Use of Hepatitis B Vaccines Related to Thimerosal in Vaccines - Q & A The American Academy of Pediatrics (AAP) has received a number of queries regarding the recommendation for hepatitis B vaccination. These queries arose following recent recommendations released in the AAP interim report which discusses thimerosal in vaccines. (see September 1999 Policy Statement entitled Thimerosal in Vaccines—An Interim Report to Clinicians)
The AAP recommendations for prevention of hepatitis B virus infection are as follows: For infants born to HBsAg-positive women and women not tested for HBsAg during pregnancy, recommendations remain unchanged from the 1999 Recommended Childhood Immunization Schedule. These infants need hepatitis B virus vaccine and hepatitis B immune globulin (HBIG) within 12 hours of birth. At this time the only thimerosal-free hepatitis B vaccine available (COMVAX) also contains Haemophilus influenzae type b (Hib) vaccine (PRP-OMP). This product is not approved for use before 6 weeks of age because of decreased response to the Hib component when administered at this age. For that reason, where available, this thimerosal-free vaccine may be given to infants born to HBsAg-negative women beginning at the 2 month visit. If thimerosal-free vaccine is not available, hepatitis B virus vaccination should be initiated at 6 months of age. Based on the current immunization schedule, for most infants, either of these approaches should allow completion of the necessary three doses of vaccine by 18 months of age. Until thimerosal-free vaccine is available, immunization for the small, prematurely born infant should be deferred until the infant reaches a size and development that corresponds to that of a term infant at birth. Hepatitis B vaccine which does not contain thimerosal is expected to be made available in the near future. When sufficient supplies of this vaccine are available, resumption of the previous recommendation that hepatitis B virus immunization should begin at or soon after birth (0-2 months). Q: What is thimerosal and why is it of concern? A: Thimerosal is an effective preservative that contains mercury. It is the most widely used preservative in vaccines and has been used in some vaccines and other products since the 1930s. Thimerosal prevents bacterial contamination of multi dose vaccine vials when they are opened. Concern has been raised about the very small amount of mercury in some vaccines but no data or evidence indicates any harm caused by the extent of exposure that some infants and children may have encountered in following the routine immunization schedule. Children are not getting toxic quantities of mercury from vaccines. Q: Why is the AAP recommending a temporary delay in the schedule for initiation of hepatitis B virus vaccine, if data are limited regarding the effects of low dose or intermittent exposure to thimerosal in vaccines? A: Exposure to mercury is of concern and, when possible should be avoided. The AAP and the Public Health Service agree that thimerosal should be reduced or eliminated in vaccines to make already safe vaccines even safer, and vaccine manufacturers are working toward this goal. Recent review of FDA guidelines for mercury exposure and the mercury content of vaccines indicate that some children, depending on which vaccines they receive and the timing of those vaccines, may be exposed to cumulative amounts of mercury close to the upper limit of safety ranges of the guidelines. Delaying the hepatitis B virus vaccine further increases the margin of safety. Q: What does the AAP recommend if I have a patient scheduled to receive the second dose of hepatitis B vaccine and the patient has already received their first dose at birth? A: The AAP Committee on Infectious Diseases recommends that the second dose in the series should be delayed until 6 months of age if thimerosal-free vaccine is not available. If the physician has access to the thimerosal-free combination hepatitis B and H. influenzae type b vaccine (COMVAX), the second dose may be provided at 2 months of age. Children who already received one dose of hepatitis B virus vaccine at or shortly after birth may be administered COMVAX at ages 2, 4, and 12-15 months of age. The extra dose of hepatitis B virus vaccine these children would receive is acceptable. Q: Can children who began their hepatitis B immunization series with one of the thimerosal containing products complete the schedule with the thimerosal-free product (COMVAX) at 12-15 months of age? A: Yes, all hepatitis B products are interchangeable as are all Hib products. Q: The AAP recommends that immunization with hepatitis B vaccine for the small, prematurely born infant should be deferred until the infant reaches a size and development that corresponds to that of a term infant. Should the hepatitis B immunization be initiated 6 months from the date of birth or 6 months from the time the infant is considered term? A: Until a thimerosal-free vaccine is available, premature infants whose mothers are HBsAg negative should not receive the vaccination until they are 6 months of age, have reached term gestational age, and weigh at least 2.5 kilograms. Q: The State Health Department is recommending the first dose of hepatitis B vaccine be initiated at 2 months of age and the AAP is encouraging me to initiate the series at 6 months of age. Which schedule should I follow? A: The AAP and the CDC agree that the HBV vaccine should not be given in the first 2 months of life to infants born to HBsAg-negative women, but they differ regarding the time of initiation of the HBV vaccine. The AAP recommends 6 months while the CDC recommends 2 to 6 months. Clinicians and parents can discuss these options Q: The CDC recommends immunization of high-risk populations beginning at birth with hepatitis B vaccine. What does they AAP recommend regarding immunization of high-risk populations? A: The AAP and the CDC differ on the recommendation for immunization of high-risk populations. When the mother is HBsAg-negative at the time of birth, the risk of her infant acquiring hepatitis B during the first year of life is very small irrespective of nationality. The concern of CDC is based on two related points: 1) a significant risk of horizontal transmission exists prior to school entry, and 2) the CDC national immunization surveillance data indicate that if hepatitis B virus vaccination is not started at birth, approximately 10% fewer of these high risk children will be fully vaccinated against hepatitis B virus. Thus, for a pediatrician who considers the family to be reliable, postponing the hepatitis B vaccination series according to these AAP recommendations is reasonable. However, from the public health perspective of the CDC the 10% decrease in immunization rate led to their recommendation to vaccinate infants in high risk groups at birth." Q: Once there are thimerosal-free hepatitis B vaccines available will the AAP and CDC go back to a recommendation for initiation of the vaccine at birth? A: Initiation of the HBV vaccine at birth as is outlined in the 1999 Recommended Childhood Immunization Schedule is an effective way to prevent HBV infections. Both the AAP and the CDC hope that thimerosal-free HBV vaccines will be available in the near future and that the current routine childhood immunization schedule can be resumed. Q: How can parents obtain information about childhood immunizations? A: Please encourage parents to visit both the AAP web site at http://www.aap.org and the CDC web site at http://www.cdc.gov/nip/Q&A/genqa/thimerosal.htm. --------------------------------------------------------------------- >> Rayakan Natal, klik,http://www.indokado.com/christmasflowers.html >> Info balita, http://www.balita-anda.com >> Stop berlangganan, e-mail ke: [EMAIL PROTECTED]
