CDC Updates Vaccine-Autism Stance, Prompting Maryland Health Department Response

Following an update to its vaccine safety webpage, the Centers for Disease Control and Prevention (CDC) has acknowledged that scientific studies have not definitively ruled out a potential link between infant vaccines and autism. This shift in messaging has prompted a response from the Maryland Department of Health (MDH), which maintains that there is no credible scientific evidence supporting such a connection. The CDC’s revised statement indicates that the claim “vaccines do not cause autism” is not evidence-based, citing a lack of studies that have conclusively disproven the possibility. The Department of Health and Human Services (HHS) has also launched a comprehensive assessment into the causes of autism, including investigations into biological mechanisms and potential causal relationships.

The CDC’s updated stance stems from obligations under the Data Quality Act, which requires federal agencies to ensure the quality, objectivity, utility, and integrity of the information they disseminate. The agency noted that while the statement “vaccines do not cause autism” has historically been used to address vaccine hesitancy, scientific research has not established the absence of a link. The HHS assessment will inform future updates to the CDC webpage with findings from rigorous scientific inquiry.

According to the CDC, historically, the prevalence of autism has risen concurrently with the increase in the number of vaccines administered to infants. While autism is understood to be multifactorial, the CDC’s revised perspective suggests that the scientific basis for completely excluding vaccines as a contributing factor has not been established. One analysis highlighted in the CDC’s update pointed to aluminum adjuvants in vaccines as having a statistically significant correlation with the rise in autism prevalence among other suspected environmental factors, underscoring the need for further study, though correlation does not equate to causation.

The National Childhood Vaccine Injury Act of 1986 mandated a review of scientific and medical information concerning the relationship between pertussis-containing vaccines and various conditions, including autism. Subsequent reviews by HHS and the National Academy of Sciences’ Institute of Medicine have consistently found insufficient evidence to establish or reject a causal relationship between certain infant vaccines and autism. These reviews have indicated that studies have not supported the claim that infant vaccines such as DTaP, HepB, Hib, IPV, and PCV do not cause autism, leading to the conclusion that the CDC’s previous assertion was not evidence-based.

The Maryland Department of Health, through its Secretary Dr. Meena Seshamani, has emphasized the critical role of vaccines in public health.

Vaccines remain one of the most powerful public health tools we have to keep ourselves, our families and our communities healthy and safe from disease. Vaccines in the U.S. are vigorously tested and monitored for safety.

There is no credible body of scientific evidence that shows an association or link between vaccines and autism. People with autism deserve understanding, respect, inclusion, and support. It does a disservice to them, the progress we have made in understanding autism, and public health as a whole when these types of unsubstantiated claims are made.

The Maryland Department of Health is committed to broad vaccine access in our state. We will continue to take steps to make sure Marylanders can access vaccines when they need them, and practice careful and evidence-based decision-making for public safety and disease prevention.

Maryland Department of Health Secretary Dr. Meena Seshamani

Reviews of the evidence concerning the MMR vaccine have generally concluded, with a high degree of certainty based on observational data, that there is no association with autism spectrum disorders. However, some studies examined in these reviews have been criticized for methodological limitations. Furthermore, the CDC noted that retrospective epidemiological studies cannot definitively prove causation and may not account for potential vulnerable subgroups or mechanistic links. Differences in vaccination schedules between countries, such as the United States and Denmark, are also a consideration when evaluating study results.

The presence of aluminum in some infant vaccines has also been a point of discussion. While the MMR vaccine does not contain aluminum, other infant vaccines can have varying amounts. An analysis of the 2019 CDC vaccine schedule indicated a significant total exposure to vaccine-related aluminum by 18 months of age. Some research has suggested a positive association between vaccine-related aluminum exposure and persistent asthma in the U.S., and a Danish cohort study, while not showing an increased risk for neurodevelopmental disorders overall, indicated potential higher event rates for neurodevelopmental conditions with moderate aluminum exposure and a statistically significant increased risk of Asperger’s syndrome per incremental increase in aluminum exposure among certain birth cohorts. These findings suggest that further investigation into aluminum exposure and its potential impact on various childhood chronic diseases, including autism, is warranted.

HHS plans to further investigate plausible biological mechanisms that could link early childhood vaccinations with autism. Areas of focus for this research include the effects of aluminum adjuvants, risks for children with mitochondrial disorders, and the impact of neuroinflammation.

Article by Ken Buckler, based upon information from the Centers for Disease Control and Prevention and the Maryland Department of Health

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