A significant number of children diagnosed with autism spectrum disorder suffer a loss of previously-acquired skills, suggesting neurodegeneration or a type of progressive encephalopathy with an etiological basis occurring after birth. The purpose of this study is to investigate the effectof the age at which children got their first Measles-Mumps-Rubella (MMR) vaccine on autism incidence. This is a reanalysis of the data set, obtained from the U.S. Centers for Disease Control and Protection (CDC), used for the Destefano et al. 2004 publication on the timing of the first MMR vaccine and autism diagnoses.
The author embarked on the present study to evaluate whether a relationship exists between child age when the first MMR vaccine was administered among cases diagnosed with autism and controls born between 1986 through 1993 among school children in metropolitan Atlanta. The Pearson’s chi-squared method was used to assess relative risks of receiving an autism diagnosis within the total cohort as well as among different race and gender categories.
When comparing cases and controls receiving their first MMR vaccine before and after 36 months of age, there was a statistically significant increase in autism cases specifically among African American males who received the first MMR prior to 36 months of age. Relative risks for males in general and African American males were 1.69 (p=0.0138) and 3.36 (p=0.0019), respectively. Additionally, African American males showed an odds ratio of 1.73 (p=0.0200) for autism cases in children receiving their first MMR vaccine prior to 24 months of age versus 24 months of age and thereafter.
The present study provides new epidemiologic evidence showing that African American males receiving the MMR vaccine prior to 24 months of age or 36 months of age are more likely to receive an autism diagnosis. …
The results show a strong relationship between child age at the administration of the first MMR and autism incidence exclusively for African American boys which could indicate a role of the vaccine in the etiology of autism within this population group. This particular analysis was not completed in the original Destefano et al.  (CDC) study. Although the previous study considered MMR timing and African Americans in general, no statistically significant effect was observed. This is in contrast to our result for African Americans in general, because the CDC study limited the total African American cohort to include only those individuals who possessed a valid State of Georgia birth certificate which decreased the statistical power of their analysis. Although a statistically significant relationship between first MMR age and autism incidence was seen in the general (all races) population within the earlier Destefano et al.  study, the coauthors interpreted this result as an artifact of “healthcare seeking behavior” citing that autistic children would receive their vaccines earlier in order to enroll in State of Georgia early intervention programs. However, it is highly unlikely that this type of behavior would be seen exclusively in African American males and thus, alternative hypotheses must be explored, including the possibility that the MMR vaccine may be causally linked to autism in African American males.
It should be noted that a recent publication has shown that the prevalence of autism in African Americans is nearly 25% higher than that of whites . This value was obtained when CDC data were appropriately analyzed based on socioeconomic status. This could be due to issues regarding vitamin D status with African Americans as it has been estimated that vitamin D sufficiency among whites is between 30-60% but is only 5-10% among African Americans . Patrick et al.  have very recently proposed a mechanism for the link between vitamin D status and autism via selective production of serotonin in the brain. Disruption of the serotonergic system is a very consistent observation with autism  as serotonin promotes prosocial behavior and proper assessment of emotional social cues .
Vitamin D has a multitude of other physiological functions in vivo. Vitamin D receptor has been found in many different tissues including the small intestine, colon, osteoblasts, activated T and B lymphocytes, islet cells and most organs in the body . Vitamin D has also been implicated in many important physiological processing including modulation of activated T and B lymphocyte function [21,22] and prevention of inflammatory bowel disease . Lower vitamin D status African American females are more susceptible to lupus . Also, Epstein-Barr Virus antibody titers are significantly higher in African American youth as compared to compared to white youth  which may be a consequence of vitamin D insufficiency. Also, childhood adversity, which could be more prevalent in African American boys, can have lasting immune consequences .
Gallagher et al.  have reported previously regarding the Hepatitis B vaccine and autism in neonates, specifically within the 1997 to 2002 time period when this vaccine series still contained thimerosal. Regarding non-whites they specifically stated in the abstract, “Non-white boys bore greater risk” of receiving an autism diagnosis if they received the Hep B as neonates. The data reported in this paper show a statistically significant risk ratio of 5.53 (p = 0.019) for black boys as opposed to white boys who had a risk of 1.87 (p = 0.171) which was not statistically significant, when looking at autism in those infants that received their first Hep B vaccine during the first month of life. …
The present study provides new evidence of a statistically significant relationship between the timing of the first MMR vaccine and autism incidence in African American males. Using a straight-forward, Pearson’s chi-squared analysis on the cohort used in the Destefano et al.  (CDC) study, timing of the first MMR vaccine before and after 24 months of age and 36 months of age showed relative risks for autism diagnoses of 1.73 and 3.36, respectively. Future studies should be completed to further evaluate the relationship of first MMR timing and neurodevelopmental maladies, including autism, especially in underserved populations.
Routine childhood vaccination is considered an important public health tool in reducing the morbidity and mortality associated with infectious diseases. However, consideration should be made in the current United States vaccination schedule for genetic subpopulations that may be associated with vaccine adverse events. Additional research is required to better understand the relationship between MMR exposure and autism in African American males.
The abstract for the 2004 study which generated the dataset used here is at: http://pediatrics.aappublications.org/content/113/2/259.abstract