pediatrics
Vaccine Hesitancy
Measles Mumps Rubella (MMR) Vaccine
 that postulated a link between the measles virus in the MMR vaccine and Autism Spectrum Disorders and received significant media attention worldwide; many parents began to doubt the safety of the MMR vaccine. This report concerned 12 children with developmental disorders and gastrointestinal (GI) problems; 9 of them also had Because Wakefield's methodology could show only a temporal association rather than a cause-and-effect relationship, numerous other researchers studied the possible connection between the MMR vaccine and autism. Gerber and Offit reviewed at least 13 large epidemiologic studies, all of which failed to support an association between MMR vaccine and autism ( MMR vaccine references ). Many of these studies showed that national trends of MMR vaccination were not directly associated with national trends in the diagnosis of autism. For example, in the UK between 1988 and 1999, the rate of MMR vaccination did not change, but the rate of autism increased. Other studies compared the risk of autism in individual children who did or did not receive the MMR vaccine. In the largest and most compelling of these studies, Madsen et al assessed 537,303 Danish children born between 1991 and 1998, 82% of whom had received MMR vaccine ( MMR vaccine references ). After controlling for possible confounders, they found no difference in relative risk of autism or other autism-spectrum disorders in vaccinated and unvaccinated children. Overall incidence of autism or an autistic-spectrum disorder was 608 of 440,655 (0.138%) in the vaccinated group and 130 of 96,648 (0.135%) in the unvaccinated group. A follow-up study of all children born in Denmark between 1999 and 2010, for a total of 657,461 children concluded that the MMR vaccine does not cause autism (hazard ratio 0.93 [95% CI, 0.85 to 1.02]) overall, nor does it increase the risk in children who are at high risk of autism because of their family history ( In response to Wakefield's increased detection of measles virus in intestinal biopsy specimens from autistic children, Hornig et al searched for the measles virus in biopsy samples taken from 38 children who had GI symptoms and were having a colonoscopy; 25 children had autism, and 13 did not ( MMR vaccine references ). The measles virus was not detected more often in the children with autism than in those without. fully retracted the 1998 publication based on the findings of the British General Medical Council ( MMR vaccine references ). Three months after Despite the overwhelming evidence to support the safety of the MMR vaccines, and the discrediting of Wakefield's research, many parents remain unconvinced. As a result, the United States experienced the largest number of measles cases in 2019 since 1992. According to the Centers for Disease Control and Prevention (CDC), most infected people were not vaccinated ( MMR vaccine references ). 1.Gerber JS, Offit PA: Vaccines and autism: A tale of shifting hypotheses.Clin Infect Dis48(4):456-461, 2009. doi: 10.1086/596476 2.Madsen KM, Hviid A, Vestergaard M, et al: A population-based study of measles, mumps, and rubella vaccination and autism.N Engl J Med347(19):1477-1482, 2002. doi: 10.1056/NEJMoa021134 3.Hviid A, Hansen JV, Frisch M, Melbye M: Measles, mumps, rubella vaccination and autism: A nationwide cohort study.Ann Intern Med170(8):513-520, 2019. doi: 10.7326/M18-2101 4.Hornig M, Briese T, Buie T, et al: Lack of association between measles virus vaccine and autism with enteropathy: A case-control study.PLoS ONE3(9):e3140, 2008. doi: 10.1371/journal.pone.0003140 5.Eggertson L: Lancet retracts 12-year-old article linking autism to MMR vaccines.CMAJ182(4):E199-E200, 2010. doi: 10.1503/cmaj.109-3179 6.Patel M, Lee AD, Clemons NS, et al: National update on measles cases and outbreaks—United States, January 1–October 1, 2019.MMWR68(40);893–896. doi: 10.15585/mmwr.mm6840e2 