Lapphra KM, et al. – Authors here determined the need to revaccinate perinatally HIV–infected Thai adolescents against hepatitis B virus (HBV) infection. In this study, only half of perinatally HIV–infected adolescents were able to elicit anti–HBs response with a single–dose HBV vaccine. Revaccination with 3–dose schedule was required in in these adolescents who did not initiate highly active antiretroviral therapy (HAART) at the time of infant vaccination.