Progress Toward the Elimination of Mother-to-Child Transmission of Hepatitis B Virus — Worldwide, 2016–2021

Immunization Activities

Because immunization is a key intervention to prevent MTCT of HBV, WHO recommends that all newborns receive a timely HepB-BD^† dose followed by 2–3 additional HepB doses, according to national schedules (1). Countries report immunization data to WHO annually through the WHO and UNICEF Joint Reporting Form. WHO and UNICEF review reported coverage data and surveys to generate country-specific coverage estimates.^§ This activity was reviewed by CDC and was conducted consistent with applicable federal law and CDC policy.^¶

By 2020, 190 (98%) of 194 countries had introduced universal infant hepatitis B vaccination compared with 186 (96%) in 2016. In 2020, 110 (57%) countries provided HepB-BD** to all newborns, a 10% increase from 100 (52%) in 2016. During 2016–2020, 33 to 34 (17%–18%) countries, mostly in the European Region, administered HepB-BD selectively to newborns of HBsAg-positive mothers (i.e., selective or targeted birth dose vaccination) each year.^†† The number of countries that had not introduced routine HepB-BD vaccination declined by 15%, from 60 (31%) in 2016 to 51 (26%) in 2020^§§ (Table 1). Most of these countries are in the African Region where 34 (72%) of 47 countries do not provide a HepB-BD.

During 2016–2020, global coverage with HepB3 remained between 82% and 85%, whereas timely coverage with HepB-BD increased from 37% to 43%. During this period, regional HepB3 and HepB-BD coverages were highest in the Western Pacific Region and lowest in the African Region (Table 1). During 2016–2019, HepB3 coverage was ≥90% in 61%–63% of reporting countries; this proportion declined to 52% in 2020. HepB-BD coverage was ≥90% in 51%–58% of reporting countries, with the highest proportion (58%) observed in 2016 and lowest (51%) in 2017. During 2016–2019, among countries that reported coverage with HepB3 and HepB-BD, 47%–54% reported ≥90% coverage for both; this proportion declined to 41% in 2020 (Table 1).

Other Interventions to Prevent Mother-to-Child Transmission

To prevent MTCT of HBV, countries with selective HepB-BD vaccination policies rely on antenatal screening combined with antiviral treatment for eligible HBsAg-positive pregnant women and postexposure prophylaxis for HBV-exposed infants^¶¶ (1). Information on the performance of these interventions is usually not reportable and is collected through special studies.

In 2020, among 33 countries with selective HepB-BD vaccination policies, 32 (97%) implemented nationwide antenatal hepatitis B screening, with ≥90% coverage in 17 (89%) of 19 countries with available information. HepB-BD coverage among infants born to HBV-infected mothers was ≥90% in all nine countries with available information (6–8).

HBsAg Seroprevalence in Children and Mother-to-Child Transmission Rate

For countries with a universal HepB-BD vaccination policy, the impact target to achieve elimination of MTCT of HBV is ≤0.1% HBsAg prevalence among children aged ≤5 years; for countries with a selective HepB-BD policy, the impact target also includes an MTCT rate ≤2% (Table 2) (4,5). In 2019, WHO estimated global HBsAg prevalence among children aged ≤5 years to be 0.9%, with prevalence ranging from 0.1% in the Region of the Americas to 2.5% in the African region (Table 3) (2). According to a modeling study, HBsAg prevalence among children aged 5 years in 2016 was ≤0.1% in 52 of 119 countries assessed (9); by December 2021, 11 countries*** had demonstrated HBsAg prevalence ≤0.1% in representative serosurveys. Studies in two countries^††† with selective HepB-BD demonstrated an MTCT rate ≤2% (Table 3).

Validation

The Global Validation Advisory Committee for elimination of MTCT of HIV and syphilis was established in 2015. In 2021, the Committee’s role was expanded to include validation of elimination of MTCT of HBV. WHO revised the global guidance on the validation of elimination of MTCT to include “triple” elimination of HIV, syphilis, and hepatitis B (5). The programmatic and impact indicators for validation of elimination of MTCT of HBV vary according to countries’ HepB vaccination programs (Table 2).

Piloting of validation instruments in seven countries^§§§ demonstrated feasibility of their use. Representative serosurvey data to support direct impact measurement were available in five countries.^¶¶¶ In England (the pilot did not include the rest of the United Kingdom), HBsAg prevalence and the MTCT rate were extrapolated from routinely collected antenatal screening data. National HepB immunization coverage data were available in all seven pilot countries; subnational data were available in five.****

Discussion

Substantial progress has been made toward elimination of MTCT of HBV in most WHO regions. Globally, 41 countries reported ≥90% coverage with both HepB-BD and HepB3, a critical component of elimination of viral hepatitis as a public health problem by 2030. Successful implementation of HepB vaccination and other interventions to prevent MTCT globally resulted in a substantial decrease in HBV prevalence among children in all regions except for the African region (2).

Currently, nearly all countries include HepB in their routine infant immunization schedules; however, during 2016–2020, little change in global coverage for HepB3 and HepB-BD was observed. The introduction of HepB-BD into routine immunization programs in 10 additional countries during 2016–2020 is encouraging. However, the slow increase in the number of countries that include HepB-BD in their routine immunization programs suggests that this process has stalled, especially in the African Region. Further, service disruptions caused by the COVID-19 pandemic contributed to the decline of the immunization coverage with HepB in 2020, particularly for HepB3 (10). To meet programmatic targets for elimination of MTCT of HBV, interventions to mitigate the pandemic’s impact on immunization systems need to be implemented (10).

Accelerating the introduction of HepB-BD into the routine immunization programs of remaining countries is essential for achieving global elimination of MTCT of HBV. The African region, which has a high prevalence of chronic HBV infection (2) and where HepB-BD introduction is lagging, requires special attention. Increasing demand among pregnant women and awareness among policymakers and health care workers, improving links between maternal and child health and immunization programs, and ensuring sustainable support would help with successful implementation of HepB-BD vaccination.

Data on impact measures to support validation of elimination of MTCT of HBV are currently available for only a few countries. Countries that have met immunization coverage targets are encouraged to conduct serosurveys to document HBsAg prevalence. Implementing nationwide hepatitis B serosurveys is challenging, given a large sample size and considerable resource requirements. Integration with other serosurveys^†††† or use of multiphase methodology surveys^§§§§ could help reduce implementation costs. Although mathematical modeling is not a substitute for serosurveys, triangulation of various data sources could be considered in assessing the elimination of MTCT of HBV.

To better assess progress toward meeting the elimination targets, countries with selective HepB-BD will need to establish data systems to document performance measures of additional interventions to prevent MTCT of HBV^¶¶¶¶ (4,5). Most HBsAg-positive mothers in countries with historically low HBV prevalence come from countries where prevalence is high (6); therefore, ensuring equal access for foreign-born women to antenatal services and MTCT prevention interventions is important.

The findings in this report are subject to at least two limitations. First, missing immunization data from some countries that did not report to WHO prevent accurate assessment of global and regional coverage. Second, in countries with selective HepB-BD vaccination, limited data availability hampers evaluation of their progress toward elimination of MTCT.

Elimination of MTCT of HBV is achievable with the currently available tools; based on modeled estimates, Elimination of MTCT might have already been attained in several countries (9). Countries will be able to apply for validation once the standardized tools are finalized. For countries with a high prevalence of HBV that do not yet have the capability to achieve impact targets, milestones known as the Path to Elimination which assess progress toward achieving programmatic targets (5) are available to measure progress toward elimination of MTCT. Integration of activities to prevent MTCT of HBV with interventions to prevent MTCT of HIV and syphilis provides the opportunity to synergize across these programs to help achieve triple elimination. Once achieved globally, elimination of MTCT of HBV will result in removing perinatal transmission as a source of chronic HBV infections and will be an important milestone toward achieving elimination of viral hepatitis as a public health threat.