Impact of the 1999 AAP/USPHS Joint Statement on Thimerosal in Vaccines on Infant Hepatitis B Vaccination Practices

On July 8,1999, the American Academy of Pediatrics (AAP) and the U.S. Public Health Service (PHS) jointly recommended reducing infant exposure to thimerosal, a commonly used vaccine preservative that contains mercury (1,2). Specific recommendations were made to postpone the first hepatitis B vaccine dose until 2--6 months of age for infants born to hepatitis B surface antigen (HBsAg)-negative (i.e., not hepatitis B virus [HBV]-infected) women (1,2). Infants born to HBsAg-positive (i.e., HBV-infected) women, or to women whose HBsAg status was unknown, were recommended to receive postexposure prophylaxis with the first dose of hepatitis B vaccine administered within 12 hours of birth (1,2). By mid-September 1999, when adequate supplies of preservative-free hepatitis B vaccine became available, PHS advocated a return to previous infant hepatitis B vaccination practices, including administering the first dose of hepatitis B vaccine to newborns in hospitals that had discontinued the practice (3). In 2000, preliminary assessments of the impact of these policy changes on routine hepatitis B vaccination practices were conducted by public health officials in Wisconsin, Oklahoma, Oregon, and Michigan. This report summarizes the results of these analyses, which indicate that many hospitals in Wisconsin have not reinstated policies to ensure routine administration of hepatitis B vaccine to newborns despite the availability of preservative-free hepatitis B vaccine, that the number of hepatitis B vaccine doses given to newborns in Oklahoma and Oregon has declined, and that an unvaccinated Michigan infant died from fulminant hepatitis B. Restoring routine newborn hepatitis B vaccination practices may require active advocacy by professional and government groups.

In Wisconsin in February 2000, the Division of Public Health mailed a survey to nurse managers of all Wisconsin birthing hospitals to assess the impact of the thimerosal statements on hepatitis B vaccination practices for newborns. Information was collected for the following periods: 1) before July 1999, 2) July--November 1999, and 3) March 2000. In Oklahoma and Oregon, data collected by previously established vaccination registries were used to assess the number of doses of hepatitis B vaccine administered to newborns before and after the publication of the thimerosal statements and after preservative-free hepatitis B vaccine became available. In Michigan, an infant death attributed to HBV was reported in January 2000, and an investigation by the Michigan Department of Community Health (MDCH) included a review of hospital and provider medical records and hospital vaccination policy changes in 1999.

Wisconsin, 1999--2000

All 110 birthing hospitals responded to the survey; 12 no longer provided obstetric services. The percentage of hospitals with written policies or standing orders for routine hepatitis B vaccination of all newborns declined from 81% before July 1999 to 10% during July--December 1999; 77% had policies or orders for routine vaccination of infants born to HBsAg-positive women during July--November 1999.

The proportion of births in hospitals where routine hepatitis B vaccination was given before discharge declined from 84% before July 1999 to 43% in March 2000. Before July 1999, 18 of 20 hospitals in southeastern Wisconsin, where 36% of HBsAg-positive pregnant women in the state resided during 1999, had written policies or standing orders to routinely provide hepatitis B vaccine to newborns. As of March 2000, five of these 18 hospitals had continued or resumed routine administration of hepatitis B vaccine to all newborns.

Oklahoma and Oregon, 1999--2000

In Oklahoma and Oregon, the number of doses administered to newborns and young infants declined in July 1999 (Figure 1). In both states, the number of doses administered to newborns and young infants has not returned to pre-July 1999 levels. Among Oklahoma infants aged <1 month and Oregon infants aged <5 days, the number of hepatitis B vaccine doses administered during May--June 2000 declined 50% and 28%, respectively, compared with May--June 1999.

Michigan, 1999

On December 14, 1999, a previously healthy 3-month-old infant was admitted to a hospital with diarrhea and jaundice, and acute hepatic failure attributed to HBV infection was diagnosed. The infant died on December 17, 1999. The infant had not received her first dose of hepatitis B vaccine until age 2.5 months.

The infant's mother was found to be HBsAg-positive at the first of 10 prenatal visits. However, the prenatal-care record provided to the birth hospital indicated that the mother was hepatitis-negative. Neither the provider nor the laboratory reported the mother's test results to MDCH as required by law. Before July 1999, the birth hospital had routinely administered hepatitis B vaccine series to newborns before discharge but had discontinued this practice in July 1999 because of concerns about thimerosal.

Reported by: N Fasano, MA, J Blostein, MPH, Michigan Dept of Community Health. TN Saari, MD, Univ of Wisconsin, Madison; MB Hurie, MS, JP Davis, MD, Bur of Communicable Disease, Wisconsin Div of Public Health. S Dooley, ARNP, ED Rhoades, MD, Maternal and Child Health Svcs; D Blose, MA, Immunization Div, Oklahoma State Dept of Health. H Gillette, MPH, B Canavan, MPH, Immunization Program, Health Div, Oregon Dept of Human Svcs. Health Svcs Research and Evaluation Br and Program Operations Br, Div of Immunization Svcs, National Immunization Program and Hepatitis Br, Div of Viral and Rickettsial Diseases, National Center for Infectious Diseases, CDC.

Editorial Note: 

The findings in this report indicate that the 1999 statements on thimerosal led to rapid changes in routine perinatal HBV infection prevention practices. Prevention of perinatal and early childhood infection by providing hepatitis B vaccine to newborns is a cornerstone of hepatitis B prevention strategies (4). An estimated 18,000 children aged <10 years were infected with HBV each year before universal infant hepatitis B vaccination was implemented in the United States (CDC, unpublished data, 2000). Approximately half acquired infection through perinatal transmission; the remainder acquired infection during early childhood through contact with other HBsAg-positive persons (horizontal transmission). HBV infection during infancy and childhood carries a higher risk for chronic HBV infection compared with infection during adulthood (5,6). Early hepatitis B vaccination is a safe and effective way to reduce the risk for both perinatal and horizontal HBV transmission and increases the likelihood of children completing the vaccine series on schedule (7,8).

The reported case of acute liver failure from perinatal HBV infection in Michigan underscores the problems associated with discontinuing routine hepatitis B vaccination at birth without being certain that appropriate safeguards against perinatal infection are in place. Hepatitis B vaccine administered alone is 70%--95% effective in preventing perinatal HBV infection when the first dose is given within 24 hours of birth (4). Results from the Wisconsin survey are consistent with results from a national survey of 1000 birthing hospitals conducted during December 1999, 3 months after thimerosal-free vaccine became widely available for infants. In this national survey, the percentage of hospitals with written policies or standing orders for routine hepatitis B vaccination of newborns born to HBsAg-negative women declined from 85% before the 1999 thimerosal statement to 34% in December 1999 (S.J. Clark, University of Michigan, personal communication, 2000). Of 88 hospitals that had discontinued written policies or standing orders for routine vaccination of newborn infants, including infants born to HBsAg-positive women, 67% had not reinstated the policies or standing orders (S.J. Clark, University of Michigan, personal communication, 2000).

It is unknown whether changes in hospital policies and reductions in hepatitis B vaccination coverage of newborns are causing other missed opportunities for vaccination among infants at high risk for perinatal infection, especially among those born to unscreened and HBsAg-positive women. The impact of the public and private health-care system response to concerns about thimerosal may not be understood fully until ongoing analysis of surveillance data and birthing hospital chart reviews provide a more complete assessment of the number of infants who acquired chronic HBV infection as the result of missed vaccination opportunities. CDC is supporting such studies in several states.

AAP and PHS advocate the reintroduction of routine hepatitis B vaccination policies for all newborn infants born in hospitals in which this practice was discontinued because of concerns about thimerosal (3,8). After administering a dose at birth, providers may complete the series with either 2 more doses of single antigen hepatitis B vaccine or with 3 doses of combination Haemophilus influenzae type b/hepatitis B vaccine according to previously recommended schedules (9). All birthing hospitals should have hepatitis B vaccine available for use in infants born to HBsAg-positive and unscreened women. Hospitals should continue to vaccinate all infants at birth until procedures are in place to guarantee that 1) the HBsAg status of every pregnant woman is available and reviewed at delivery, 2) appropriate passive-active immunoprophylaxis (HBIG and hepatitis B vaccine) is provided for infants of HBsAg-positive women within 12 hours of birth, and 3) appropriate active immunoprophylaxis (hepatitis B vaccine) is provided for infants of women with an unknown HBsAg status. Pregnant women who are identified as HBsAg-positive should be reported to local or state health departments to ensure that their infants, family, and household contacts receive a full hepatitis B vaccination series.

Vaccination practices are influenced substantially by recommendations of professional and government advisory groups. The 1999 joint statement and the subsequent AAP guidelines were issued as a precautionary measure and were intended to apply only to infants born to HBsAg-negative women. The inadvertent effect in many hospitals was a persisting change in policies for administering hepatitis B vaccine to infants, most importantly to infants born to HBsAg-positive and unscreened women for whom no changes in vaccination practices had been recommended. Changes in established recommendations, especially if they occur without timely communication and education of health-care providers, may result in misinterpretation and unanticipated changes in vaccination practices.

References

1. CDC. Thimerosal in vaccines: a joint statement of the American Academy of Pediatrics and the Public Health Service. MMWR 1999;48:563--5.
2. American Academy of Pediatrics. Thimerosal in vaccines: an interim report to clinicians. AAP News 1999;15:10--2.
3. CDC. Availability of hepatitis B vaccine that does not contain thimerosal as a preservative. MMWR 1999;48:780--2.
4. Advisory Committee on Immunization Practices. Hepatitis B virus: a comprehensive strategy for eliminating transmission in the United States through universal childhood vaccination. MMWR 1991;40(no. RR-13).
5. Beasley RP, Hwang L-Y. Epidemiology of hepatocellular carcinoma. In: Vyas GN, Diestag JL, Hoofnagle JH, eds. Viral hepatitis and liver disease. New York: Grune & Stratton, 1984:209--24.
6. Margolis HS, Alter MJ, Hadler SC. Hepatitis B: evolving epidemiology and implications for control. Semin Liver Dis 1991;11:84--92.
7. Yusuf HR, Daniels D, Smith P, Coronado V, Rodewald L. Association between administration of hepatitis B vaccine at birth and completion of the hepatitis B and 4:3:1:3 vaccine series. JAMA 2000;284:978.
8. Pickering LK. Resume the hep B immunization at birth: AAP. AAP News 2000;16:1,7.
9. Atkinson W, Humiston S, Wolfe C, Nelson R, eds. Hepatitis B. In: Epidemiology and prevention of vaccine-preventable diseases. 5th ed. Atlanta, Georgia: US Department of Health and Human Services, CDC, 1999.

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