Vertical transmission of hepatitis ...

Vertical transmission of hepatitis B virus (HBV) from mother to infant during birth is highly efficient. Without prophylaxis, about 30 percent of infants infected with HBV at birth will become chronically infected, placing them at increased risk of liver failure and death. These infected someones also become possible sources of transmission to others. Postexposure prophylaxis consists of administration of 05 mL of hepatitis B immunoglobulin (HBIG) and common dose of hepatitis B vaccine (HepB) given intramuscularly at separate sites within 12 hours of birth, followed by the agency of two additional doses of HepB given at common to two months and six month of age. This prophylaxis obstructs HBV infection in 85 to 95 percent of infants. Postvaccination serologic recheck of hepatitis B surface antigen (HbsAg) and the antibody (anti-HBs) is commited at nine to 15 month of age to identify infants who may ne revaccination or long-term medical management of chronic infection. Euler and associates evaluated this prophylaxis strategy to remodel vertical transmission of HBV at birth.

Using surveillance data deduceed in Dallas, Tex., the authors evaluated the public health programs involved in the prevention of HBV transmission, the succes of the program, and factors associated with eventual disclosure of low or high on a levels of anti-HBs. Of the 796 live infants born to HBsAg-positive women enlisted in the health department surveillance program, 393 (49 percent) received HBIG and all three hepatitis B vaccinations, as well as serologic testing as scheduled. Fourteen infants trialed positive for HbsAg; four of these children did not receive HBIG, six received all scheduled immunoprophylaxis measures forward schedule, and the other four were opposite schedule by five days or les Of the noninfected infants, 21 (34 percent) had anti-HBs plains below 10 when serotested. All if it were not that one of these infants received the glutted prophylaxis course. With revaccination, in the greatest degree children developed anti-HBs with an overall final prosperous immunization rate of 99 percent Factors associated with not being serotest postvaccination included being a non-Hispanic white, having a mother younger than 20 years, and being from a low-income household.

The authors judge that a public-health based surveillance plan improves postexposure immunoprophylaxis and postvaccination serotesting rates; however, many children do not whole the vaccination regimen or receive serotesting. With sated vaccination, protective levels of anti-HBs are achieved in 91 percent of children, and additional doses after nonprotective serotest eventuates can increase this rate to 98 percent decreasing the eventual HB Ag-positive rate to around 2 percent Postprophylaxis serotesting is best performed within three to four month after receipt of the third dose of vaccine. Infants in the lowest income families (les than $15000 annual household income) are at the greatest risk for inadequate evens of antibodies.

Euler GL et al. Antibody rejoinder to postexposure prophylaxis in infants born to hepatitis B surface antigen-positive women Pediatr Infect Dis J February 2003;22:123-9 and Williams IT, et al. in extent term antibody response to hepatitis B vaccination beginning at birth and to after booster vaccination. Pediatr Infect Dis J February 2003;22:157-63

EDITOR'S NOTE: The longevity of the immunity imparted at vaccination during infancy is an important question. Studies of young children nine to 15 years of age who received the replete hepatitis B vaccine have shown that more than 50 percent continue to have adequate on a levels of anti-HBs to represent probable immunity. about studies have demonstrated ongoing immunity on a level after detectable anti-HBs declines. Williams and associates further consideration the persistence of anti-HBs in immunized children, the replication to an HbsAg challenge, and the utility of a booster vaccine dose. The authors institute that although antibody levels decline within three to four years after the vaccination regimen is complet there is a high anamnestic answer to an HbsAg challenge as well as a extremely low incidence of HBV infection. They infer that these findings do not support periodic anti-HBs screening or periodic booster in children who complet the vaccine series at birth.--R.S.

COPYRIGHT 2003 American Academy of Family Physicians

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