Backsliding on Childhood Immunization

Vaccines are the ultimate public health weapon: they prevent disease, target specific conditions and demographic groups, are highly cost-effective, and lend themselves to campaigns reaching broad populations. Not surprisingly, vaccines against HIV and malaria, which to date have defied scientific and technological know-how, are among the “holy grails” of current medical research.

Effective vaccination against measles, which has been available since 1963, has controlled this disease in many countries, transforming it from a threat that ravaged entire populations to a minor risk very seldom resulting in death. Measles was declared eliminated in the U.S. in 2000. Recently, however, the country has witnessed a resurgence of the disease. Outbreaks have been reported in nine states, with 64 reports of confirmed measles cases during the first four months of 2008, the highest number for the same period since 2001. Ten of these cases acquired measles abroad; the remaining cases are linked to the imported cases.

Of the 64 persons infected by the measles virus, only one had been vaccinated. Of the remaining 63 cases, 14 were infants too young to be vaccinated. Another 16 were children whose parents claimed exemption from mandatory vaccination because of religious or personal beliefs.

The distrust of vaccines has been the result of a controversial issue which has been debated for fully a decade: whether or not there is an association between vaccines and autism. This was largely prompted by a 1998 article published in The Lancet which suggested that the combined MMR (measles, mumps, rubella) vaccine might be linked to increases in autism. The aftermath of this finding was more important than its initial publication. Ten of the 12 of the article’s original authors disavowed the connection and signed a retraction of the study’s conclusions in 2004. In addition, the study’s lead author, who defended the original conclusion, has since been accused of accepting money from people claiming harm from the MMR vaccine. He has therefore been undergoing a disciplinary hearing by the body that licenses physicians in Britain. Nevertheless, he has devoted followers who accuse the General Medical Council of conducting a witch-hunt against one of their own.

In the U.S., any association between vaccines and autism has been repeatedly refuted by many studies and scholars. Because the presumed culprit in any adverse effect was thimerosal, a mercury-containing preservative used in some vaccines, a number of studies have focused on this ingredient. But several studies examining trends in vaccine use and changes in the prevalence of autism do not support such an association. In addition, a scientific review by the Institute of Medicine (IOM) in 2004 concluded that “the evidence favors rejection of a causal relationship between thimerosal-containing vaccines and autism.” The CDC supported the conclusion. While the evidence was being gathered, in July 1999 the agencies of the U.S. Public Health Service, the American Academy of Pediatrics, and vaccine manufacturers agreed that thimerosal should be reduced or eliminated as a precautionary measure. Recent data from California show that autism rates have continued to rise even after thimerosal was eliminated from childhood vaccines, thereby reinforcing the IOM’s conclusions.

Still, many parents are not reassured, and many are not immunizing their children with the MMR vaccine, with predictable consequences. Resurgence in measles is thus part of the price that has been paid as a result of faulty science leading to the wrong prescriptions.