Study: Vaccinations Associated with Neurodevelopmental Disorders in 9-Year-Old Children

A study by A.R. Mawson and B. Jacob titled “Vaccination and Neurodevelopmental Disorders: A Study of Nine-Year-Old Children Enrolled in Medicaid” posted on 23 January 2025 finds evidence of vaccines being associated with neurodevelopmental disorders.

The paper is 23 pages long. The main text is about 20 pages, the remaining are acknowledgements and references. The study aimed to determine whether:

1. vaccination is associated with autism spectrum disorder (ASD), hyperkinetic syndrome, epilepsy or seizures, learning disorders, encephalopathy, and tic disorders. 2. vaccination coupled with preterm birth increases the odds of neurodevelopmental disorders (NDDs) compared to preterm birth without vaccination. 3. increasing numbers of visits for vaccinations are associated with increased risks of ASD.

Data was extracted from Florida Medicaid of children who were born between 1 January 1999 and 31 December 2002 and enrolled for 9 years. There are 42,032 (89.1%) vaccinated children and 5,123 (10.9%) unvaccinated children (or at least no claims of vaccination on the database). Of the aforementioned:

• For full-term births – 37,540 (89.1%) vaccinated and 4,606 (10.9%) unvaccinated.

• For preterm births – 4,492 (89.7%) vaccinated and 517 (10.3%) unvaccinated.

It should be noted there is a higher proportion of males (52.5%) with African-Americans making up the majority of the sample at 39.2%.

Regarding the first aim of whether vaccination is associated with the relevant disorders,

…27.8% of vaccinated children compared to 11% of unvaccinated children had been diagnosed with at least one NDD (OR 3.12, 95% CI: 2.85, 3.41; p < 0.0001).

Figure 2 reproduced below shows the breakdown.

Figure 2: Odds ratios of NDDs by vaccination status in 9-year-old Medicaid children.

Regarding the second aim, it is even worse for preterm births as seen in Figure 3 reproduced below.

Figure 3: Odds ratios of NDDs by vaccination status in 9-year-old Medicaid children born preterm.

Regarding the third aim, increase in vaccinations is “associated with significant increases in the likelihood of diagnosis with ASD” as seen in Figure 4 reproduced below. It can be seen there is little difference between 1 visit and 4 visits but the risk does increase at 5 or more visits.

Figure 4: Relative risks of the diagnosis of ASD and increasing numbers of visits that included vaccinations.

There are obvious limitations to the study. Although the sample is sufficiently large, the analysis relies on codes on the Florida Medicaid database. Setting aside possible errors, it is possible for children to be vaccinated outside this system and therefore misrepresented as unvaccinated. In any case, at least in a generalized manner,

[t]he results of this study add to a growing body of evidence suggesting that vaccination may be associated with significantly increased odds of various medical conditions, including NDDs.

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