WASHINGTON – Vaccines are becoming more common all the time. They are preventing more diseases and saving more lives. But some people worry that they are doing more harm than good for a number of children.
Some parents and organizations such as the National Autism Association think the current vaccine schedule and some chemicals in vaccines could be too much for newborns and might contribute to neurological disorders such as autism. Nearly all doctors say,however,that these vaccines are essential to protecting children from diseases and do not pose a threat to their health.
The Centers for Disease Control and Prevention recommends that children receive vaccines against 14 diseases in 25 inoculations (22 injections and three by mouth) before the age of 2. A newborn's immune system is capable of handling this many doses,said Dr. Paul A. Offit,chief of the Division of Infectious Diseases at the Children's Hospital of Philadelphia,at a briefing Wednesday for the Congressional Biomedical Research Caucus.
“The feeling that that's more than they can handle is understandable,” Offit said. “But vaccines are a minimal contributor to immune system challenges.”
Offit said he thinks the current vaccine schedule for children is best because extending the vaccine schedule over more time could make children susceptible to potentially fatal diseases,including whooping cough and measles.
Some people are concerned about the chemicals used in vaccines,such as aluminum and thimerosal,but Offit said there is no link between these chemicals and autism,citing six studies focusing on thimerosal that showed the rate of autism was the same for children who had been injected with it and those who had not. He also cited 10 studies that found children who receive the measles,mumps and rubella vaccine have the same rate of autism as those who do not get the vaccine.
Thimerosal is a preservative that staves off bacteria and contains mercury. Both substances were removed from vaccines in 2001 as a precautionary measure,said Curtis Allen,a spokesman on vaccines for the CDC.
“Even if only 50 children were affected,it would easily be picked up in these studies,” Offit said.
He said these studies are not a certainty,but they are close.
“You can never prove never,” Offit said. “But you can say with confidence that a truth has emerged.”
He also said that aluminum should not be a concern because there is less aluminum in vaccines than people are naturally exposed to on earth.
Aluminum salts are used in some vaccines to stimulate the immune system and make the vaccines more effective.
Offit said some people are concerned that vaccines are causing autism because autism usually develops about the same time that children receive these vaccines.
Some research and advocacy groups have also found links to vaccines and autism in studies done on animals such as primates and mice,but Offit said studies done in laboratories based on animals do no always equate to the same results in humans.
“If I was the parent of a child with autism,I would be angry that these groups are devoting so many resources to this,” Offit said. “There are so many more promising leads.”
Research suggests autism might be caused by genetic mutations and a mixture of other problems,including exposure to the drug thalidomide – which is banned in the U.S. – or viruses such as rubella in the womb,that are different for each child,according to Offit's new book. “Autism's False Prophets: Bad Science,Risky Medicine,and the Search for a Cure,” is set to come out this fall.
But many groups think the evidence is clear that these vaccines could be harmful,such as the National Autism Association,a sponsor of the Green Our Vaccines Rally that took place in Washington June 4. The rally was led by actors Jenny McCarthy and Jim Carrey advocating safer vaccines.
McCarthy's son developed autism when he was 2 ½,and she has said she thinks vaccines are to blame.
Some groups are concerned that overwhelming such a small body with so many vaccines before the brain has finished developing could be too much for infants. Newborns begin receiving shots the day they are born,said Rita Shreffler,executive director for the National Autism Association.
Shreffler said she is also concerned with the mercury and thimerosal was used in some vaccines and aluminum,which is still used.
Shreffler's two children,born in 1992 and 1993,both developed autism when they were about 18 months old. It was shortly after they got the MMR vaccine and the diphtheria,tetanus and pertussis vaccine,and she said she thinks the mercury in the DTP shot was too much for her children to handle.
Shreffler's children,now teenagers,are able to live in society. Shreffler said she is not sure if they will ever be able to live independently,but the signs are promising.
“Now we are seeing this could probably work out,” Shreffler said.
The DTP vaccine was recently made into a safer version,the DTaP,because a small number of children experienced serious reactions to the DTP,such as fevers,seizures and brain damage.
Beginning in the early 1990s,children were routinely injected with vaccines containing mercury,which collects in the brain,Shreffler said. Mercury can cause permanent damage to the nervous system and kidneys.
Shreffler said it is common sense that when infants are injected with neurotoxins,which can damage to the nervous system,there could be a wide range of problems.
These include impaired speech and autism,childhood bipolar disorder or attention deficit hyperactivity disorder,she said.
She cited a study done by the University of Washington that showed some primates injected with the same vaccine schedule as infants had signs of autism at a young age. It is important to do more research,she said.
“If you can ascertain what's going on biologically,then you can address treatments accordingly,” she said.
But not all autism awareness groups agree. Autism Speaks takes a more neutral stance on vaccines,saying there is not enough research to support that vaccines lead to autism,according to the group's Web site.
The CDC,which tests and regulates vaccines for safety along with the Food and Drug Administration,recommended that thimerosal be removed from vaccines in 1999. In 2001,it was removed from all vaccines except for flu shots,which contain a trace amount,Allen said.
At the time,there was no evidence to prove a link between thimerosal and autism,but the CDC recommended its removal as a precautionary measure.
The CDC also discovered that,according to some regulations,the amount of thimerosal in vaccines was more than recommended,Allen said. Thimerosal had been in vaccines since the 1940s.
After the CDC recommended that thimerosal be removed from vaccines,studies came out proving that there is no link between vaccines and autism,Allen said.
“We don't believe that thimerosal causes autism,but the bottom line is we don't know exactly what causes autism,” Allen said.
The CDC is continuing to test vaccines for safety and is also researching the cause of autism.
“We are parents,and we certainly consider ourselves advocates for public health and the health of children. It really is a devastating issue for parents of children with autism,” Allen said.