Administration Thimerosal-containing Vaccines
Title: Administration of thimerosal-containing vaccines to infant rhesus macaques does not result in autism-like behavior or neuropathology.
Authors: Bharathi S. Gadad, Wenhao Li, Umar Yazdani, Stephen Grady, Trevor Johnson, Jacob Hammond, Howard Gunn, Britni Curtis, Chris English, Vernon Yutu, Clayton Ferrier, Gene P. Sackett, C. Nathan Marti, Keith Younge, Laura Hewitson, and Dwight C. German.
Date: August 9, 2015.
The article is a study on the effects of a known vaccine preservative – thimerosal (that contains ethyl mercury) – used as an antifungal and antiseptic for vaccines – and its effects on development of autism-like behaviours or neuropathology (abnormal changes in the brain associated with Autism Spectrum Disorders). The vaccines were distributed to 79 infant rhesus macaques (type of monkeys) divided into six groups:
- Control group (injected with saline) – 16 monkeys;
- 1990s Pediatric – 12 monkeys – replicated vaccine schedule for infants in the 1990s (in USA), that included TCVs (thimerosal-containing-vaccines);
- 1990s Primate – 12 monkeys – like above, but accelerated 4-fold (representing faster developmental rate of monkeys);
- TCVs – 12 monkeys – only TCVs and no MMR (measles, mumps and rubella pathogens);
- MMR – 15 monkeys – only the MMR vaccine
- 2008 – 12 monkeys – the expanded pediatric vaccination schedule, similar to the one used today (in USA).
For changes in the brain tissue, only 1990s and 2008 groups were used as the first group had the highest thimerosal exposure and the latter one had the greatest number of different vaccines received and is very similar to current schedule used in USA.
In terms of behavioural changes in macaques – none of the few behavioural patterns typical for autism were noted in significant numbers. The animals were observed between the ages of 12-18 months, 5 days a week, during 5 minutes long focal periods. Animals developed normal range of behaviours for their age group.
Neuropathology of ASD includes abnormalities in density and volume of cerebellum, hippocampus and amygdala regions and number of specific cells – Purkinje cells – all of these were analysed through histopathology and biochemical analyses. No changes in density and volume of cerebellum, hippocampus and amygdala were found. Purkinje cells are often found in lower density or smaller in size in postmortem brains of ASD subjects. In this study, there was no difference in numbers, size or density between control and test subjects’ Purkinje cells.
I am a fervent supporter of childhood vaccines since so many studies and data about public health confirmed that human life expectancy and childhood mortality were significantly improved (for life expectancy) or reduced (for childhood mortality) ever since vaccines were introduced in 1930s in USA. Ever since 1998, the efficacy and safety of the vaccines has been hotly debated, due to a study published by A. Wakefield. Many studies were completed since then to disprove false claims Wakefield and followers have made. This study is one of them and it effectively disproved anecdotal reports that childhood vaccines that contain thimerosal and/or MMR vaccines cause autism. The irony is that the study was funded by big anti-vaccine groups – SafeMinds and National Autism Association and that one of the authors on the long list – Laura Hewitson – was also the author of another, messy and retracted paper (used a very small sample size) on monkeys that caused the whole controversy about purported ‘evidence’ on thimerosal effects (she also worked in a center where Andrew Wakefield used to work (discredited scientist who first suggested that MMR causes autism without any evidence/tests).
References: APA Conestoga