AJPH Editorials, January 1999

Surveillance and Prevention of Hepatitis B Virus Transmission

Two articles in this issue of the Journal focus upon hepatitis B virus (HBV) infection, one assessing the prevalence of chronic HBV infection using the National Health and Nutrition Examination Surveys (NHANES)¹ and the other evaluating maternal hepatitis B surface antigen (HBsAg) screening practices.² The 2 studies represent important, though different, activities relevant to monitoring progress in the overall strategy for eliminating HBV infection in the United States. The research conducted by McQuillan and colleagues reviewed population-based trends in seroprevalence of HBV infection, using data from NHANES II (1976­1980) and NHANES III (1988­1994), and identified individual risk factors associated with HBV infection.¹ Barr et al. present results from their study of hospital-based medical record reviews to assess the state-wide hepatitis B surface antigen (HBsAg) screening rate of pregnant women.² Prenatal screening is important to detect infected women so that their newborns receive appropriate post-exposure prophylaxis.

McQuillan et al. suggest that there has not been a significant decrease in HBV infection between the time periods of 1976 to 1980 and 1988 to 1994. While these conclusions may be valid, they fail to provide a context that takes into account the sample size limitations of NHANES, the timing of the surveys, and, most important, the fact that serologic surveys are less valuable for monitoring disease trends than for estimating past and present experience with an infection and its consequences. Because of limited sample sizes, HBV prevalence estimates based upon NHANES data may lack the power to detect small changes over relatively short periods of time. In addition, seroprevalence measures lag behind acute disease surveillance indicators. During the last decade there has been a substantial decrease in the number of reported cases of acute HBV infection. The number of reported clinical HBV cases decreased from a high of 26 611 in 1985 to 10 637 cases in 1996.³

The prevalence and risk of HBV infection varies by age, as well as race and ethnicity, as McQuillan et al. have observed. Similarly, the risk of developing chronic HBV infection varies by age.⁴ Infants born to HBsAg-positive mothers are at increased risk of acquiring HBV infection and of becoming chronically infected unless they receive hepatitis B immune globulin (HBIG) and hepatitis B vaccine beginning at birth. Therefore, one of the key elements of the HBV elimination strategy in the United States is to prevent perinatal HBV transmission. Based on the estimated prevalence of chronic HBV infection among women of reproductive age from NHANES and on state natality data, the Centers for Disease Control and Prevention (CDC) calculates the expected number of births to HBsAg-
positive women in the nation and for each state.^4,5

Without HBsAg screening of pregnant women and appropriate immunoprophylaxis of infants of HBsAg-positive women, CDC estimates that, annually, more than 20 000 infants exposed to HBV at birth would be at risk for chronic HBV infection in the United States.^4,5 Therefore, it is critical that all pregnant women receive HBsAg screening and that infants receive proper treatment at birth and are reported to state or local health departments to ensure completion of the 3-dose series and receipt of post-vaccination testing.^6,7 Health departments may also ensure that HBsAg-positive women receive counseling regarding the need for medical evaluation to assess liver functioning, preventing HBV transmission to sexual or household contacts by, for instance, identifying sexual or household contacts who should be vaccinated, and treating their newborns beginning at birth.

The expected numbers of births serve as benchmarks for national, state, and local perinatal HBV prevention program staffs to evaluate the effectiveness of prevention efforts. Annually between 1993 and 1996, less than 45% of the expected 20 000 births to HBsAg-positive women were identified or reported by state and local immunization programs (CDC, unpublished data, 1998). The reasons for the low number of reported HBsAg-
positive women is not clear at this time but may include failure to identify infected women due to lack of screening for women at greater risk (e.g., women with no prenatal care); underreporting to state and local health departments by prenatal care providers, laboratory personnel or hospital staff; inaccurate state-level estimates of the annual number of births to HBsAg-positive women; or a combination of these three. However, the results of a meta-analysis that CDC is conducting confirm that the state-level estimates are reflective of the actual numbers of births to HBsAg-positive women (CDC, unpublished data, 1998).

All HBsAg-positive pregnant women need to be identified so that their newborns receive HBIG and the first dose of hepatitis B vaccine within 12 hours of birth. While recommendations for universal screening of pregnant women were issued beginning in 1988,^8­11 confusion regarding these recommendations still occurs. For example, the Guidelines for Perinatal Care, recently published by the American Academy of Pediatrics and the American College of Obstetricians and Gynecologists, states that routine prenatal HBsAg screening is indicated only for pregnant women who have not been vaccinated or whose HBsAg status is unknown.¹² However, even vaccinated women should be tested since they may have been infected with HBV prior to vaccination. It is estimated that, nationally, at least 90% of women are being screened for HBsAg prior to or at the time of delivery (CDC, unpublished data, 1998), but women who are not screened during prenatal care have a greater risk of being HBsAg-positive.¹³ Furthermore, an infant born to an HBsAg-positive mother is at risk of not receiving immunoprophylaxis if maternal status is not appropriately documented. While overall screening levels may be high, as Barr et al. observed,² the transfer of maternal HBsAg status from the prenatal care provider to the hospital remains problematic, especially in certain facilities.

To ensure that all HBsAg-positive pregnant women are screened and identified, all birthing facilities should have written clinical policies and administrative procedures to ensure that all pregnant women are screened for HBsAg prior to delivery. If a woman is admitted for delivery without documentation of prior screening, she should be tested at the time of admission for delivery. In addition, policies and procedures should be developed to ensure that all infants born to mothers with unknown HBsAg status are managed appropriately. Laws or regulations to require prenatal HBsAg screening of all pregnant women during each pregnancy and reporting of HBsAg-positive pregnant women to state or local health departments should be considered in all states to ensure compliance with the recommendations.¹⁴

CDC recommends that state or local perinatal HBV prevention programs conduct medical record reviews in major birthing facilities to verify appropriate maternal HBsAg screening and documentation practices. The study by Barr et al. is one such example.² While most previous studies have relied upon health department personnel to conduct the record reviews, Barr et al. demonstrate that hospital personnel can be reliable abstractors. However, as the researchers have noted, it would be beneficial to have a sampling methodology to identify hospitals with deficient screening practices. CDC staff are in the process of developing a standardized method to simplify the record review process by personnel in public health departments as well as hospitals.

In addition to preventing perinatal HBV transmission, the elimination of HBV in the United States also depends upon routine hepatitis B vaccination of infants, adolescents, and high-risk adults.^15,16 Recent data from the National Immunization Survey indicate that 84% of infants aged 19 to 35 months have received 3 or more doses of hepatitis B vaccine.¹⁷ The findings of McQuillan et al.¹ that the prevalence of HBV infection increases after 12 years of age support the current recommendations for universal vaccination of infants and adolescents before they reach ages when they are at greater risk of infection. An estimated 70% of the new HBV infections occur among adolescents and young adults between the ages of 15 and 39 years.³ Disease models have demonstrated that if, in addition to immunization of all infants, 2 million adolescents were immunized each year, a 60% decline in HBV infection would occur within 20 years, compared to a 35% to 45% decline with infant immunization only.¹⁶

While sustaining high infant vaccination coverage levels and increasing routine adolescent vaccination practices, we must also focus on vaccinating those at highest risk of infection to accelerate the elimination of HBV infection. When the vaccine was introduced in 1982, initial strategies focused on vaccinating high risk adults. However, because of the difficulty in reaching high risk individuals, and given that 30% to 40% of individuals acquiring HBV infection do not have identifiable risk factors, the approach met with only limited success.^19,20 Surveillance data indicate that approximately 40% of persons with acute hepatitis B have previously been treated for a sexually transmitted disease (STD).²¹ Clients of STD clinics who are evaluated for a STD should be considered as at high risk for acquiring HBV infection and therefore should be vaccinated against HBV.²² One of the primary barriers to implementing and sustaining hepatitis B vaccination programs for high risk adults, including women who may or may not be pregnant, is funding for the vaccine. While eligible adolescents through 18 years of age may receive hepatitis B vaccine through the Vaccines for Children program,²³ assuring resources to support vaccination of adults remains a challenge.

There is an ongoing need for conducting studies that monitor progress toward the elimination of HBV transmission in the United States and that help to refine prevention strategies. For example, state-wide medical record reviews to assess maternal HBsAg screening practices like that conducted by Barr et al. need to be replicated in other states. Perinatal HBV prevention is unique among vaccination programs since hospitals play a key role. Recognition of this critical role is essential; hospital-based evaluations with productive feedback can help to ensure compliance with screening recommendations. In settings where vaccines are administered, clinic-based assessments should be conducted to ensure that high vaccination coverage levels are achieved. Vaccination coverage assessments, like screening assessments, represent programmatic measures for evaluating progress.

Seroprevalence studies like that of McQuillan et al. provide direct outcome measures of program effectiveness. In addition, they help to identify those at greatest risk of infection and therefore assist in effectively targeting prevention strategies. These efforts are consistent with the Department of Health and Human Service's Initiative to Eliminate Racial and Ethnic Disparities in Health, as well as the Healthy People 2010 objectives currently under development by the same agency. Both efforts call for eliminating racial and ethnic health disparities, including incidence of HBV disease.

 

Nicole Smith, MPH, MPP

Hussain Yusuf, MBBS, MPH

Francisco Averhoff, MD, MPH

National Immunization Program

Centers for Disease Control and Prevention

Atlanta, Ga

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References

1. McQuillan GM, Coleman PJ, Kruszon-Moran D, Moyer LA, Lambert SB, Margolis HS. Prevalence of hepatitis B virus infection in the United States: the National Health and Nutrition Examination Surveys, 1976 through 1994. Am J Public Health. 1999;89:14­18.

2. Barr D, Hershow R, Furner S, Handler A, Levy P. Assessing prenatal hepatitis B screening in Illinois with an inexpensive study design adaptable to other jurisdictions. Am J Public Health. 1999;89:19­24.

3. Centers for Disease Control and Prevention. Summary of notifiable diseases, United States, 1996. MMWR Morb Mortal Wkly Rep. 1997;45:10, 74­79.

4. Margolis HS, Alter MJ, Hadler SC. Hepatitis B: evolving epidemiology and implications for control. Semin Liver Dis. 1991;11:84­92.

5. Centers for Disease Control and Prevention. Hepatitis Surveillance Report. Atlanta, Ga: Centers for Disease Control and Prevention; 1996. No. 56.

6. Centers for Disease Control and Prevention. Prevention of perinatal hepatitis B through enhanced case management: Connecticut, 1994­95, and United States, 1994. MMWR Morb Mortal Wkly Rep. 1996;45:584­587.

7. Kohn MA, Farley TA, Scott C. The need for more aggressive follow-up of children born to hepatitis B surface antigen­positive mothers: lessons from the Louisiana Perinatal Hepatitis B Immunization Program. Pediatr Infect Dis J. 1996;15:535­540.

8. Centers for Disease Control and Prevention. Prevention of perinatal transmission of hepatitis B virus: prenatal screening of all pregnant women for hepatitis B surface antigen. MMWR Morb Mortal Wkly Rep. 1988;37:341­346, 351.

9. Committee on Infectious Diseases. Report of the Committee on Infectious Diseases. 22nd ed. Elk Grove Village, Ill: American Academy of Pediatrics, 1991:238­255.

10. Committee on Obstetrics, Maternal and Fetal Medicine. Guidelines for Hepatitis B Virus Screening and Vaccination During Pregnancy. Washington, DC: American College of Obstetrics and Gynecology; 1990.

11. American Academy of Family Physicians. Recommendations for Hepatitis B Preexposure Vaccination and Postexposure Prophylaxis. Kansas City, Mo: American Academy of Family Physicians; August 1992. Order no. 966.

12. American Academy of Pediatrics and the American College of Obstetricians and Gynecologists. Guidelines for Perinatal Care. 4th ed. Elk Grove Village, Ill: American Academy of Pediatrics; August 1997.

13. Silverman NS, Darby MJ, Ronkin SL, Wapner RJ. Hepatitis B prevention in an unregistered prenatal population. JAMA. 1991;266:2852­2855.

14. Yusuf HR, Mahoney FJ, Shapiro CN, Mast EE, Polish L. Hospital-based evaluation of programs to prevent perinatal hepatitis B virus transmission. Arch Pediatr Adolesc Med. 1996;150:593­597.

15. Centers for Disease Control and Prevention. Hepatitis B virus: a comprehensive strategy for eliminating transmission through universal childhood vaccination. Recommendations of the Immunization Practices Advisory Committee (ACIP). MMWR Morb Mortal Wkly Rep. 1991;40(RR-13):1­20.

16. Centers for Disease Control and Prevention. Update: recommendations to prevent hepatitis B virus transmission--United States. MMWR Morb Mortal Wkly Rep. 1995;44:574­575.

17. Centers for Disease Control and Prevention. National, state and urban area vaccination coverage levels among children aged 19­35 months--United States, 1997. MMWR Morb Mortal Wkly Rep. 1998;47(26):547­554.

18. Margolis HS. Prevention of acute and chronic liver disease through immunization: hepatitis B and beyond. J Infect Dis. 1993;168:9­14.

19. Shapiro CN. Epidemiology of hepatitis B. Pediatr Infect Dis J. 1993;12:433­437.

20. Alter MJ, Hadler SC, Margolis HS, et al. The changing epidemiology of hepatitis B in the United States: need for alternative vaccination strategies. JAMA. 1990;263:1218­1222.

21. Mast EE, Williams IT, Alter MJ, Margolis HS. Hepatitis B vaccination of adolescent and adult high-risk groups in the United States. Vaccine. In press.

22. Centers for Disease Control and Prevention. 1998 guidelines for treatment of sexually transmitted diseases. MMWR Morb Mortal Wkly Rep. 1998;47(RR-1):1­111.

23. Immunization Practices Advisory Committee, Centers for Disease Control and Prevention. Vaccines for Children Program (VFC) Resolution 10/97-1. October 23, 1997.

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