Seroconversion of Hepatitis B Vaccine in Young Children in the Kassena Nankana District of Ghana: A Cross-Sectional Study

Abstract

BackgroundHepatitis B Virus (HBV) infection is an important public health problem that requires high priority efforts towards prevention and control. Active immunization is the single most important and effective preventive measure against HBV infection. As a protective measure, Ghana introduced the mass immunization program against hepatitis B infection in children in 2002 in her Expanded Programme on Immunization (EPI). This study evaluated seroconversion (the point in time when the amount of antibody in the blood becomes detectable) and seroprotection (the point in time when the amount of antibody in the blood is enough to confer protection from the antigen that induced it production) status of children under this mass immunization program and measured their antibody levels five years after immunization.Materials and Method200 archived plasma samples of children between the ages of 1–10 years were retrieved from a previous cross-sectional study by researchers from NHRC between 2009 and 2010. Of these, 104 have completed the EPI and were screened for HBsAg. Those found to be HBsAg-seronegative were stratified into three groups according to their age at which the last vaccine was administered. Their anti-HBsAg titer levels were estimated by enzyme linked immunosorbant assay (ELISA).ResultsTwo (1.9%) samples were HBsAg seropositive and were excluded from further analyses. 10 more samples were excluded from analyses because they were insufficient. The anti-HBs titers recorded ranged from 1.021 IU/L to 751.64 IU/L indicating a 100% seroconversion rate. In group one (0–6 months), 87.9% were seroprotected. Group two (2-3yrs) had 78.3% seroprotection and group three (3-5yrs) had 41.7% seroprotection. There was no significant difference between group 1 and 2. However, there was a significant difference between group 1 and 3 (p = 0.0137) and between group 2 and 3 (p = 0.0390) respectively. There was no significant difference between male and female children.ConclusionAll the children who received doses of hepatitis B vaccine at 6, 10 and 14 weeks in the immunization program seroconverted, but their levels of protection waned with increasing years. Booster doses are therefore recommended after 5 years.

Changes and analysis of anti‐HBs titres after primary immunization in 1‐ to 16‐year‐old Chinese children: A hospital‐based study

“…Figure clearly indicates that the protective levels waned with increasing age between 1 and 8 years old, the percentage of lower concentrations declined more rapidly and that of higher titres kept relatively stable, especially the rate of high‐responders without showing obvious increasing or decreasing trend, suggesting that high antibody levels may be maintained for longer. Some studies also demonstrated that antibody levels showed a significant decline in children after hepatitis B vaccination in infancy . The decline of antibody concentrations may be associated with hepatitis B vaccine type, dosage, different vaccination programmes, physical quality and vaccination age …”

“…Some studies also demonstrated that antibody levels showed a significant decline in children after hepatitis B vaccination in infancy. [14][15][16] The decline of antibody concentrations may be associated with hepatitis B vaccine type, dosage, different vaccination programmes, physical quality and vaccination age. [17][18][19][20] Surprisingly, the proportion of protected anti-HBs titres slowly increased for children older than 8 years old, and the trend in antibody levels for children aged 9-16 declined compared to that in the 1-9 age groups, being >10 mIU/mL and of >100 mIU/mL, respectively.…”

Immune Status of Cohort of Children Vaccinated against Hepatitis B Virus in Ekiti State over Ten Years after Incorporation into National Program on Immunization

“…The level of sero-conversion recorded in this study is very low when compared to studies from other countries within and outside Africa. Dassah S et al found 87.9%, 78.3% and 41.7% seroprotection after 0-6 months, 2-3 years and 3-5 yrs respectively after complete vaccination in Ghana [15], Chakraborty et al found 100% seroprotection (≥ 10 IU/L) in Bangladesh [16], Freitas da Motta et al found a seroconversion rate of 77% in preterm infants and 98% among full term infants 3 months after the third dose among vaccinated children in Brazil [17]. Other findings however shows similarity to ours revealing a decline of HBV vaccine protective levels with time after vaccination.…”

“…Lee, Chuanfang [23] postulated that the protection afforded by vaccination is long lasting even after antibody levels fall below 10 mIU/ml [23]. However, other studies has shown HBV prevalence despite the WHO established coverage and have recommended revaccination or booster doses [13][14][15][16][17][18][19][20][21].…”

Assessment of seroepidemic conditions of hepatitis B virus among people under 29 years of age and evaluation of the hepatitis B vaccine after 22 years in Jiangsu Province, China

“…There are many factors influencing the effectiveness of the vaccination. Some studies found that antibody levels showed a significant decline in children after HB vaccination in infancy [36][37][38]. One potential reason may be vaccination age [39,40].…”