Low dose revaccination induces robust protective anti-HBs antibody response in the majority of healthy non-responder neonates.
A sizeable proportion (1-10%) of healthy adults and to lesser extent neonates vaccinated with triple 10 microg hepatitis B (HB) vaccine fail to mount a protective antibody response. Revaccination with the same vaccine dose has proved to be effective in a significant number of primary non-responders. The influence of revaccination with lower vaccine doses however has not been studied adequately in non-responder neonates. This study was conducted to evaluate the influence of supplementary vaccination with a single low and standard dose of a recombinant hepatitis B (HB) vaccine in healthy Iranian non-responder neonates to primary vaccination. Iranian neonates unable to respond to primary vaccination with 10, 5 or 2.5 microg doses of recombinant HB vaccine were revaccinated with a single additional dose of the same concentration. Serum anti-HBs antibody titer was measured by sandwich ELISA. Administration of a single additional dose induced seroprotection (anti-HBs> or =10IU/L) in 10/12 (83%), 10/12 (83%) and 21/24 (87.5%) of non-responder neonates in 10, 5 and 2.5 microg vaccine recipients with geometric mean titers (and 95% confidence limits) of 1358 (258-7142), 401 (79-2038) and 164 (62-433) IU/L, respectively. The log-transformed antibody titer obtained for the 10 microg dose recipients was significantly higher than that of the 2.5 microg dose vaccinees (p=0.028). No significant differences in anti-HBs titer were observed between other groups of vaccinees. However, the total seroprotection rates obtained after administration of four low doses of 2.5 and 5 microg were significantly higher than that obtained after administration of the classical three 10 microg doses (p=0.029 and p=0.006, respectively). The total seroprotection rates were similar between all groups of vaccines receiving four doses of 2.5, 5 and 10 microg vaccine doses. These results indicate that a significant proportion of non-responder neonates can be induced to develop a protective anti-HBs response following revaccination with a single low dose vaccine. Thus adaptation of four low dose (2.5 or 5 microg) vaccination is expected to induce higher seroprotection rate and lower or comparable anti-HBs antibody titer in healthy neonates.
Department of Immunology, School of Public Health, Medical Sciences/University of Tehran, Tehran 14155, Iran.
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Jafarzadeh
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Zarei
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Shokri
D004306:Dose-Response Relationship, Immunologic; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D005260:Female; D006509:Hepatitis B / Q000276:immunology / Q000517:prevention & control*; D006510:Hepatitis B Antibodies / Q000097:blood*; D017325:Hepatitis B Vaccines / Q000008:administration & dosage* / Q000276:immunology*; D006801:Humans; D007117:Immunization, Secondary; D007231:Infant, Newborn; D007492:Iran; D008297:Male; D014614:Vaccines, Synthetic / Q000008:administration & dosage / Q000276:immunology
D006510:Hepatitis B Antibodies; D017325:Hepatitis B Vaccines; D014614:Vaccines, Synthetic