Prevalence of non-responsiveness to an indigenous recombinant hepatitis B vaccine: a study among South Indian health care workers in a tertiary hospital.

Objective: Health care workers (HCW) are at higher risk of contracting HBV infection. Non-response to HBV vaccine is one of the major impediments to prevent healthcare associated HBV infection (HAHI). We estimated the prevalence of non-responsiveness to initial 3-dose regimen of an indigenous recombinant HBV vaccine (GeneVac-B) among South Indian HCWs and typed the HLA in non-responders.

Methods: Of the 778 subjects screened over 1 year, 454 completed all three doses of the hepatitis B vaccination. Anti-HBs titers were estimated by microparticle enzyme immunoassay AxSYM AUSAB, (Abbott, Germany). HLA typing was done using SSP-PCR assay AllSet+™ Gold SSP (Invitrogen, USA).

Results: The overall seroconversion rate (anti-HBs>10 mIU/mL) was 98.89% wherein 90.8% had titers>1000mIU/mL, 7.6% had titers 100-1000mIU/mL, 0.43% had titers<100 mIU/mL and 1.1% were non-responsive (<10 mIU/mL) to the initial 3-dose regimen. Antibody titers<1000 mIU/mL were significantly associated with the highest quartile of body mass index (BMI) (P<0.001). We found no significant difference in seroprotection rate between gender (P=0.088). There was no difference in seroprotection rates among various ethnic groups (P=0.62). Subjects who were non-responsive in our study had at least one HLA allele earlier known to be associated with non-responsiveness to the vaccine.

Conclusions: Our findings suggest that non-response to HBV vaccine is not a major impediment to prevent HAHI. Robust seroprotection rates can be achieved using this indigenous HBV vaccine. However, gender and BMI might influence the level of anti-HBs titers. We recommend the use of this cost effective HBV vaccine as well as postvaccination anti-HBs testing to prevent HAHI among HCWs.