Childhood Immunization and Thimerosal

Edith Umland , M.D.

Medical Epidemiologist, Office of Epidemiology

12-1999

Several (though not all) vaccines currently recommended for routine immunization of infants an children contain a preservative, thimerosal, which contains ethyl mercury as the active antibacterial and antifungal component. Thimerosal is added to vaccines supplied as multidose vials to prevent contamination of the vaccine which could cause infections at the site of injection. (See Table 1)  for mercury content of vaccines administered to infants). Recently published recommendations for maximum mercury exposure may be met or exceeded by the total amount of mercury administered in thimerosal containing vaccines. This has prompted us to modify our recommendations regarding childhood immunizations. This situation has occurred because of recent development of exposure guidelines for mercury and the increasing availability of vaccines for protection of young infants.

Vaccination of children against serious pathogens has been one of the greatest public health achievements. Vaccinations have reduced dramatically both mortality and morbidity of children and adults (See Figure 1). We have also learned in recent years that when immunization rates drop, these same diseases make a comeback. We still experience significant morbidity and mortality from pertussis, Haemophilus influenzae infections, varicella and others. The New Mexico Department of Health, the US Public Health Service, and the American Academy  of Pediatrics strongly recommend the continued vaccination of young children against diphtheria, tetanus, pertussis, Haemophilus influenzae b and polio, with completion of vaccine series at the earliest age compatible with recommendations.

Background:  The concern over mercury in vaccines is part of an increasing trend to try to minimize exposures to environmental toxins, such as lead and mercury. Mercury binds to body tissues and is not rapidly excreted. For people without occupational exposure, about half of the mercury absorbed comes from food, (mostly fish) and half comes from dental amalgam. Mothers transfer some mercury from their body to their babies, both before birth (across the placenta) and through breast milk. No one knows if there is a “safe” level below which there is no risk of any adverse effect. With respect to neurological effects of mercury, the fetus and young infant will be the most vulnerable because of rapid development of the brain and brain function. Guidelines for exposure to various sources of mercury have been developed by FDA, EPA.

Table 1 Mercury content of vaccines administered to infants

Codes

1 (if not combined with DTP or DtaP containing thimerosal)

2 from DtaP (Tripdeia) component

3 contains formaldehyde (().02%) and 2-phenoxyedthanol (0.5%) preservatives

4 all live virus vaccines are thimerosal-free

Notes:

--Other vaccines, not usually administered to children under the year of age may contain thimerosal.

--Thimerosal is contained in immune globulin (iG) but not in hepatitis B immune globulin (HbiG).

Mercury in Infant Shot Raises Concerns by Jackie Jadrnak (Albuquerque Journal Staff Writer) undated

Concerns about small amounts of mercury used in vaccines have led the state to scale back by one the number of immunizations it is recommending for newborn and small infants.

Health experts hastened to add that there is no evidence that any babies have been harmed by the mercury , which is used as a preservative in some vaccines. There’s as much (mercury) in a tuna fish sandwich as in one dose of vaccine,” said Dr. Gary Overturf, professor of pediatrics at the University of New Mexico. Overturf serves on the infectious disease committee of the American Academy of Pediatrics, which struggled in recent weeks to come up with recommendations on the vaccines.

Part of the problem is that no one knows for sure exactly what level of mercury might harm a small infant, whose nervous system still is developing. Mercury can cause neurological problems.

The state Department of Health on Thursday told parents they should consider delaying their babies Hepatitis B immunizations until the babies are a year old or until a mercury free vaccine is developed. Hepatitis B is a disease carried by a  virus that can cause liver damage, and can be transmitted through the bodily fluids of an infected person…..