In The Know: Immunizations

April 06, 2011
By Dr. Vince Yamashiroya

Dr. Vince Yamashiroya would like to thank the executive committee of the Hawaii chapter of the American Academy of Pediatrics in helping him clarify the content of this article.

Dr. Vince Yamashiroya
General pediatrician

Where did you receive your schooling/training?

I attended the John A. Burns School of Medicine and completed my pediatric residency at the University of Hawaii in 1999. Since then I have been in private practice. I am an associate professor of pediatrics at UH. I am also a fellow of the American Academy of Pediatrics (AAP) and board-certified fellow of the American Board of Pediatrics.

Can you give a short overview on immunizations?

Universal immunizations of children are our greatest tool in preventing life-threatening contagious childhood diseases. Immunizations have been so successful that younger parents are not familiar with devastating diseases such as polio and measles, and may not even recognize illnesses like chickenpox.


What do you tell parents who are concerned about any possible risks involving vaccinations?

Currently, there have been false, unscientific statements made about vaccines causing autism. The three areas of concern regarding whether vaccines could cause autism or any other serious diseases are the following: First would be the measles, mumps and rubella (MMR) vaccine; second would be thimerosal, which is a mercury preservative, and third would be whether giving too many vaccines at one time can overwhelm the immune system and potentially cause autism.

Can you go more into depth on those three points?

No. 1: The measles vaccine. This idea that the MMR vaccine causes autism came about from Dr. Andrew Wakefield in England. In 1998 he published a study in the journal Lancet saying that the measles, mumps, rubella vaccine caused inflammatory bowel disease and autism. As a result, parents in the U.K. and Europe became scared and stopped vaccinating their children, and several outbreaks of measles and mumps occurred. Since that study, there has been a lot of research to determine if the MMR vaccine did cause autism. What they found was that it did not. In fact, when doctors started to look at Dr. Wakefield’s study, they found it was seriously flawed. Out of 13 co-authors in Dr. Wakefield’s study, 10 agreed that the results were wrong and retracted their support. Just last year the editors of Lancet retracted the paper, and the United Kingdom’s General Medical Council took away Dr. Wakefield’s license. There was also a report by the Institute of Medicine in 2004 which concluded that there is no association between MMR and autism, and Brian Deer, a British journalist, wrote a three-part series exposing Dr. Wakefield’s fraudulent research in the British Medical Journal in 2011.

Dr. Vince Yamashiroya checks the ear of patient Kayla Heiss, 15 /Nathalie Walker photo .(JavaScript must be enabled to view this email address)

No. 2: Thimerosal. It has been used since the 1930s to prevent bacterial contamination in multidose vials that were used in immunizing children. Concerns were raised whether children might be receiving dangerous levels of mercury found in vaccines, since we know that methyl mercury that is found in fish, and the environment is toxic to the brain and nervous system in high doses. The thought is that because vaccines contain mercury, it might be good to take it out of the vaccines. As a precaution, in 1999 vaccine manufacturers took it out of all vaccines with the exception of some influenza vaccines. But thimerosal is not methyl mercury, it’s ethyl mercury. Research on ethyl mercury/thimerosal shows that it is eliminated from the body much more quickly than methyl mercury. Research has also unequivocally shown that thimerosal does not cause autism. Some states have banned thimerosal from the vaccines, but autism rates are still going up. Some people wonder whether methyl mercury and ethyl mercury could be similar, but it’s the same thing as ethanol and methanol: Ethanol is what we drink in wine and beer, but if we were to drink even small quantities of methanol, we would probably die. Though both molecules are mercuries, the ethyl in the mercury makes a big difference.

No. 3: Do too many vaccines at one time overwhelm the immune system and cause autism? Some doctors recommend alternative schedules such as spreading out the vaccines. The recommended vaccine schedule is made by a group of experts in infectious diseases and doctors who deal with children, not by pharmaceutical companies. The goal is to make sure the vaccines are given at the earliest possible age when the body will develop immunity to the diseases it is meant to protect us from and at an age when a child is most vulnerable to life-threatening complications. Some people wonder whether giving too many vaccines at one time could potentially overwhelm the immune system. The truth is babies are exposed to germs called antigens every day. The number of antigens children are exposed to is around 2,000-6,000; however, the amount of antigens in the entire vaccine schedule is only 150! If you compare the amount of germs that children are exposed to every day, it’s much more than what are in the vaccines, and their immune system can easily handle that.


Do we know what causes autism?

No, we do not. The leading thought is it’s due to genetic causes. It could be environmental, but we’re not too sure what type of environmental causes there might be. We know for sure from all of the studies looking specifically at vaccines that the vaccines do not cause autism.

Is there a cure for autism?

Currently, there is no cure for autism, but as we are actively seeking the cause of autism, we are hopeful that early screening, diagnosis and intervention programs can help autistic children function better. Our AAP recommends screening all children for autism at 18 months and 2 years of age. The earlier we send these children to early intervention, the better the outcome.

Any final thoughts?

If someone is worried about vaccines, good resources would be the Centers for Disease Control and the AAP. Dr. Paul Offit, a vaccine expert in Philadelphia, has written two books on vaccines: Deadly Choices and Autism’s False Prophets. Also, your own pediatrician or family practice doctor is an excellent resource on vaccine safety.

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