The WHO aims to eliminate hepatitis B virus (HBV) as a public health problem by 2030. HBV vaccination has reduced HBV incidence and mortality and is a cornerstone of the WHO elimination strategy. Belgium introduced universal infant HBV vaccination in 1999, with temporary catch-up vaccination for 12-year-olds, thereby covering all individuals born since 1987. This nationwide serosurvey assessed vaccine-induced hepatitis B surface antibody (anti-HBs) prevalence and natural HBV exposure in Belgium in 2020. We analyzed 4955 left-over samples from SARS-CoV-2 sero-epidemiology studies in 2020. Samples from ambulatory patients outside lockdown periods were tested for anti-HBs and hepatitis B core antibodies (anti-HBc) to evaluate vaccine-induced vs. natural exposure-derived anti-HBs responses. Samples were stratified by region, 10-year age band, and sex, and were weighted to reflect the Belgian population. Overall, 47.3% (95%CI 45.6%-48.9%) of the Belgian population had anti-HBs ≥ 2 IU/L and was anti-HBc negative. Furthermore, 33.9% (95%CI 32.4%-35.5%) fulfilled the WHO-recommended threshold of anti-HBs ≥ 10 IU/L. Anti-HBc prevalence, indicating prior or current infection, was 3.8% (95%CI 3.2%-4.5%). Individuals born since 1987, thus eligible for universal vaccination, had higher anti-HBs (≥ 2 IU/L) and lower anti-HBc prevalences than those born before 1987 (71.6% vs. 31.4%, p < 0.001 and 0.8% vs. 5.9%, p < 0.001). Regional differences were observed with the lowest anti-HBc-/anti-HBs+ (≥ 2 IU/L) prevalence in Wallonia, and highest anti-HBc prevalence in the Brussels federal region. In weighted multivariate analysis, older age (aOR 0.96, 95%CI 0.96–0.97) and residency in Wallonia (aOR 0.80, 95%CI 0.69–0.93) were associated with lower anti-HBc-/anti-HBs+ (≥ 2 IU/L) positivity, while older age (aOR 1.03, 95%CI 1.03–1.04) and residency in Brussels (aOR 2.79, 95%CI 1.70–4.57), were associated with higher anti-HBc positivity. Belgium has achieved high levels of vaccine-induced protection, especially in cohorts born after the implementation of universal HBV vaccination. However, regional differences remain, highlighting the need for targeted efforts to improve coverage and reduce HBV exposure.
d’Almeida et al. (Wed,) studied this question.