To the Editor. —Vaccination using a full course of three doses of HBV leads to the development of protective antibody to anti-HBs response in 85% to 95% of all vaccinees. A small proportion of vaccinees, 1 however, fail to develop anti-HBs titers of greater than 10 mIU/mL, the minimal titer considered to be protective. 2 Nonresponsiveness is thought to be associated with increasing age, obesity, smoking cigarettes, and certain immunogenetic status. Recently it has been reported that an important percentage of the nonresponders were positive for serum HBV DNA, detected by polymerase chain reaction. This was the case in four of six nonresponders in a study by Takahashi et al 3 and in 16 of 26 in a study by Luo et al. 4 We studied nonresponders among health care workers in Hospital of Orleans (France). Each health care worker was vaccinated with three doses of recombinant vaccine (Engerix-B) at