Congenital transmission of hepatitis B antigen in Nigerians

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.

Risk factors for hepatitis B infection during pregnancy in a Nigerian obstetric population

We aimed to assess the risk factors for hepatitis B infection among pregnant women in Enugu, southeast Nigeria. This was a prospective case-control study of risk factors for hepatitis B surface antigen positivity among pregnant women seen in two tertiary health institutions in Enugu, southeast Nigeria. It was carried out over an 8-month period, January - August 2005. Of the 1,499 pregnant women attending the antenatal clinic, 4.6% (n = 69) were seropositive for hepatitis B surface antigen. A total of 35 (50.7%) HBsAg positive women and 71 negative controls were interviewed. The risk factors for HBsAg were present in 71% (n = 25) of the positive cases, while only 27% (n = 19) of the negative cases had risk factors. The significant risk factors for HBsAg positivity were higher mean parity, higher number of sexual partners since sexual debut, polygamy and previous positive history of sexually transmitted diseases (STD) (p < 0.05). The two groups did not differ with respect to presence of tattoo or scarification marks, positive history of jaundice or contact with a jaundiced patient, previous blood transfusion or contact with blood products, intravenous drug abuse or sharing personal instruments (p > 0.05). Screening pregnant women for hepatitis B infection on the basis of presence of risk factors may not effective. Universal antenatal screening for HBsAg, health education aimed at reducing risk factors and immunisation of all newborn and those at risk of hepatitis B is advocated.

A comparison of human immunodeficiency virus (HIV) seropositivity and hepatitis B surface antigenemia (HBs Ag) among the same group of apparently healthy pregnant women in Lagos, Nigeria: a preliminary report

Two hundred and fifty apparently healthy pregnant women attending the Obstetrics and Gynecology Clinic of the Lagos University Teaching Hospital (LUTH), Lagos, Nigeria were screened for a comparison of the prevalence of HIV seropositivity and hepatitis B surface antigenemia (HBs Ag) amongst them. The Karpas AIDS cell test for HIV seropositivity and Bioman Hepatitis test kits were used as described by the manufacturers. HIV seropositive cases were confirmed using the Western blot test. Results revealed that out of the 250 pregnant women screened, 2 (0.8%) and 11 (4.4%) were HIV-1 and HBs Ag seropositive, respectively. However, the same 2 pregnant women now constituting 2 (18.2%) of the 11 HBs Ag positive pregnant women were simultaneously HIV-1 seropositive. Antibody to HIV-2 was not recorded in all HIV seropositive cases. This is the first report on the simultaneous prevalence of HBs Ag and HIV seropositivity among apparently healthy pregnant women in Lagos, Nigeria.

Hepatitis B vaccine in pregnancy: immunogenicity, safety and transfer of antibodies to infants

To determine the safety and immunogenicity of hepatitis B vaccine in pregnancy, 72 pregnant Nigerians who were negative for markers of hepatitis B virus (HBV) were given two intramuscular doses of vaccine (Heptavax, Merck) in the third trimester. One month after the second dose (at T2), 84% were anti HBs positive. No significant effect was observed in the mothers or their newborns. Passive transfer of anti HBs occurred in 59% of the newborns. The antibodies disappeared rapidly in these infants and by 3 months only 23% had detectable antibodies. No HBsAg carrier status developed in this group. In contrast, the infants born to HbsAg positive mothers had a cummulative rate of HBV events of 20%. It is concluded that HBV vaccine is safe and immunogenic in pregnant females. The passive immunity conferred on the infants is of short duration. Therefore, infants in endemic areas should be vaccinated early, preferably within 3 months of birth. Vaccination of pregnant mothers may provide adequate protection before the child is vaccinated.