In 2017, researchers from the Yale Child Study Center published a retrospective case-control study in Frontiers in Psychiatry that considered a possible association between prior vaccination and increased incidence of seven neuropsychiatric disorders, including OCD. Recall that at the start of the 1980s, children received three vaccines for seven illnesses (totaling two dozen doses by age 18), whereas fully vaccinated children now get almost six dozen doses for sixteen conditions.
The Yale researchers looked at a national sample of privately insured children and adolescents (ages 6-15) for the six-year period from January 2002 through December 2007. They found that for four diagnoses—OCD, anorexia nervosa, anxiety disorder and tic disorder—the affected children were more likely than matched controls to have received a flu shot in the preceding 12 months. In addition:
For OCD, flu shots just three or six months prior also increased the risk.
There was an association between OCD and hepatitis A vaccination.
Children with OCD, anorexia or a tic disorder were more heavily vaccinated overall compared to children without these disorders.