The Genetic Centers of America, Silver Spring,
Maryland 20905, USA. mgeier@erols.com
We were initially highly
skeptical that differences in the concentrations of thimerosal in
vaccines would have any effect on the incidence rate of
neurodevelopmental disorders after childhood immunization. This study
presents the first epidemiologic evidence, based upon tens of millions
of doses of vaccine administered in the United States, that associates
increasing thimerosal from vaccines with neurodevelopmental disorders.
Specifically, an analysis of the Vaccine Adverse Events Reporting System
(VAERS) database showed statistical increases in the incidence rate of
autism (relative risk [RR] = 6.0), mental retardation (RR = 6.1), and
speech disorders (RR = 2.2) after thimerosal-containing diphtheria,
tetanus, and acellular pertussis (DTaP) vaccines in comparison with
thimerosal-free DTaP vaccines. The male/female ratio indicated that
autism (17) and speech disorders (2.3) were reported more in males than
females after thimerosal-containing DTaP vaccines, whereas mental
retardation (1.2) was more evenly reported among male and female vaccine
recipients. Controls were employed to determine if biases were present
in the data, but none were found. It was determined that overall adverse
reactions were reported in similar-aged populations after
thimerosal-containing DTaP (2.4 +/- 3.2 years old) and thimerosal-free
DTaP (2.1 +/- 2.8 years old) vaccinations. Acute control adverse
reactions such as deaths (RR = 1.0), vasculitis (RR = 1.2), seizures (RR
= 1.6), ED visits (RR = 1.4), total adverse reactions (RR = 1.4), and
gastroenteritis (RR = 1.1) were reported similarly after
thimerosal-containing and thimerosal-free DTaP vaccines. An association
between neurodevelopmental disorders and thimerosal-containing DTaP
vaccines was found, but additional studies should be conducted to
confirm and extend this study.