Low Immunogenicity of Recombinant Hepatitis B Vaccine Derived from Hansenula polymorpha in Adults Aged Over 40 Years.

The Brazilian recombinant hepatitis B vaccine (VrHB-IB) is based on the expression of the recombinant antigen in Hansenula polymorpha yeast cells. Currently, data on the immunogenicity of this vaccine in older adults are nonexistent. This study aimed to evaluate the immunogenicity of VrHB-IB in adults over 40 years of age. From May to October 2011, 235 rural settlers between 2 and 93 years of age from the State of Goias in Brazil were eligible for vaccination. Of these, 180 accepted the first dose of the vaccine and 106 (58.9%) completed the vaccination schedule. Multivariate analysis revealed that individuals ≥ 40 years of age responded significantly less well to vaccination than younger adults. Also, a greater proportion of male nonresponders was observed (versus women; P = 0.02). These results point to the need for better evaluation of the immunogenicity of VrHB-IB in older adults. © The American Society of Tropical Medicine and Hygiene.