Facts about the Measles (MMR) Vaccine | UCLA Health

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As measles cases continue to increase nationwide following an outbreak at Disneyland, doctors are urging parents to learn the facts about the Measles Mumps and Rubella (MMR) vaccine.

27 counties in California still have dangerously low kindergarten vaccination rates, and statewide the percentage of kindergartners with personal belief exemptions has been rising steadily since 2002.

Dr. Dennis Woo, a pediatrician at UCLA Health Santa Monica, has been fielding calls from worried parents.

“I am convinced that most people make this decision not based on fact but on feeling.” Dr. Woo said, adding those feelings are influenced by what parents have heard from friends.

Carrie Swearngin, mother of a two year old boy, said she has friends who urged her not to vaccinate her son Samuel.

“They were in our ear about it a little bit,” she said.

Friendly advice aside, what does the scientific evidence actually show about the safety of the MMR vaccine?

“Facts are that many studies have been done to look at the safety of vaccines, and they’re looking at large populations of children and it’s been determined that… autism is not caused by the MMR.” Dr. Woo said.

The American Academy of Pediatrics has a detailed list of those studies with links to the published results.

Among them, the Centers for Disease Control (CDC) conducted a study comparing rates of vaccination among thousands of children, some of whom had autism, and others who didn’t have autism. The study found similar rates of vaccination between the two groups.

Other studies have looked at the effects of thimerosal (mercury), a vaccine preservative that some parents believed caused autism.

A scientific review by the Institute of Medicine (IOM) found no connection between thimerosal-containing vaccines and autism. Nevertheless, in 2001 thimerosal was removed or reduced to trace amounts in all childhood vaccines except for one type of influenza vaccine, for which alternatives without thimerosal are available upon request.

“We effectively have removed mercury or thimerosal from all the children’s vaccines and we have not seen any drop in autism. So clearly, autism is not caused by thimerosal,” Dr. Woo said.

Other parents voice a concern about kids getting too many vaccines at once, and whether all of them are needed.

A 2013 study published in the Journal of Pediatrics looked at this concern of “too many vaccines too soon.” The study examined the medical records of about a thousand children, how many vaccines they got, and found no connection between the number of vaccines they got, and whether they developed autism. Researchers also note that the amount of antigens (immune stimulating material) in modern vaccines is much lower than those in older vaccines used in the 1990’s.

“Children’s immune systems are well suited to be able to tolerate all that,” Dr. Woo said.

The MMR and autism scare was sparked by a 1998 study by British surgeon Dr. Andrew Wakefield, which linked the MMR vaccine to autism. The study involved only 12 children. The British Medical Journal launched an investigation into the study and found numerous problems in the way it was conducted. It also found that Wakefield was paid $600,000 by lawyers trying to sue vaccine manufacturers. Ten of the 13 author withdrew their support for the study’s conclusions.

In 2010, the medical journal Lancet completely retracted the study. A British medical panel concluded that Dr. Wakefield had been dishonest, and violated basic research ethics rules. British regulators revoked his medical license, saying he was guilty of “serious professional misconduct.”

After weighing the evidence, Swearngin went ahead and got her son vaccinated.

“He’s all set,” she said. “We’re of the mind frame to listen to the doctor.”

The current MMR recommendation is that children get the first shot at 12-15 months of age, and the second shot between 4-6 years of age. Dr. Woo said that if your child is up to date on the first MMR shot, there is no need to get the second shot early, unless there was a known exposure to measles.

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