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Reference: Pediatrics 2014 Apr;133(4):e835 (level 3 [lacking direct] evidence)
Childhood vaccination has become a contentious issue for many parents, mostly due to safety concerns, all of which have been discredited. In particular, concerns were raised regarding a perceived increase in the risk of autism among vaccinated children. The measles, mumps, and rubella (MMR) virus vaccine, which is often given to children around the same time as the first signs of autism become apparent, has been the target of several anti-vaccination campaigns. Although the original study positing a link between MMR vaccination and developmental disorders has been retracted (Lancet 2010 Feb 6;375(9713):445), and a large body of scientific evidence has consistently shown no link between MMR vaccination and autism, there are still several misconceptions about the safety of the MMR vaccine outside the scientific community. In response, several organizations have developed patient materials that explain the lack of evidence that MMR causes autism. These include the United States Centers for Disease Control and Prevention (CDC) and the American Academy of Pediatrics. A recent randomized trial evaluated several different interventions designed to promote vaccination with the MMR vaccine.
The trial sampled 4,462 adult parents from an online panel and asked them to complete a short interview. A total of 1,759 parents (39.4% of those sampled) with available interview data were randomized to 1 of 5 web-based interventions: text explaining lack of evidence that MMR causes autism (autism correction), text describing dangers of the diseases prevented by MMR (disease risks), images of children who have diseases prevented by MMR vaccine (disease images), a story regarding an infant who almost died of measles (disease narrative), and text about costs and benefits of bird feeding (control). The vaccine promotion interventions were adapted from current public health authority materials.
Compared to the control group, none of the interventions to promote MMR immunization were associated with significantly increased parental intent to vaccinate a future child with the MMR vaccine. Moreover, the autism correction intervention was associated with decreased parental intent to vaccinate a future child (adjusted odds ratio 0.52, 95% CI 0.32-0.84). A subgroup analysis showed that this significant reduction was confined to parents who were least favorable to vaccination at baseline. There were no other significant differences between any intervention vs. control for parental intent to vaccinate with the MMR vaccine.
In the United States, MMR vaccination coverage among children aged 19-35 months was about 91% in 2012 (MMWR Morb Mortal Wkly Rep 2013 Sep 13;62(36):733 full-text). Although the national average exceeded the Healthy People 2020 target of 90%, there were 15 states with MMR coverage below that target, which has raised concerns of higher incidence of these preventable childhood diseases in areas with lower coverage. The CDC observed 159 cases of measles (including 17 hospitalizations) in 2013 (MMWR Morb Mortal Wkly Rep 2013 Sep 13;62(36):741 full-text), with large outbreaks associated with importation of measles from other countries. These outbreaks highlight the continued need for effective vaccination programs. Unfortunately, the findings of this new randomized trial show that current messaging from public health authorities is not effective for the groups least likely to allow vaccination of their children. Alternative initiatives are needed, and future studies evaluating the effect of messaging on childhood vaccination rates are warranted.
For more information see the Measles, Mumps, and Rubella Vaccine topic in DynaMed.