(Photo courtesy of the CDC)

by Sue Ann Rybak

– The second of a two-part series on the vaccination controversy.

Recent concerns about vaccine safety have caused many parents to decide not to vaccinate their children.

In the 1990s, because of concerns about the increasing number of vaccines containing thimerosal, an ethyl mercury-containing preservative used to prevent contamination of multi-dose vials of vaccines, the Centers for Disease Control and Prevention (CDC) urged manufacturers to remove thimerosal from vaccines.

In 1999, as a precautionary measure, the Public Health Service (including the Food and Drug Administration (FDA), National Institutes of Health (NIH), CDC and Health Resources and Services Administration (HRSA) and the American Academy of Pediatrics issued two joint statements, urging vaccine manufacturers to reduce or eliminate thimerosal in vaccines as soon as possible.

This reaction triggered a flurry of media and other organizations to allege a cover-up by the CCD and vaccine manufacturers regarding the link between autism and thimerosal.

Although thimerosal was taken out of childhood vaccines in 2001, autism rates continue to go up, which is the opposite of what would be expected if thimerosal caused autism.

“There was a number of vaccines in the late 1990s that contained preservatives like thimerosal, and as we added more and more vaccines that contained thimerosal to the schedule, the concern was that maybe we were giving children too much mercury and were inadvertently causing mercury toxicity,”said Dr. Paul Offit, chief of Division of Infectious Diseases and director of the Vaccine Education Center at Children’s Hospital of Philadelphia. “As a precaution, the decision was made by the CDC, by the American Academy of Pediatrics, to ask pharmaceutical companies to take thimerosal out of the vaccines.”

Offit said it precipitated the notion that thimerosal was doing harm.

“The problem is mercury never sounds good,” Offit said. “Given that mercury is in the environment, anybody who lives on this planet and drinks anything made from water, including breast milk and infant formula, are exposed to larger qualities of methyl mercury, which is the environmental mercury.

“It is much more dangerous and lives much longer in the body. Mercury is a neurotoxin at high quantities, but we all have mercury in our bodies because we live on the planet earth. We just don’t have quantities that are dangerous and that is also true in vaccines.”

Offit said that that the majority of vaccines do not contain thimerosal, with the exception of the flu vaccine. He added that there are thimerosal-free flu vaccines.

“It’s a non issue,” Offit said. “The scientific data confirms that thimerosal doesn’t cause autism.”

The Institute of Medicine’s Immunization Safety Review Committee concluded in its report entitled “Vaccines and Autism” that thimerosal does not cause autism, nor does the MMR vaccine.

The report stated that “the body of epidemiological evidence favors rejection of a causal relationship between the MMR (measles, mumps, rubella) vaccine and autism” as well as a “rejection of a causal relationship between thimerosal-containing vaccines and autism.”

The hypothesis that the MMR vaccine was associated with autism was originally proposed in a highly publicized series of case reports published in 1998 in The Lancet, an international medical journal. The authors suggested that the onset of the symptoms of autism with gastrointestinal problems was temporally associated with the receipt of the MMR vaccine.

According to the CDC and the FDA, measles, mumps, and rubella (MMR) vaccines do not and never did contain thimerosal. Varicella (chickenpox), inactivated polio (IPV), and pneumococcal conjugate vaccines have also never contained thimerosal.

Study Retracted

In 2004, ten of the thirteen authors of that study formally retracted their suggestion of a possible link between MMR vaccine and autism in a journal article.

The report went on to say that more recent epidemiological studies, which were analyzed in a recent Institute of Medicine study, have consistently shown no evidence that the MMR vaccine was associated with autism.

“Five large studies in Sweden, Denmark, the United States and the United Kingdom consistently found no evidence of an association between thimerosal and autism,” the report stated.

In a study published in 2003 in the Journal of the American Medical Association by Anders Hviid, that researched Danish children between 1990 and 1996 found that the number of children with autism increased after thimerosal was removed from vaccines.

Weighing the risks

“No vaccine can give you the disease,” said Susan W. Nordlof, a nurse practitioner at Mt. Airy Pediatrics.

Nordlof said that the MMR vaccine prevents measles and two other viral diseases – mumps and rubella. She said MMR is a weakened live-virus vaccine.

Nordlof said that after the injection, the virus grows and causes a harmless infection in the vaccinated person with very few, if any, symptoms.

“The person’s immune system fights the infection caused by these weakened viruses by producing antibodies,” Nordlof said. “So, if you run into them again you’re prepared to fight them off. What I tell kids is it’s a superpower for their utility belt so they have the tool to fight that germ.”

Offit said,“the odds are that you’re going to get chicken pox and survive it and be fine,” “However that virus will live in your nervous system, and when you get older – 60, 70, 80 years of age – it might reactivate and cause shingles,” he said. “Shingles is not something you would wish on your enemy. It’s enormously painful and lasts a long time. If you get the vaccine, the weakened virus will also live in your nervous system, but if it reactivates it is much less severe and lasts for less time.

Offit said that before the chicken pox vaccine was introduced in 1995, 70 to a 100 people died each year from chicken pox.

“Most of those people were previously healthy children,” he said. “So, why take the chance? Why play Russian roulette? Even if there are a 100,000 empty chambers with one bullet, why do it?”

For more information about vaccines, go to www.chop.edu/service/vaccine-education-center