The following article is reproduced by permission of AAP News, June 2000, Vol. 16, No. 6, p. 1. AAP News is a monthly publication of the American Academy of Pediatrics (AAP). Dr. Pickering is a member of the AAP Committee on Infectious Diseases and editor of the 2000 Red Book.

Resume hep B immunization at birth: AAP
Larry K. Pickering, M.D., FAAP

Evidence shows many U.S. hospitals that discontinued routine hepatitis B vaccination of all newborn infants have not resumed giving the birth dose, despite the Academy's recommendation to do so based on the availability of vaccines that do not contain thimerosal as a preservative.

The purpose of this article is:

• to ensure that clinicians and hospital personnel are aware of the widespread availability of hepatitis B vaccines that do not contain thimerosal as a preservative;
• to underscore the rationale and importance of resuming the routine birth immunization of infants against hepatitis B; and
• to stress the importance of screening pregnant women for their hepatitis B surface antigen (HBsAg) status.

Evidence supporting a policy of universal infant hepatitis B immunization in the United States is compelling. Children infected with hepatitis B virus (HBV) are much more likely to develop chronic HBV infections when compared to the risk for adults (see Table 1).

Approximately one-third of chronic HBV infections in the United States result from perinatal and early childhood infections. Each year, approximately 20,000 women with chronic hepatitis B infection give birth in the United States, and without appropriate immunoprophylaxis, 6,000 infants would become HBV-infected annually. Most of these infections, however, can be prevented by prenatal screening of pregnant women for the presence of HBsAg.

Infants born to mothers who are HBsAg-positive reduce their chances of developing acute perinatally acquired hepatitis B by receiving the first dose of hepatitis B vaccine and hepatitis B immune globulin (HBIG) at separate sites within 12 hours of birth.

Hepatitis B vaccine is very immunogenic when given at birth and confers protection against the most serious complications of HBV infection (chronic cirrhosis and hepatocellular carcinoma) for at least 10 years. Long-term immunologic memory in immunized infants can be expected to protect them against HBV infections when they are adolescents and adults. Universal infant immunization with hepatitis B vaccine is a key component of the overall strategy for eliminating HBV transmission in the United States.

Concerns over thimerosal
In the past year, the success of the strategy of initiating hepatitis B immunization at birth has been interrupted by concerns about the commonly used vaccine preservative thimerosal.

On July 7, 1999, the Academy and the U.S. Public Health Service (USPHS) issued a joint statement suggesting that clinicians and parents could take advantage of the flexibility in the hepatitis B immunization schedule to postpone the first dose of hepatitis B vaccine given to infants born to HBsAg-negative women until 2 to 6 months of age. The joint statement also advised that, due to the substantial risk of infection to infants in the perinatal period, infants born to mothers who are HBsAg-positive or whose HBsAg status is unknown should continue to receive the thimerosal-containing hepatitis B vaccine within 12 hours of birth.

In response to concerns about thimerosal, vaccine manufacturers quickly developed hepatitis B vaccines that do not contain thimerosal as a preservative. In September 1999, an FDA-approved hepatitis B vaccine that does not contain thimerosal as a preservative was released by Merck Vaccine Division (Recombivax HB), and in April 2000 a hepatitis B vaccine that does not contain thimerosal as a preservative became available from SmithKline Beecham Pharmaceuticals (Engerix B). There is now sufficient supply of vaccines that do not contain thimerosal as a preservative to meet the hepatitis B immunization needs of all children in the United States.

Routine birth immunization
Based on the availability of these preservative-free hepatitis B vaccines, the Academy and the USPHS have recommended, "Routine hepatitis B vaccination policies for all newborn infants should be reintroduced immediately in hospitals in which these policies and practices have been discontinued." (MMWR. 1999;48:780-782.)

The Academy has recommended that physicians who had stopped administering the hepatitis B vaccine at birth due to concerns over thimerosal should resume immunization of infants with vaccine that does not contain thimerosal as a preservative "optimally at birth and no later than 2 months of age" (AAP News, November 1999).

There is accumulating evidence, however, that resumption of the birth dose has not occurred in many hospitals throughout the United States. Studies carried out by the Centers for Disease Control and Prevention (CDC) and others indicate that, soon after publication of the AAP-USPHS joint statement, most hospitals discontinued policies and practices for immunizing all newborn infants of HBsAg-negative mothers at birth. An alarming number of hospitals also suspended administration of hepatitis B vaccine to all infants, regardless of the mother's hepatitis B surface antigen status.

Preliminary results of a March 2000 survey of all birthing hospitals in Wisconsin found a reduction of hospitals offering hepatitis B vaccine at birth from 80% before the thimerosal alert to 48% six months after vaccines that do not contain thimerosal as a preservative became available, according to Thomas Saari, M.D., FAAP, professor of pediatrics, Division of Pediatric Infectious Diseases, University of Wisconsin Medical School, Madison, and member of the AAP Committee on Infectious Diseases. Some 30% of Wisconsin hospitals suspended policies for immunizing infants born to HBsAg-positive mothers during the thimerosal alert, and 6% have not yet resumed this recommended practice.

The reintroduction of these policies and practices has been slow despite the availability of hepatitis B vaccines that do not contain thimerosal as a preservative, reports Hussain Yusef, M.D., epidemiologist with the CDC National Immunization Program.

Screening pregnant women for HBsAg status
The vast majority (85% to 95%) of infections transmitted during the perinatal period can be prevented if HBsAg-positive mothers are identified and their infants receive the first dose of hepatitis B vaccine and HBIG within 12 hours of birth. Administering hepatitis B vaccine alone at birth to these infants and completing the three-dose series by 6 months of age is only slightly less effective in preventing HBV infection as is administering both HBIG and hepatitis B vaccine.

To date, only 17 states require screening for HBsAg status for women during pregnancy in the United States. Obstetricians and family practitioners should routinely screen all women for their HBsAg status during each pregnancy, regardless of the presence or absence of risk factors. Fifty percent of women in childbearing years who are asymptomatic carriers of hepatitis B lack risk factors (IV drug use, sexual contact with a known hepatitis B carrier, transfusion recipient, occupational exposure.)

Infants born to HBsAg-positive mothers should complete postexposure immunoprophylaxis and undergo postimmunization testing at 9 months to 15 months of age to confirm the presence of protective hepatitis B antibody. Household and sexual contacts of HBsAg-positive women also should be tested for HBsAg status and receive hepatitis B immunization as indicated.

In summary, the following aspects of hepatitis B virus infection and prevention need to be stressed:

• The risk of infection during early childhood is not confined to children whose mothers are chronically infected with HBV. The substantial number of children infected during childhood are born to women who are not chronically infected but probably result from close contact with household members and caretakers who are acutely or chronically infected.
• Policies should be in place to screen all pregnant women during each pregnancy and to ensure that all infants born to HBsAg-positive women receive timely and appropriate immunoprophylaxis. Initiating hepatitis B immunization at birth has the following advantages:

1. eliminates the possibility of missed immunoprophylaxis in infants born to women who are chronically infected with HBV;
2. ensures that infants born to women whose HBsAg status is unknown at the time of delivery receive timely immunoprophylaxis;
3. reduces the risk of early childhood infection;
4. avoids a missed opportunity for immunization by initiating immunization at the earliest contact between the provider and infant;
5. helps to convey the importance and role of this and other vaccines to the parent and hospital staff;
6. reduces the number of doses that need to be administered simultaneously with other vaccines during subsequent well-child visits; and
7. may increase the likelihood of completion of the three-dose hepatitis B vaccine series. (Lauderdale, et al. JAMA. 1999;282:1725-1730[Medline].)

All hospitals and neonatal care providers should strongly consider initiating, re-instituting or maintaining policies and practices that provide for routine administration of the first dose of hepatitis B vaccine at birth to all infants. Hepatitis B vaccines that do not contain thimerosal as a preservative are now widely available for children of all ages.