenge, whether through a natural infection or a vaccination, the primary immune cells of the central nervous system (CNS), known as neuroglia, become activated and primed. These neuroglia release chemical messengers known as cytokines which function to help eliminate the perceived threat, however, cytokines also play a key role in normal neurodevelopment.[48-52] This flood of maternal cytokines alters cytokine expression in the fetus and, if this occurs with enough intensity during a critical window of neurodevelopment, may lead to abnormalities even in the absence of overt neuroinflammation. Rodent studies have found that prenatal immune activation creates long-lasting alterations in cytokine expression in the fetal brain and can cause a more vigorous response to subsequent immune challenges such as postnatal vaccinations.[53,58,63] Human studies on individuals with ASD show chronic activation of neuroglia particularly within the cerebellum, elevated brain and cerebrospinal fluid (CSF) cytokines, and alterations in the genetic expression of genes governing neuroglia functions.[54-56,59-60] Neuroglial activation is known to promote the death of developing cerebellar Purkinje cells via reactive oxygen species (ROS).
Additionally, mitochondrial dysfunction in the offspring is a known sequela from maternal immune activation during pregnancy. Mitochondrial issues are a recognized problem in a significant subset of people with ASD. Maternal antibodies produced during an immune challenge also have the potential to attack fetal brain proteins resulting in the neurobehavioral changes seen in ASD.[64-66]
You may have noticed that I have made no mention of specific vaccine ingredients that have garnered so much attention in recent years including aluminum, an adjuvant or immune stimulator found in the Tdap vaccine, or thimerosal, an ethyl-mercury containing compound found in some influenza vaccines. I did so to emphasize that maternal immune activation, even in the absence of known neurotoxins, can be problematic for the neurodevelopment of the fetus. If you would like more information on the dangers of thimerosal, I recommend Eric Gladen's new documentary 'Trace Amounts.' Of note, my home state of California passed a law in 2006 banning the administration of flu vaccines containing relatively high levels of thimerosal to pregnant women and young children with a special exemption, that has been granted in 2006, 2009, 2013 and now 2015, based on the following clause:
if the secretary [of Health & Human Services] finds, and the Governor concurs, that...an epidemic or shortage of supply of a vaccine that would prevent children under three years of age and knowingly pregnant women receiving the needed vaccine, making necessary the administration of a vaccine containing more mercury than the maximum level set forth..."
The potential for a maternal immune challenge to create neuroimmunological & neurobehavioral changes in the offspring is dependent on a number of factors including the timing & intensity of the initial immune challenge, the timing & intensity of subsequent immune challenges, concurrent & subsequent exposures to neurotoxins and genetic & epigenetic susceptibilities. Unfortunately, the implementation of universal vaccination during pregnancy fails to consider these factors. In his 2006 article entitled 'Pregnancy, Immunity, Schizophrenia, and Autism,' Dr. Paul Patterson, PhD concludes with this prescient statement:
"And what does vaccination do? It activates the immune system. That's the point of vaccination. In practice, not all pregnant women receive [vaccines], and I think that universal vaccination of pregnant women could get us into a whole new set of problems."