Hepatitis B susceptibility, infection and vaccine-induced immunity among health personnel in Sokoto, Nigeria: a cross-sectional serological study

Background Health personnel in Nigeria have a high occupational risk of hepatitis B virus (HBV) infection, and vaccination status is usually established by self-report. The extent to which reported vaccination corresponds to serological protection has not been measured in northern Nigeria. We described HBV infection and immunity among health personnel, compared self-reported vaccination with serological markers and identified factors associated with vaccine-induced immunity, natural immunity and current infection. Methods We conducted an analytical cross-sectional serological study of 473 health personnel selected by multistage sampling from primary, secondary and tertiary facilities in Sokoto State between January and March 2023. An interviewer-administered semi-structured questionnaire was completed, and serum was tested for HBsAg, anti-HBs, anti-HBc, HBeAg and anti-HBe with a five-panel rapid test. Firth penalised logistic regression was used for each outcome. Results Current infection (HBsAg positive) was found in 7.8% (n = 37; 95% CI: 5.7–10.6) and evidence of any past or current infection in 17.1% (n = 81). Anti-HBs was detected in 16.5% (n = 78): 12.3% (n = 58) had vaccine-induced and 4.2% (n = 20) natural immunity, while 70.6% (n = 334) had no serological marker. Self-reported vaccination had a positive predictive value of 24.3% for vaccine-induced immunity (κ = 0.16). Among 96 participants who reported three or more doses, 69.8% (n = 67) had no detectable anti-HBs and six were HBsAg positive. Vaccine-induced immunity was associated with three or more reported doses (aOR 2.90; 95% CI: 1.37–6.22), positive attitude (aOR 1.98; 95% CI: 1.01–3.90), an employer request for vaccination status (aOR 2.05; 95% CI: 1.03–3.97) and insertion of tubes or catheters (aOR 2.75; 95% CI: 1.08–6.93). Natural immunity was more frequent in primary facilities (aOR 4.84; 95% CI: 1.56–15.30). Current infection was not associated with occupational exposures and was less frequent after more than 10 years of practice (aOR 0.23; 95% CI: 0.06–0.84). Conclusions Most health personnel in Sokoto had no serological protection against HBV, and self-reported vaccination overstated protection. Screening for HBsAg and anti-HBs at recruitment, documented vaccination with post-vaccination testing, and referral of infected staff for care should be part of routine occupational health services.