GlaxoSmithKline removes the mercury containing preservative from childhood vaccine due to parents fears over safety.
The company is Europe's biggest pharmaceutical company and, like most drug makers, has for a long time added the mercury containing preservative thimerosal to its vaccines to promote the growth of bacteria and fungi.
However, the company now plans to begin selling a new formula of its Pediarix vaccine for children that does not contain thimerosal. Pediarix is a 5 in 1 combination vaccine given in three doses at 2, 4, and 6 months of age, and is designed to protect infants from diphtheria, tetanus, polio, whooping cough and hepatitis B. It is the only combination vaccine approved by the Food and Drug Administration (FDA) in the US and has been on the market in its original formulation since 2003, with around 21 million doses having been given since then.
Parents, advocacy groups, and some doctors and autism researchers have for many years now raised questions about the safety of adding a mercury containing preservative to childhood vaccines. Mercury and other heavy metals are prime suspects in the search for environmental triggers that might play a role in the development of autistic spectrum disorders. Although drug makers and much of the medical establishment maintain that no hard evidence of such a link exists, it will be reassuring to many parents that the suspect ingredient is to be removed from the Pediarix vaccine.
Jennifer Armstrong, a spokeswoman for the drug maker, told the Dallas Morning News that Glaxo had removed trace amounts of the preservative in its new Pediarix formula and plans to phase in the new products "in the near future."
"Our re-formulation has been made in response to public concern," she explained.
This is certainly not the first time such a move has been made by a pharmaceutical company. In 1999 as thimerosal fears reached a high, US authorities made the recommendation that drug makers should start voluntarily reducing or removing thimerosal entirely from their vaccines. The FDA has been working with vaccine manufacturers to achieve this goal. Other countries have made similar moves. In the UK thimerosal (thiomersal) was removed from all vaccines in 2004.
Early indicators of how these measures have affected autism rates have been mixed.
A study published in the Journal of American Physicians and Surgeons in March 2006, reported a significant drop in new cases of autism in California after thimerosal was removed from vaccines. Using the US government's own databases, independent researchers analyzed reports of childhood developmental disorders, including autism, before and after removal of mercury-based preservatives. The researchers discovered that autism rates in California hit an all time high in 2003 but new diagnoses have since decreased by an impressive 22% as thimerosal use in childhood vaccines has been phased out.
On the other hand a Dutch study much, often referred to by sceptics of the thimerosal-autism link, found that even after the preservative was removed from vaccines, the numbers of children affected by autism continued to rise. So it seems at present there is no definitive answer either way in terms of the effect thimerosal-free vaccines are having on autism rates.
The fears over thimerosal, or more specifically mercury, stem from the metal's inherent neurotoxicity, i.e. it's ability to damage the brain and nervous system. Medical authorities have always said that the amounts that children are exposed to through the thimerosal in their vaccinations couldn't possibly harm them. Others disagree with this presumption however.
In fact, prior to the recommendations in 1999, the FDA itself released a report stating that children who followed the US vaccination schedule and were given thimerosal containing vaccines each time, may have been exposed to more mercury than is recommended by government guidelines. In fact, children may have been receiving 100 times the 0.1 micrograms per kilogram of daily exposure considered safe by most authorities worldwide.
New research is also placing doubt on classical toxicology theory that states that poisons only become toxic after a certain dose is reached and that the toxicity increases in a linear fashion as the dose increases. Scientists are now finding that substances can often be more toxic at low doses than at high doses, and that they can have entirely different effects on health at various doses. Heavy metals have been shown to have these kinds of effects. See our story on this research.
According to the US Environmental Protection Agency's (EPA) website, methylmercury (the form in thimerosal) is the most toxic form of mercury, and "the primary health effect of methylmercury is impaired neurological development". The website also states that the fetus and young children are most at risk from methylmercury exposure.
Jill James, PhD, a researcher at University of Arkansas has carried out research that shows autistic children have a specific vulnerability to the harmful effects of mercury exposure. She has found that autistic children have a genetic predisposition that means they produce less of the amino acids methionine and cysteine, and less glutathione, a major antioxidant protein, than healthy children. These substances are crucial for the detoxification and removal from the body of a multitude of toxins, including heavy metals such as mercury. Low levels could theoretically lead to a build up of methylmercury in the children's bodies and an increased risk of neurological damage. Indeed, other researchers have found that autistic children have higher levels of mercury in their bodies than healthy children, suggesting either a greater exposure to mercury or an inability to remove it from the body, or both. James' research findings have also been replicated by many other researchers.
So although the jury is still out on thimerosal's role in autism, it seems there is plenty of evidence to warrant suspicion and a precautionary approach. It's therefore satisfying to see that pharmaceutical companies and governments are acknowledging safety fears and continuing to take steps to remove thimerosal from vaccines.
The FDA has approved Glaxo's request to change labeling for the new formulation of their Pediarix vaccine after certifying that it is now free from thimerosal and other preservatives. This new formulation should be available to the public shortly.
The Pediarix vaccine with it's 5 in 1 design is evidence of continuing moves towards vaccinations against multiple diseases in a single shot. Although this may be easier for children and their parents, these combination vaccines may carry risks of their own. Some believe that vaccinations against multiple pathogens at the same time or over a short period may cause immune-dysfunction and themselves result in autism, as well as Gulf War syndrome and other unexplained illnesses. Indeed Glaxo's own Pediarix website states that the combination vaccine causes more adverse reactions, such as flu-like symptoms, than single vaccine shots. This however, is is a story for another day!