Assessment of the anti-HBs antibody response in Beninese infants following 4 doses of HBV vaccine, including administration at birth, compared to the standard 3 doses regime; a cross-sectional survey

Towards contextualized complex systems approaches to scaling-up hepatitis B birth-dose vaccination in the African region: a qualitative systematic review

Background

Despite the longstanding implementation of universal hepatitis B infant vaccination programs, the World Health Organization African region (WHO AFRO) maintains the highest prevalence (2.5%) of chronic hepatitis B virus (HBV) infection among children ≤5 years of age. Scaling-up hepatitis B birth-dose (HepB BD) vaccination could avert mother-to-child transmission of HBV infection and advance regional progress towards eliminating viral hepatitis.

Objective

To describe whether - and how - complexities within the health system or intervention influence the performance of HepB BD vaccination programs in the WHO AFRO.

Methods

Using a complexity perspective, we conducted a qualitative systematic review of literature published between 2009-2022. A Boolean search strategy retrieved relevant literature indexed in PubMed, EBSCOhost databases, Scopus, and Web of Science, with supplementary searches conducted to identify any missed articles. No language restrictions were applied. Data extraction, synthesis and analysis were guided by a systems-based logic model tailored to systematic reviews of complex interventions.

Results

Our search yielded 672 published records. Of these, 28 (26 English, 2 French) were eligible for inclusion. Among the 12 WHO AFRO member states represented, the origin of evidence weighted highest in Nigeria (n = 12) and Senegal (n = 5). The performance of HepB BD vaccination programs across member states are influenced by underlying complexities across eight cross-cutting themes: (i) availability and interpretation of HepB BD vaccination policies, (ii) capacity of vaccine supply and cold chain systems, (iii) availability of equitable and sustainable financing, (iv) capacity and capability of health care workers (HCWs), (v) immunization monitoring systems and impaired feedback loops, (vi) influence of context vs system design on the timeliness of vaccination, (vii) maternal knowledge and socio-economic factors, and (viii) wider contextual factors (geography, climate, cultural practices).

Conclusion

Countries looking to introduce, or scale-up HepB BD vaccination programs will benefit from careful consideration of components of the intervention design that are dependent on the end-user's context and capabilities in accessing the vaccine; the adherence and interpretation of essential components of the policy; the provision of adequate support of stakeholders specifically HCWs and government ministries; and the need for innovative approaches to underlying complexities. Lessons offered by these African experiences provide pragmatic approaches to successfully implementing HepB BD vaccination programs in the region.

Immune response to hepatitis B vaccine among children under 5 years in Africa: a meta-analysis

BACKGROUND

Hepatitis B virus (HBV) infection in Africa is mostly acquired before the age of 5 years through vertical or horizontal routes. While all the countries in the World Health Organization African region have introduced HBV vaccination into their national immunization programs, the rate of protective immune response to HBV vaccine among children in Africa has not been systematically synthesized. In this study, we estimated the HBV vaccine seroprotection rate (defined as anti-HBs titer ≥ 10 IU/L) and the associated factors among under-five children who completed a primary series of HBV vaccination in Africa.

METHODS

We systematically searched PubMed, Web Science, and Scopus databases from inception to May 2022 for potentially eligible studies. The pooled seroprotection rate was estimated using a random-effects model with Freeman-Tukey double arcsine transformation and the associated factors were examined using odds ratio estimated by the DerSimonian and Laird method.

RESULTS

From the 1063 records identified, 29 studies with a total sample size of 9167 under-five children were included in the meta-analysis. The pooled seroprotection rate was 89.23% (95% CI   85.68-92.33%, I2 = 95.96%, p < 0.001). In the subgroup analyses, there was a significant difference in the rate by the assay method, vaccine dose, and vaccine combination. HIV-positive children had lower odds of achieving seroprotection when compared with HIV-negative children (OR = 0.22, 95%CI   0.12-0.40).

CONCLUSIONS

The majority of under-five children in Africa achieved seroprotection after completing three or four doses of HBV vaccine. However, the rate was lower among children living with HIV. This calls for interventions to timely identify and address nonresponse to HBV vaccine, particularly among immunosuppressed children.

Risk of early horizontal transmission of hepatitis B virus in children of uninfected mothers in sub-Saharan Africa: a systematic review and meta-analysis

BACKGROUND

Sub-Saharan Africa is highly endemic for hepatitis B virus (HBV); historically, most people were exposed during childhood through vertical or horizontal transmission. Although all African countries now provide a three-dose infant hepatitis B vaccination starting at age 6-8 weeks, only a third of African countries have introduced birth dose (HepB-BD) vaccine. Adding HepB-BD is fundamental to prevent vertical transmission, but its effectiveness in preventing horizontal transmission, compared with the three-dose infant vaccination alone, is unknown. We aimed to estimate the risk of early horizontal transmission in children of hepatitis B surface antigen (HBsAg)-negative mothers in sub-Saharan Africa stratified according to the vaccination schedule.

METHODS

In this systematic review and meta-analysis we searched MEDLINE, Global Health, Embase, African Index Medicus and African Journals Online from their inception to Oct 24, 2022, for studies reporting HBsAg or HBV DNA, or both, in children (aged 0-5 years) of HBsAg-negative mothers. We excluded studies if children were only tested at birth. Two reviewers independently screened the titles and abstracts of all articles and data were extracted using a standardised pre-piloted data extraction sheet, and authors were contacted if any important information was missing. The primary outcome was the risk of HBV infection in children of HBsAg-negative mothers, stratified by vaccination schedule (no vaccination, first dose at 6-8 weeks, or first dose at birth). We pooled the child risks of HBsAg or HBV DNA-positivity from the age of 0 years to 5 years via a random-effect meta-analysis using a generalised linear mixed model. The study was registered on PROSPERO, CRD42021236203.

FINDINGS

Of 8856 articles identified, 27 studies evaluating 10 003 children of HBsAg-negative mothers were included. The pooled risks of infection were 6·16% (95% CI 3·05-12·04; 155/1407) in the no vaccination group, 0·21% (0·04-1·15; 10/3425) in children who received their first dose at 6-8 weeks, and 0·05% (0·00-1·32; 3/2902) in children who received their first dose at birth. The difference was not statistically significant in children who received their first dose at 6-8 weeks and children who received their first dose at birth after adjusting for the study period, region, and maternal HIV status (test of moderators p=0·37).

INTERPRETATION

In children of HBsAg-negative mothers, the risk of infection might be minimal even with the vaccination starting at 6-8 weeks, without clear additional benefit from HepB-BD. When births take place at home and timely administration of HepB-BD is challenging, antenatal HBsAg screening and selective HepB-BD might allow efficient allocation of resources to mother and child pairs at high risk compared with universal HepB-BD.

FUNDING

None.

TRANSLATION

For the French translation of the abstract see Supplementary Materials section.

The Changing Demographics of Hepatitis B Virus Infection

Hepatitis B virus infection remains a global public health problem with changing epidemiology due to several factors including vaccination policies and migration.

Progress on the elimination of viral hepatitis in Zimbabwe: A review of the policies, strategies and challenges

Very few low-income countries have developed national plans to achieve the viral hepatitis elimination targets set in the World Health Organization (WHO) strategy. We reviewed the policy environment, strategies and challenges on the fight against viral hepatitis in Zimbabwe. The review focussed on the Ministry of Health and Child Care (MoHCC) policy documents, strategic plans and reports. We performed key informant interviews to enhance evidence generated from the document review. Twelve documents were reviewed and interviews with 10 key informants were completed. The MoHCC established a technical working group to work towards elimination of viral hepatitis. The technical working group drafted a strategic plan for elimination of viral hepatitis; however, it is still awaiting implementation. Key strategies that are working well include screening of donated blood for transfusion, safe injection practices and hepatitis B virus (HBV) three-dose vaccination. Current challenges in the drive towards elimination of viral hepatitis include poor to non-existent surveillance systems, lack of epidemiological data, absence of the HBV vaccine birth dose and lack of systematic screening and treatment services for viral hepatitis. In conclusion, despite political will demonstrated towards achieving viral hepatitis elimination, substantial investment and work are required to implement the strategic plan and realize significant success.

The positive rates of hepatitis B surface antibody in youths after booster vaccination: a 4-year follow-up study with large sample

BACKGROUND

Hepatitis B virus (HBV) infection is still a public issue of the world. Hepatitis B vaccination is widely used as an effective measure to prevent HBV infection. This large-sample study aimed to evaluate the positive rates of hepatitis B surface antibody (anti-HBs) in youths after booster vaccination.

METHODS

A total of 37,788 participants were divided into two groups according to the baseline levels of anti-HBs before booster vaccination: the negative group (anti-HBs (-)); the positive group (anti-HBs (+)). Participants were tested for anti-HBs levels after receiving a booster vaccine 1 year and 4 years.

RESULTS

The positive rates of anti-HBs were 34.50%, 73.8% and 67.32% before booster vaccination at 1 year and 4 years after vaccination, respectively. At four years after the booster vaccination, the positive rates of 13 to 18 years were 47.54%, which was the lowest level among all youths age groups. In the anti-HBs (-) group, the positive conversion rates of anti-HBs were 74.62% at 1 year after receiving a booster vaccine, and 67.66% at 4 years after vaccination. In the anti-HBs (+) group, the positive maintenance rates of anti-HBs were 70.16% after 1 year, and 66.66% after 4 years. Compared with the baseline anti-HBs (+) group, the positive rates of the baseline anti-HBs (-) group were higher at 1 year and 4 years after receiving the booster vaccine.

CONCLUSIONS

 The positive rates of anti-HBs declined over time, especially the positive maintenance rates were the lowest at age of 13 to 18 years.