Immunogenicity of Four Doses of Double-Strength Intramuscular Hepatitis B

Background: Hepatitis B virus potentially accelerates graft rejection and mortality in renal transplantation population. Vaccination of graft candidates without prior immunization against HBV seems essential before transplantation but some candidates of transplantation have not received HBV vaccine at the time of receiving graft. We aimed to evaluate immunogenicity of an enhanced regimen (4 doses of double-strength intramuscular shots) after kidney transplantation in candidates without history of prior HBV vaccination. Methods: This quasi-experimental study was conducted, 49 renal graft recipients in Sina Hospital (Tehran University of Medical Sciences, Tehran, Iran) of age >18, receiving graft within past 6 months and negative history of hepatitis B vaccination from 2010-2011. Participants received 40 μg intramuscular (IM) shots of a recombinant vaccine in the months 0, 1, 2 and 6. The titer of HBsAb was measured 8 weeks after the 3rd and 4th injections. Cases with HBsAb titers less than 10 mIu/ml were considered as non-responder while antiHBs≥10 mIu/ml was considered protective. Results: The overall response rate was 57.14% (28/49 patients). Protective HBsAb titers were detected in 44.89% patients following 3rd dose and reached to 57.14% after injecting the 4th shots. The mean HBsAb titers were 50.00 (±88.35) mIu/ml and 229.45 (±356.56) mIu/ml after the 3rd and 4th shots respectively. Responders showed significantly younger age in comparison to non-responders (P=0.013). The vaccine was well tolerated in all patients with no side effects. Conclusions: Regarding the relative good response rate following HBV vaccination in graft recipients, we suggest a post-transplantation enhanced regimen of 4-dose double-strength IM shots against HBV in patients without prior immunization.