Assuaging parents' fears of MMR vaccine

Donya Betancourt, Pediatrician, drdonya@hotmail.com

The debate over the relationship between the measles-mumps- rubella (MMR) vaccine and autism goes on.

Today, I have two reliable sources from London and Denmark about the MMR vaccine. The question is, does widespread use of the vaccine coincide with an increase in incidences of autism?

Various studies in the last four years do not support this association, but many of these studies were methodologically flawed. None had the sufficient statistical power to detect an association and none were population-based.

A study was conducted in Denmark between January 1991 and December 1998, and included all children born in Denmark as reported to the Danish Civil Registration system. Vaccine status was determined by a review of data reported to the National Board of Health -- practitioners in Denmark are required to report this information and are reimbursed by the state on the basis of these reports.

The Danish vaccination program recommends that the first MMR dose be administered at 15 months of age and provides it free of charge. Children were followed until a maximum age of 9 years.

Information about diagnoses of autism was obtained from the Danish Psychiatric Central Register, which contains information on patients diagnosed in hospitals, outpatient psychiatric departments and outpatient clinics throughout Denmark.

In Denmark, only specialists in child psychiatry diagnose autism and assign a diagnostic code for this disorder. An extensive review of records for 40 children with this diagnosis, or 13 percent of all children diagnosed with autism, was conducted to determine if the diagnosis was consistent with the International Statistical Classification of Diseases and Related Health Problems, 10th revision.

A total of 537,303 children were included in the cohort and followed for a total of 2,129,864 human years. Approximately 82 percent of these children were vaccinated.

The study provided strong evidence to finally lay this issue to rest -- not only was the risk of autism similar in vaccinated and unvaccinated children, but there was no temporal clustering of cases of autism around the time of vaccination. These results were derived from a nationwide study with an almost complete follow-up. In addition, the data was collected prospectively, was independent of parental recall and was from a period prior to the diagnosis of autism.

The overall incidence of autism and autism-spectrum disorders found in Danish children in this study was similar to studies on incidence in French children and U.S. children, thus making it unlikely that Danish children were statistically less likely to develop autism.

Today, the latest news from Reuters Health London has warned that in England, more children risked catching measles, mumps and rubella as uptake of the triple MMR vaccine continued to fall.

The agency said its latest figures showed that the MMR vaccine uptake among two-year-olds fell to 78.9 percent in the first three months of the year -- a drop of 2.1 percent from the previous quarter. This followed a similar decrease from 83 to 81 percent in the quarter before.

There were 151 cases of measles, 441 cases of mumps, and four cases of rubella in the first quarter of 2003. Only six of the children who contracted measles had been vaccinated, including one child who had received a single measles jab rather than MMR.

Uptake of the triple vaccine has been falling in the UK for several years after researchers at London's Royal Free Hospital suggested a possible link with autism. The link has been denied by most researchers who have examined the evidence.

Commenting on the latest figures, Reuters Health's Natasha Crowcroft said in a statement, "We are concerned, because as coverage falls, more children are left susceptible to measles, mumps and rubella. We would like to reassure parents that MMR is the safest and most effective way to protect our children."

Crowcroft said research showed that the majority of parents were still confused about the safety of MMR.

"They perceive that medical science gives equal weight to both sides of the argument when in fact, the balance of scientific evidence is overwhelmingly in favor of the vaccine being safe."

After reading this, I hope that all parents will now be aware that unvaccinated children are not the safest children. In my opinion, prevention is still the best choice.