A controversial 1998 study that falsely suggested possible links between childhood vaccines and autism – and has since been widely discredited and retracted – nonetheless helped drive a rise in the number of parents who opted not to give their kids the recommended MMR (measles, mumps, rubella) shots, new research shows.
University of Cincinnati researchers found widespread media reports on the dubious 1998 study led to a decline of about 2 percent in vaccination rates for children in 1999 and 2000. Even after many later studies thoroughly refuted the questionable MMR-autism research, the drop off in vaccination rates persisted.
Lead researcher Lenisa Chang, who is slated to present the findings at an upcoming Conference of the American Society of Health Economics, examined data from the National Immunization Survey from 1995 through 2006 to gauge parents' response to the controversy.
In addition to finding a drop in MMR vaccination rates immediately following the 1998 study's publication in The Lancet (which later retracted the research), Chang reported declines in vaccination rates in 2003, 2004 and 2006 – even after the original research was discredited and more definitive studies found no evidence of a link.
She also found the controversy had a spillover effect to other vaccines likely as a result of safety concerns.
"The spillover effect I find on other vaccines such as polio and, to a lesser degree DTP (diphtheria, tetanus and pertussis), could be partially ascribed to general safety concerns toward all vaccines that stemmed from the MMR controversy, but other factors might be at play as well," Chang said.
The original 1998 study involved just 12 children with autism and never actually concluded vaccination caused the condition, but merely suggested more research be conducted after noting the patient’s symptoms developed after they received the MMR shots.
“We did not prove an association between measles, mumps, and rubella vaccine and the syndrome described,” they stated flatly.
After its publication, 10 of the 13 coauthors on the report disowned the research paper, fearing it could damage public health efforts.