On July 7, 1999, the American Academy of Pediatrics (AAP) issued a joint statement with the Centers for Disease Control and Prevention (CDC) alerting clinicians and the public to concern about thimerosal, an organic mercury-containing antibacterial preservative in some vaccines. These concerns were based on an FDA review which found that cumulative thimerosal exposure from all routine immunizations in the first 6 months of life could exceed some government- recommended limits.
A significant safety margin exists in current mercury exposure
limits. The mercury content of vaccines given to children
6 months of age meets FDA standards for intermittent
exposures but exceeds EPA standards for prolonged daily exposure. There is no
evidence of harm due to mercury in vaccines given to young children, nor is
there any need to test for mercury exposure. The CDC and AAP jointly remind
clinicians that the known risks of vaccine-preventable infections are far more
serious than any risks from vaccinating children according to the recommended
schedule.
The only change that the practitioner may wish to consider is giving the first dose of hepatitis B virus (HBV) vaccine not at birth, but at 2 months of age, when the infant is considerably larger, unless the new thimerosal free vaccine is used. Preterm infants born to HbsAg-negative mothers should receive HBV vaccine when they reach term gestational age and a weight of at least 5.5 lbs (2.5 kg). This temporary schedule adjustment should apply only to infants born to HbsAg-negative mothers; vaccination just after birth is still needed by infants born to HbsAg-positive mothers and in populations where HbsAg screening of pregnant women is not routinely performed. On August 27, 1999, a single-antigen preservative-free hepatitis B vaccine (Recombivax® HB, Merck & Co., Inc.) was licensed. (See also: Notice to Readers: Availability of Hepatitis B Vaccine That Does Not Contain Thimerosal as a Preservative MMWR 48(35):780-782, Sep. 10, 1999)
Additional information on this topic is available at the CDC website or in more detail at the AAP website. The AAP website has a list of vaccines containing thimerosal.
Thimerosal in vaccines: a joint statement of the American Academy of Pediatrics and the Public Health Service, MMWR 48(26):563-565, 1999.
Recommendations regarding the use of vaccines that contain thimerosal as a preservative, MMWR 48(43):996-998, Nov. 5, 1999.
Keeping Current on Vaccine Recommendations
See Chapter 10 in Essentials of Pediatric Nursing, 5th edition.
See Chapter 12 in Nursing Care of Infants and Children, 6th edition.
March 15, 2002