New Study Shows No Link Between Vaccines and Autism

A study conducted between 2008 and 2014 at the Washington National Primate Research Center showed that vaccines did not cause any brain or behavioral changes in macaque monkeys. The study involved 79 infant male macaques aged 12 months to 18 months who were split into six groups. Two groups received thimerosal-containing vaccines (TCVs) for a child’s complete vaccine schedule; two were given the measles, mumps and rubella (MMR) vaccine without TCVs; and two received saline injections as a control group. In each case, the monkeys were further split into subgroups: half were on an accelerated vaccination schedule recommended by the U.S. Centers for Disease Control and Prevention in the 1990s, and half were on the recommended schedule from 2008. After receiving the vaccines, the monkeys were put together in cages to see if they exhibited any new autistic-like social behaviors such as fear, withdrawal, rocking, self-clasping and stereotypy (repetitive behavior), and it was found that their behavior remained unchanged.

The researchers also conducted postmortem analyses of the primates’ brains, after they had been euthanized, looking for brain abnormalities, including those in the volume and density of the cerebellum, amygdala and hippocampus region, which have been shown to have some variations in children with autism. In addition, they looked at the numbers and size of Purkinje cells since some studies have shown there are fewer of these cells in the brains of children with autism. However, the researchers found no marked differences in the brains of monkeys in the vaccine groups compared with those in the control group.