MIAMI, Florida, USA: Testimony in Washington DC next month will revisit the controversial issue of whether childhood vaccinations have connection with autism.

Republican Florida Representative Dave Weldon, a physician by trade, has pushed to have the hearing postponed, arguing that "it does not appear to be a serious effort to examine these critical issues."

Weldon and others worry that the Institute of Medicine, part of the National Academy of Sciences, will reach premature conclusions and short-circuit important research that will be completed later this year.

"The national vaccine programme has saved millions of lives and millions of kids from disability," he said. "When we have questions raised, it's very important to get them thoroughly evaluated and not just try to sweep them under the rug."

The one-day hearing in Washington on February 9 will tackle two questions: Could thimerosal, a mercury-containing preservative used in many vaccines in the 1990s before manufacturers voluntarily phased it out, have triggered autism in genetically susceptible children?  Could the measles-mumps-rubella (MMR) vaccine, which has never contained thimerosal, trigger autism?

The controversy takes place as the number of autistic children appears to be rising dramatically across the United States, and many in the medical community worry that unfounded fears could cause parents to shun vaccinations for their children, leaving them vulnerable to deadly diseases.

Autism has no known cause and no cure. Researchers around the US are exploring possibilities besides vaccines, from a genetic link to environmental factors such as pesticides, PCBs, flame retardants and chemicals used in industrial processes.

Weldon recently sent a letter to Julie Gerberding, director of the US federal Centers for Disease Control and Prevention, urging her to postpone the meeting until at least the end of this year or early 2005, after additional research is completed.

The Institute of Medicine is conducting the hearing at the CDC's request. As of the afternoon of January 23, Weldon had received no response.

Safe Minds, a New Jersey-based group that seeks to reduce mercury exposure in children, also sent a letter voicing similar concerns.

"Currently, numerous investigations are under way that would offer much additional science to the debate," wrote Safe Minds' president, Lyn Redwood. "... Holding a hearing at this time, with little new data, is a waste of taxpayer dollars."

A CDC spokesman, Von Roebuck, said that the meeting would proceed as planned and should shed light on an important topic. "This is an opportunity to gather a lot of information," he said.

The Institute of Medicine's Immunisation Safety Review Committee typically holds a hearing on a question, analyses the available studies and scientific literature and then releases a report with its findings and recommendations a few months later, said an IOM spokeswoman, Christine Stencel.

The Institute is a private organisation created by the US federal government to serve as an independent adviser on health-related issues.

Critics question the meeting's timing, speculating that the goal may be to have the Institute come out with a report rejecting the possibility of a vaccine-autism link as class-action lawsuits wind through the courts.

"I'm very suspicious of that," Weldon said. "... What better way to try to head this all off at the pass than to get the Institute of Medicine to issue a report (rejecting an autism-vaccine link)?"

Weldon added that, if the Institute rushed to judgment, "they could end up with egg on their face three or four years from now. Ultimately, the research will come out."

The lawsuits centre on thimerosal, a mercury-containing preservative used in several vaccines until the US Food and Drug Administration asked manufacturers in 1999 voluntarily to phase it out of children's shots. Thimerosal can still be found in children's vaccines outside the United States.

The Institute of Medicine weighed in on the autism-vaccine controversy in 2001 by concluding there was no evidence of a connection between MMR and the disorder.

Questions about a link between MMR and autism first surfaced in 1998, when the British gastroenterologist, Dr Andrew Wakefield, noted that eight autistic children had developed an unusual inflammation in their intestines and appeared to regress shortly after receiving the MMR vaccine.

The Institute of Medicine, in a second report released in 2001, called for additional studies on thimerosal. The Institute concluded that it was "biologically plausible" that vaccines containing thimerosal could cause neurodevelopmental disorders in children." It said there was no evidence that this had occurred, but there was also insufficient evidence to rule it out.

Since those reports, several high-profile studies have cast doubt on an autism-vaccine link, including a look at 500,000 children born in Denmark between 1991 and 1998. That study found no difference in the level of autism among children vaccinated with MMR and those who were not.

Last year, a CDC study published in the journal, Pediatrics, concluded that "parents should be reassured that quantities of mercury, aluminum and formaldehyde contained in vaccines are likely to be harmless on the basis of exposure studies in humans or experimental studies in animals."

But critics have taken aim at both studies and researchers around the country have other analyses under way.

The controversy heightened when Safe Minds, after obtaining documents through a Freedom of Information Act request, revealed that a CDC researcher had initially found a statistically significant association between exposure to thimerosal-containing vaccines and developmental delays, and had then revised his methodology and found none in his final report issued in 2000.

Safe Minds also noted that a short time later, the researcher, Thomas Verstraeten, had gone to work for the vaccine-maker, GlaxoSmithKline, in Belgium.

Weldon argues that much of the research is being driven by the CDC's National Immunisation Programme office, which has a vested interest in the outcome. "These people are essentially investigating themselves," he said.

Weldon stressed that he remained a vaccine supporter. He had administered many vaccinations while practising medicine and his five-year-old son had received all of the recommended shots, he said.

But Weldon added that it was important that an outside entity, with no connection to the CDC, oversaw studies on vaccines and autism. "My desire is to get at the truth and maintain public confidence in the vaccine programme. In my honest opinion, we have gotten very little research done on these questions."

(Source: Contra Costa Times, January 26, 2004)