Question

Vaccines are generally considered to be the most successful public health intervention ever devised, and yet there have been opponents of vaccines ever since there have been vaccines. Many people often spread misinformation about the vaccine, such as the notion that vaccines weaken the immune system and that children can develop autism after getting vaccinated. What is your opinion on the subject? Please provide your input

Answer 1

Perhaps the most common misconception is that a child’s immune system can be “overloaded” if the child receives multiple vaccines at once. This concern first began to appear as the recommended childhood immunization schedule expanded to include more vaccines, and as some vaccines were combined into a single shot. However, studies have repeatedly demonstrated that the recommended vaccines are no more likely to cause adverse effects when given in combination than when they are administered separately.

Some parents decide to “spread out” the time period during which their children receive vaccinations “just in case” this misconception is accurate. However, there is no scientific evidence to support this approach, and delaying vaccinations puts children at risk of contracting preventable diseases.

Do Immunizations or Thimerosal Cause Autism?

No. Numerous studies have found no link between vaccines and autism (a developmental disorder that's characterized by mild to severe impairment of communication and social interaction skills). Likewise, a groundbreaking 2004 report from the Institute of Medicine (IOM) found that thimerosal (an organic mercury compound that's been used as a preservative in vaccines since the 1930s) does not cause autism.

Still, some parents have opted not to have their children immunized, putting them at great risk of contracting deadly diseases.

The MMR vaccine, especially, has come under fire even though many scientific reports have found no evidence linking the vaccine to autism. In fact, the study that suggested a possible link between autism and the MMR vaccine was retracted in 2004 and the doctor who published it lost his medical license. Even before it was discredited and declared fraudulent, the study was rejected by all major health organizations, including the AAP, the National Institutes of Health (NIH), the Centers for Disease Control and Prevention (CDC), and the World Health Organization (WHO).

There's also no reason to believe that thimerosal is linked to autism, according to the 2004 IOM report. Still, in an effort to reduce childhood exposure to mercury and other heavy metals, thimerosal began being removed from kids' vaccines in 1999. Now, vaccines for infants and young children contain no or very little thimerosal. And recent studies have not shown any cognitive and behavioral problems in babies who might have received these thimerosal-containing vaccines.

So what could explain the increased rates of autism in recent years? For one thing, there's a broader definition of autism that can be applied to more kids who show varying degrees of symptoms. A greater awareness of the condition among health professionals also has led to more diagnoses.

And although the number of children diagnosed with autism may be increasing, the rates of MMR vaccination are not. In London, diagnoses of autistic disorders have been on the rise since 1979, but rates of MMR vaccination haven't increased since routine MMR vaccination began in 1988.

Also, the average age of diagnosis of autism has been found to be the same both in children who have and who have not received the MMR vaccine. What many researchers are discovering is that subtle symptoms of autism are often present before a child's first birthday — sometimes even in early infancy — but often go unnoticed until the symptoms are more obvious to parents.