Progress Toward Elimination of Mother-to-Child Transmission of Hepatitis B Virus — Region of the Americas, 2012–2022

Abstract

In 2022, an estimated 5 million persons in the World Health Organization Region of the Americas (AMR) were living with chronic hepatitis B virus (HBV) infection, the leading cause of hepatocellular carcinoma and cirrhosis worldwide. Most chronic infections are acquired through mother-to-child transmission (MTCT) or horizontal transmission during childhood and are preventable with hepatitis B vaccination, including a birth dose (HepB-BD), followed by 2–3 additional doses (HepB3) in infancy. The Pan American Health Organization (PAHO) Elimination of MTCT of HBV infection strategy is intended to reduce chronic HBV infection (measured by hepatitis B surface antigen [HBsAg] seroprevalence) to ≤0.1% among children by achieving 1) ≥95% coverage with HepB-BD and HepB3; and 2) ≥80% of pregnant women received testing for HBsAg, and provision of hepatitis B immunoglobulin to HBV-exposed neonates. By 2012, all 51 AMR countries and territories (countries) provided HepB3 nationwide, and by 2021, 34 (67%) provided HepB-BD nationwide. Mathematical models estimate that HBsAg seroprevalence in children is ≤0.1% in 14 (28%) of 51 countries and at the regional level. Three (6%) of 51 countries met the 95% coverage targets for both HepB3 and HepB-BD during both 2021 and 2022. Of these, two have likely met criteria for the elimination of MTCT of HBV infection. However, in 2022, HepB3 coverage had declined by ≥10 percentage points in 15 (37%) of 41 countries with 2012 coverage data for comparison. These declines in HepB3 coverage, as well as the absence of HepB-BD in the routine immunization schedules in 17 countries, threaten PAHO’s progress toward the elimination of MTCT of HBV infection. Efforts to introduce HepB-BD and maintain high HepB3 and HepB-BD coverage are needed.

Introduction

Globally, chronic hepatitis B virus (HBV) infection is the leading cause of hepatocellular carcinoma and cirrhosis (1). In 2022, an estimated 5 million persons in the World Health Organization (WHO) Region of the Americas (AMR)* had chronic HBV infection, and approximately 20,000 died from hepatitis B–related causes (2). Most chronic HBV infections are acquired through mother-to-child transmission (MTCT) or horizontal transmission during early childhood (1). Infections acquired at age ≤5 years are more likely to become chronic than are those acquired later in life (1). To prevent chronic HBV infection, WHO recommends that all infants receive a timely birth dose of hepatitis B vaccine (HepB-BD), defined as receipt within the first 24 hours of life, with 2–3 additional doses (HepB3) preferably administered during the first months of life, simultaneous with vaccines containing diphtheria, tetanus, and pertussis (1).

In 1999, the Pan American Health Organization (PAHO) recommended that the 51 countries and territories (countries) in AMR provide HepB3 vaccination for all infants nationwide (universal vaccination) and, in 2011, recommended the inclusion of a universal HepB-BD (3,4). In 2017, PAHO expanded its strategy for achieving the elimination of MTCT of HIV and syphilis to include HBV infection and Chagas disease (EMTCT Plus) (5). PAHO’s EMTCT Plus strategy includes the impact target of reducing hepatitis B surface antigen (HBsAg) seroprevalence (a marker for chronic HBV infection) to ≤0.1% among children aged 4–6 years, and several programmatic targets: 1) achieving high coverage (≥95% nationally and >85% in all provinces or areas) with timely HepB-BD and HepB3; and 2) increasing HBsAg testing among pregnant women and provision of hepatitis B immunoglobulin (HBIG) to HBV-exposed neonates to ≥80% (5). The WHO global criteria for the elimination of MTCT of HBV infection are similar and include achieving ≤0.1% HBsAg seroprevalence among children aged ≤5 years^† and ≥90% coverage with timely HepB-BD and HepB3 for the two most recent, consecutive years (6). This report describes progress toward the elimination of MTCT of HBV infection in AMR during 2012–2022 (3,5,6).

Methods

Vaccination Activities

Hepatitis immunization schedules, year of hepatitis vaccine introduction nationwide (universal), and WHO/UNICEF National Immunization Coverage estimates or administrative immunization coverage for timely HepB-BD and HepB3 among children aged <1 year were compiled from PAHO, UNICEF, and WHO immunization data portals, unless otherwise indicated (3). WHO/UNICEF National Immunization Coverage estimates are based upon annual country reports submitted via the WHO/UNICEF Joint Reporting Form on Vaccination and coverage surveys.

HBsAg Seroprevalence

WHO recommends population-based, nationally representative HBsAg serosurveys among children aged ≤5 years to monitor progress toward the elimination of MTCT of HBV infection (6). Examples of representative serosurveys (national or subnational) in children or cohorts born after introduction and widespread use of hepatitis B vaccine in the AMR were identified through a search of literature published after 2016 and were reviewed (3). Mathematical modeling estimates of HBsAg seroprevalence in children published by the Global Burden of Disease Collaborators,^§ The Global Health Observatory,^¶ and the Center for Disease Analysis/Polaris Observatory Collaborators** were reviewed and compiled.

Additional Indicators for EMTCT Plus

Data on the proportion of pregnant women with at least four prenatal care visits and of births at health facilities were compiled from PAHO’s Core Indicator Portal. Data describing the presence of policies for universal testing for HBV in antenatal care and provision of HBIG to HBV-exposed newborns were compiled from published literature and PAHO and country websites describing strategies for hepatitis B control and the elimination of MTCT of HBV infection. This activity was reviewed by CDC, deemed not research, and was conducted consistent with applicable federal law and CDC policy.^††

Results

Vaccination Activities

HepB3. By 2012, all 51 AMR countries provided universal HepB3 vaccination (3) (Table 1). Regional HepB3 coverage increased steadily during the 1990s and ranged from 88% to 91% during 2005–2016 (Figure) (3). Regional coverage declined to 79% in 2019 but rebounded to 83% in 2022.

HepB3 coverage in 2022 declined by ≥13 percentage points from that in 2012 in the Andean Area, Central America, and Southern Cone and Brazil subregions (Table 1) and declined by ≥10 percentage points in 15 (37%) of 41 countries reporting data for both 2012 and 2022 (3). Coverage in Haiti and Suriname never exceeded 68% and 81%, respectively, during the reporting period. Twelve countries met the global target of ≥90% HepB3 coverage during both 2021 and 2022; among those, five met the PAHO target of ≥95% coverage.

HepB-BD. As of 2021, 34 (67%) countries provided universal HepB-BD vaccination (Table 1) (3). During 2000–2022, regional HepB-BD coverage increased from 23% to 65% (Figure) (3) and during 2012–2022, remained relatively stable or increased in all subregions. Among 15 countries reporting HepB-BD coverage for 2012 and 2022, coverage declined in 2022 by ≥10 percentage points in Argentina, Costa Rica, Mexico, and Venezuela compared with that in 2012 (3). Seven countries met the global target of ≥90% HepB-BD coverage during both 2021 and 2022; among those countries, five met the PAHO target of ≥95% coverage.

HBsAg Seroprevalence

Estimates from three mathematical models suggest that regional HBsAg seroprevalence among children aged ≤5 years is <0.1% (Table 2). Among 26 countries for which three modeled estimates are available, the estimated seroprevalence from all three models is ≤0.1% in 14 (54%) countries, among which two (Chile and Cuba) reported both HepB3 and HepB-BD coverage ≥95% during both 2021 and 2022. Recently published nationally representative HBsAg serosurveys that included children and vaccine-eligible cohorts conducted in Haiti, Mexico, and the United States corroborate the 2022 estimates for these countries. In addition, recently published HBsAg serosurvey results from population-based subnational surveys conducted in AMR show that decades of vaccination against HBV have led to reductions in the seroprevalence of HBsAg among cohorts that have been age-eligible for vaccination compared with seroprevalence among older cohorts.

Additional Indicators for EMTCT Plus

According to reports received by PAHO from 35 countries, as of 2020, 19 (54%) had national goals for the elimination of MTCT of HBV infection (5). Forty-three countries reported data on prenatal care visits by pregnant women; in 21 (49%) countries, ≥90% of pregnant women had at least four prenatal visits. In 27 of 30 (90%) countries with data on delivery location, ≥91.5% of births were at health facilities. Twenty-seven (84%) of 32 countries with data reported providing universal antenatal HBV testing, and 24 (75%) of 32 reported providing HBIG for neonates born to mothers with high levels of HBV DNA; however, the extent of coverage with these interventions is unknown in many AMR countries.

Discussion

Substantial progress has been made toward the elimination of MTCT of HBV infection in AMR. PAHO has supported vaccination against hepatitis B in the region since the 1990s by 1) advocating for vaccination to stakeholders, 2) providing technical support for the development of national vaccination policies, 3) building health care worker capacity, and 4) facilitating vaccine procurement.^§§ Mathematical models estimate the prevalence of chronic HBV infection among children aged ≤5 years, as measured by HBsAg seroprevalence, to be <0.1% regionally, and 14 countries met both regional and global impact targets for the elimination of MTCT of HBV infection (5,6). Among the 14 countries identified as likely to have met the HBsAg seroprevalence target, two reported HepB-BD and HepB3 coverage ≥95% during both 2021 and 2022, meeting both the regional and global programmatic targets for the elimination of MTCT of HBV infection, and both implemented antenatal and maternal and child health policies supporting the elimination of MTCT of HBV infection (5,6).

PAHO has endorsed a process for validating achievement of the elimination of MTCT of HBV infection (6), and regional and national validation committees have been established. Because countries are evaluated for the elimination of MTCT of HBV infection, representative seroprevalence data documenting the prevalence of chronic HBV infection in children are needed. Innovative approaches, such as the integration of HBsAg testing into other surveys or sampling focused on geographic areas with documented high risk for HBV infection such as the two-phase method for verifying the elimination of MTCT of HBV infection used in Colombia (7), might facilitate the collection of essential data.

Despite regional progress, an estimated 34,000 children aged ≤5 years in the Americas had chronic HBV infection in 2022 (8). Few countries are consistently achieving the ≥90% HepB3 global coverage target. Declines in HepB3 coverage during 2012–2022 threaten progress toward elimination of chronic HBV infection in children. These declines have been attributed to inadequate sustainable financing and reductions in social mobilization for vaccination, increasing vaccination hesitancy, insecurity linked to civil unrest, lack of easy access to health services for some populations, and recently, the COVID-19 pandemic and consequent health service disruptions^¶¶,***^{,†††,§§§,¶¶¶} (9,10). To overcome these constraints and improve HepB3 vaccination coverage, PAHO is working with countries to implement the recommendations in the 2021 Reinvigorating Immunization as a Public Good for Universal Health resolution**** and the new Regional Immunization Action Plan 2030.^††††

Although most children born in AMR live in countries with routine HepB-BD, 17 countries, particularly in the Caribbean and Latin Caribbean subregions (13 of the 17), have not introduced universal birth dose vaccination (3). In countries with HepB-BD, efforts to address disparities in coverage and access and to ensure timely administration will protect infants at risk for HBV infection (1). Most births in the region occur at health facilities; thus, implementation of policies such as standing orders for newborn HepB-BD vaccination before discharge of mother and child, paired with education of pregnant women and maternal and child health care staff members about the importance of the birth dose, can improve timely administration and coverage.

The region continues to expand efforts to achieve the elimination of MTCT of HBV infection by integrating antenatal viral testing, antiviral treatment during pregnancy when indicated, and provision of HBIG for HBV-exposed newborns into the established platforms providing interventions for the elimination of MTCT of HIV and syphilis (5). PAHO’s Strategic Fund is tasked with improving access to and reducing costs of hepatitis B–relevant health supplies and medicines for the region.^§§§§

Limitations

The findings in this report are subject to at least two limitations. First, current HepB-BD and HepB3 vaccination schedules and coverage or the elimination of MTCT programmatic indicators were not available for all countries or all years, limiting the completeness of summaries on regional progress on the elimination of MTCT of HBV infection. Second, not all countries have systems that differentiate reporting of timely versus any HepB-BD administration, thus potentially overestimating timely birth dose coverage.

Implications for Public Health Practice

Although progress has been made, declines in HepB3 coverage and the absence of HepB-BD introduction in 17 countries threaten PAHO’s progress toward the elimination of MTCT of HBV infection. To advance toward the regional goal of the elimination of MTCT of HBV infection, continued efforts are needed to support HepB-BD introduction and the achievement and maintenance of high HepB-BD and HepB3 coverage.