There’s still no evidence to support the claim that an aggressive vaccination schedule in children causes autism, according to the latest research from the Centers for Disease Control (CDC). 

Autism affects as many as one in 50 children, according the latest CDC statistics, and up to one-third of parents believe that the disease can be caused by vaccinations. Because of that, one in 10 parents don’t follow the CDC’s recommended vaccination schedule

But, according to a new study published in the Journal of Pediatrics, there’s still no reputable scientific evidence to support the claim that certain vaccines and how soon they are administered can cause autism.

Examining the Alleged Link Between Vaccinations and Autism

Using data on 256 children diagnosed with autism spectrum disorder and 752 children without the developmental condition, researchers at the CDC and Abt Associates, Inc., assessed each child’s level of exposure to antigens, the part of vaccines that trigger a response from the immune system to fight off a specific disease.

Researchers compared the total number of antigens all the children were exposed to by age two—including the maximum number they may have been exposed to in a single day—and determined that the antigen exposure level was the same across both sets of children.

“These results indicate that parental concerns that their children are receiving too many vaccines in the first two years of life or too many vaccines at a single doctor's visit are not supported in terms of an increased risk of autism,” the study authors concluded.

The study was led by Dr. Frank DeStefano, director of the Immunization Safety Office at the CDC.

How the Autism-Vaccination Claim Gained Traction

The idea that autism is caused by vaccines stems from a now-debunked paper authored by Andrew Wakefield, who submitted research in 1998 claiming that the measles-mumps-rubella (MMR) vaccine was linked to autism. The publication it appeared in has since retracted the article. 

Before the research was dubbed pseudoscience, actress and autism activist Jenny McCarthy led a campaign based on Wakefield’s claims to spread the message that too many vaccines early in life can cause developmental disorders.

One large concern for McCarthy was the use of the substance thimerosal, a mercury-heavy preservative used in many vaccines since the 1930s. However, DeStefano published a study last year saying that infants exposed to the chemical don’t have an increased risk of developing autism.

‘Too Many Shots in a Day’

A concern voiced by many parents is that the total number of vaccines a child receives has increased significantly since the late 1990s. Currently, a child may receive up to seven shots in a single day. 

Researchers said, however, that while children may be getting more shots, the number of antigens they are exposed to has actually decreased since the 1990s, which is why merely counting the number of vaccines a child receives isn’t a good way to judge his or her level of exposure. 

Under the current CDC vaccination schedule, the maximum number of antigens a child is exposed to is 315. In the late 1990s, it was several thousand, researchers said. 

While there’s still no known cause of or cure for autism, researchers continue to strongly assert that there’s no connection between vaccines and autism.

Other Myths About Vaccines

While no one can fault good-natured parents for wanting to do right by their children, vaccinations are often falsely linked to numerous diseases without scientific evidence.

One enduring myth is that flu vaccinations are unsafe for pregnant women. Earlier this year, researchers from the Norwegian Institute of Public Health examined data from pregnancies during the 2009 flu pandemic to determine the safety of flu shots for both the expectant mother and her child.

They found that flu vaccinations do not increase the risk of fetal death, and may actually reduce the risk of death brought on by the flu itself.

Every year, scientists work to create better, more effective vaccines for children and adults. For example, researchers at Mount Sinai Medical Center believe they've found that the flu virus can tell time, and they’re learning how to exploit that to create better vaccines.

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