The Causes of Autism

Who are the brilliant authors, what is the full title of the study, and what year was it published?

Authors: Brian S. Hooker and Neil Z. Miller

Title: Health effects in vaccinated versus unvaccinated children,
with covariates for breastfeeding status and type of birth. Journal of Translational Science, Vol 7: 1-11

Year: 2021

What is the study about?

This study analyzes the health outcomes of fully vaccinated, partially vaccinated, and completely unvaccinated children born between 1998 and 2016 from three US pediatric medical practices. The study evaluates the incidence of severe allergies, autism, gastrointestinal disorders, asthma, ADD/ADHD, and chronic ear infections among these populations and aims to investigate the correlation between vaccination status and these conditions.

The lack of studies that compare the health outcomes of fully, partially, and unvaccinated children is highlighted in the paper. The National Academy of Medicine (NAM) has also recognized the need for such studies to assess pediatric vaccination schedule-related health outcomes. NAM has suggested investigating short- and long-term effects of modified vaccine schedules, wherein children receive fewer vaccines than recommended or later than recommended.

What previous research is there on this topic?

The paper discusses studies that suggest a potential link between vaccines and autism. One study found a relationship between vaccination status and neurodevelopmental disorders, including autism. Another study found that children with atypical autism-pervasive developmental disorder or Asperger syndrome were more likely to have received greater mercury exposure during infancy from thimerosal-containing hepatitis B vaccines.

The CDC’s Vaccine Safety Datalink database was recently evaluated, and it was found that children diagnosed with ADHD were significantly more likely than controls to have received greater mercury exposure from thimerosal-containing vaccines within the first 15 months of life. Other studies have also reported an association between vaccines and ADHD.

What methods were used in the study?

Sample Size

The study included 1565 children within the age range, of which 60.4% were completely unvaccinated, 30.9% were partially vaccinated, and 8.7% were up-to-date with vaccines. The study also evaluated the prevalence of health conditions, such as allergies, autism, gastrointestinal disorders, asthma, ADD/ADHD, and chronic ear infections.

Data Analysis

The study utilized a cohort design and logistic regression model to investigate the correlation between vaccination status and various health outcomes, such as severe allergies, autism, gastrointestinal disorders, asthma, attention deficit disorders (ADD/ADHD), and chronic ear infections. Data were analyzed using the SAS® University Edition statistical software package. The study collected patient data through an online voluntary survey instrument from participants in three US pediatric practices, and diagnoses were confirmed through electronic medical records.

Data analysis was performed with and without covariates, such as breastfeeding status and type of birth. Odds ratios and p-values were calculated using Fisher’s exact test on a 2×2 design. After removing children with congenital conditions leading to diagnoses, 1565 children were included in the study from a total of 1929 surveys completed.

What were the findings?

Fully vaccinated versus unvaccinated children, with covariates

Children who were fully vaccinated were found to be significantly more likely to be diagnosed with various health conditions than unvaccinated children. The study identified an increased risk of severe allergies, autism, gastrointestinal disorders, asthma, ADD/ADHD, and chronic ear infections among fully vaccinated children compared to unvaccinated children. However, the analysis also found a protective effect of vaccination against chickenpox.

Partially vaccinated versus unvaccinated children, with
covariates

The study found a significant correlation between vaccination status and the same health conditions (increased risk of severe allergies, autism, gastrointestinal disorders, asthma, ADD/ADHD, and chronic ear infections). The associations were statistically significant, and vaccination was found to be protective against chickenpox.

Vaccinated versus unvaccinated children, no covariates

Once again, all studied relationships are statistically significant and vaccination is protective against chickenpox.

Any vaccine versus unvaccinated children, participating medical
practices only

Vaccinated children were significantly more likely than unvaccinated children to be diagnosed with all health conditions under consideration, and vaccination was protective against chickenpox.

Any vaccine versus unvaccinated children, confirmed diagnoses
only

Vaccinated children were significantly more likely than unvaccinated children to be diagnosed with all health conditions under consideration, and vaccination was protective against chickenpox.

Relationships between vaccination and breastfeeding status

Children who were not breastfed and were vaccinated were found to be significantly more likely to be diagnosed with all the health conditions studied, as compared to children who were breastfed and unvaccinated.

Relationships between vaccination and birth delivery status

Relationships between covariates and all health conditions
under consideration

Children who received vaccines and were delivered via C-section were found to have a higher likelihood of being diagnosed with these conditions compared to unvaccinated children who were delivered vaginally.

Breastfeeding showed a protective effect against allergies, asthma, and ear infections. However, breastfed children were found to have a higher likelihood of contracting chickenpox. For gastrointestinal disorders, a significant association was observed with delivery status, with C-section-delivered children being more prone to such diagnoses.

What are the strengths of this study?

This study has several strengths, including the ability to review electronic medical records to confirm diagnoses provided by parental surveys, mitigating potential recall bias. Only children with confirmed diagnoses were included in the analysis. The study’s use of a positive control with chickenpox diagnosis lends credibility to the study. The study’s findings are consistent with previous research, further supporting its results. Finally, effect estimates in the study were above 4.0, which indicates that a confounding variable would need to be 4 times as frequent in vaccinated children.

What are the study’s limitations?

The main weakness of the study is the use of a convenience sample from only three pediatric practices. The data was obtained through parental surveys, which could introduce both recall and selection bias, limiting the generalizability of the findings. The survey only collected limited demographic data, such as breastfeeding status, type of birth, and current education status, excluding other factors that may affect health outcomes, such as vaccinations during pregnancy and gestational age at birth.

What conclusions can be drawn from the study?

The study suggests a possible association between vaccination status and the incidence of health conditions, including severe allergies, autism, gastrointestinal disorders, asthma, ADD/ADHD, and chronic ear infections. The research found that fully vaccinated children were more likely to be diagnosed with these conditions than completely unvaccinated children. The study also revealed that breastfeeding could reduce the likelihood of allergies, asthma, and ear infections, but increase the chance of having chickenpox. However, the study did not establish causality and could not determine whether vaccination status was the sole factor contributing to the increased incidence of health conditions.

The research underscores the need for additional studies using diverse samples from multiple medical practices to determine the full extent of health effects associated with childhood vaccination. Finally, it is crucial to provide such studies to the public to build trust in vaccination programs, avoid unsupported claims, and improve vaccine policies.

As efforts to increase vaccine coverage rates intensify, unvaccinated populations that are necessary to serve as control groups for monitoring true rates of adverse events related to vaccination are being lost. It is important to maintain such populations to ensure scientific accuracy in monitoring the safety of vaccines.

Can I read the full study somewhere?

You can check it out right here.

Librarian’s Footnotes

Needless to say, this library makes no recommendations regarding the parental right to vaccinate or not-vaccinate their own child, as that decision and responsibility rests upon caretakers themselves. No claims that vaccine hesitancy is promoted through sharing a scientific study assessing this association will be acknowledged or addressed. The responsibility of self-education regarding vaccine safety falls upon each individual, who then relies on various sources of information (sometimes conflicting) for information.

Studies do exist that find no associations between vaccines and autism. It is a heavily debated, albeit not a thoroughly and transparently researched topic. For example, a paper by Mohammed et al. (2022) reviewed 19 studies studying the association between vaccines and autism and indicated no causal relationship could be determined. However, Mohammed et al. (2022) did not include several crucial studies in its analysis of papers between 1998 and 2022, such as the study by Mawson et al. (2017), who found a relationship between vaccination and neurodevelopmental disorders (including autism), Geier et al. (2017) who found an association between autism and mercury exposure from thimerosol containing vaccines using the CDC’s Vaccine Safety Datalink data, or Delong (2011) who found an association between neurodevelopmental disorders and vaccines. Future research should explicitly review studies that did find associations between vaccines and autism to further examine the relationship.

An additional perspective is that caregivers themselves are an undervalued source of qualitative data. Most caregivers are privy to the smallest of changes in the health and demeanor of their children, not to mention factors associated with autism diagnosis (i.e., communication, socialization, etc.). There is a potential wealth of data to be obtained from caregivers themselves who are often met with mockery and criticism when attempting to address vaccine safety concerns.