The autism wars aren't over -- but they may have entered a new phase.
Autism Speaks, the nation's largest autism advocacy group, recently made its clearest public statement yet that minimizes the link between vaccines and autism.
In a prepared interview posted on the Autism Speaks Web site, the group's chief science officer, Dr. Geri Dawson, says that scientific studies have found no link between thimerosal, a mercury preservative used in certain vaccines, and autism. Nor have they found a connection between the measles-mumps-rubella vaccine and autism.
"So ... given what the scientific literature tells us today," she says, "there is no evidence that thimerosal or the MMR vaccine cause autism" and "evidence does not support the theory that vaccines are causing an autism epidemic."
Dr. Dawson's statement still allows for the possibility that reactions to vaccinations might cause autism in a small subset of children, but it seems to go further than ever before in ruling out vaccines as a major trigger for the neurodevelopmental disorder.
The Autism Speaks pronouncement comes at a time when some parents have stopped inoculating their children or are spreading out their shots, to the consternation of public health officials, who fear the resurgence of such childhood diseases as measles and whooping cough.
Much of the parents' resistance to immunization has been driven by fear that vaccines can cause autism, a disorder that affects an estimated 1 out of 150 children. Autism is characterized by poor social and communication skills, repetitive behaviors, fixation on certain interests and, in some cases, retardation.
A spokeswoman for Autism Speaks said Dr. Dawson did not want to be interviewed about her latest statement, and contended it is not a new position for the organization.
But several scientists and others who have been involved in the autism debate said her views, which were posted July 30, are a clear departure from past statements, and probably reflect the ongoing tug-of-war over the vaccine issue.
Dr. Neal Halsey, director of the Institute for Vaccine Safety at the Johns Hopkins Bloomberg School of Public Health in Baltimore, said the new position is "two steps in the right direction. This is a substantial change and improvement in Autism Speaks in acknowledging that vaccines do not cause autism, and that the evidence is overwhelming that neither the MMR vaccine nor thimerosal in vaccines causes autism."
Still, Dr. Halsey said he wishes Dr. Dawson would have emphasized that thimerosal no longer is used with vaccines given to children under 6 months of age, because "unfortunately, parents still fear they might be causing their children some harm by getting their kids vaccinated."
Thimerosal, an organic mercury compound, was used for decades as a preservative in multidose vials of some vaccines to keep them from being contaminated when needles were repeatedly inserted into them. It has now been removed from all childhood vaccines except some versions of the flu vaccine.
The MMR vaccine scare came primarily from a study done in the United Kingdom about a decade ago that suggested the measles portion of the vaccine caused intestinal inflammation that led to autism. Later studies failed to confirm those findings.
While federal agencies have pushed manufacturers to remove thimerosal from as many vaccines as possible, many scientists say it never posed a threat to children's health.
A 2007 study of more than 1,000 children between the ages of 7 and 10 who had been exposed to varying amounts of thimerosal during vaccinations and other treatments found no link between the preservative and any cognitive or language problems, for instance.
None of the studies, however, have swayed one group of parents and activists who believe that vaccines are a major cause of autism, particularly in children who appeared to be developing normally before they got their vaccinations.
One of those activists is Katie Wright, who has an autistic child and is the daughter of Robert and Suzanne Wright, the founders of Autism Speaks. Although she is not a part of Autism Speaks, Ms. Wright said in a 2007 interview that her parents support her view that environmental toxins of some sort trigger autism.
She said her father, the former CEO of NBC Universal, "believes there is a place for genetic research, but he realizes the dire need to finance the environmental research because that is what affects our children now."
Because of pressure from people like Ms. Wright and groups that believe vaccines are dangerous, officials at Autism Speaks are pulled in two directions, said Kristina Chew, the parent of an autistic son and a blogger on autism issues who does not believe vaccines cause the disorder.
"On the one hand," said Dr. Chew, a classics professor in New Jersey, "they do want to promote science. On the other hand, they want to be an organization for families and parents, and I think they're caught there, because what some of the parents see is their children getting vaccines and then becoming autistic overnight."
Many other families of autistic children "feel the vaccine issue is overblown," she said, "but they are afraid to articulate that in public because the response from the other side can be very hateful and extreme."
While anti-vaccine groups continue to lobby Autism Speaks, the organization may also have been influenced from the opposite direction by the recent resignations of two key people.
Dr. Eric London, a New York psychiatrist whose National Alliance for Autism Research merged with Autism Speaks three years ago, resigned from Autism Speaks' scientific affairs committee this year, saying that the group's argument "that there might be 'biologically plausible' vaccine involvement [in autism] is misleading and disingenuous."
In an interview last week, he said he thinks Dr. Dawson crafted her new position statement because "the organization was getting a fair amount of pushback from myself and other people and even the press, and this wasn't happening a year or two ago, and so I think they're trying to position themselves as not being too unreasonable."
On the other hand, he said, "if they're going to continue to link to the anti-vaccine people [on the Autism Speaks Web site], it's all just spin. They're certainly not delivering a consistent message."
Another top official who resigned is Alison Tepper Singer, who was executive vice president of Autism Speaks and is a member of the federal government's Interagency Autism Coordinating Committee, which sets goals for federal research on autism.
"When you keep saying more research needs to be done on vaccines it sends the wrong message," said Ms. Tepper Singer. "We have a really good amount of data on vaccines and autism. At some point you have to say we're done and we're going to use our scarce resources elsewhere."
She and Dr. London's wife, Karen London, recently established the Autism Science Foundation, a charity that has pledged it will not support any research on vaccines and autism.
The biggest fear some experts have is that the controversy is already endangering the health of youngsters and adults whose parents are refusing to vaccinate their children.
The immunity children acquire from their mothers starts to wear off at about 6 weeks of age, said Dr. Nancy Minshew, director of the University of Pittsburgh's Center for Excellence in Autism Research.
That's one reason the diphtheria-pertussis-tetanus vaccine is given at a young age, she said, because "those illnesses can kill babies."
The measles-mumps-rubella vaccine, given at about 1 year of age, is equally important, Dr. Minshew said, and not just for the children themselves.
If pregnant women and their fetuses are exposed to rubella, also known as German measles, it can cause deafness, heart and liver problems, retardation and even autism in the children after they are born. If children get mumps and spread it to a man who doesn't have immunity, it can cause sterility.
For all these reasons, it's important for parents to follow the recommended vaccination schedule, she said.
"There used to be entire classrooms of kids who had become deaf from measles," Dr. Minshew said. "I have male relatives who never could have kids because of mumps. People today don't see the results" of those infections, and that may make them blase about the importance of vaccinations.
"When it comes to immunization, who are you going to listen to? I'm going to listen to the researchers who are the best of the best, and what they say is that immunizations do not cause autism, but they do save lives," she said.
Mark Roth can be reached at firstname.lastname@example.org or at 412-263-1130.