- If the subject is female, and the potential of pregnancy exists, it must be asked prior to immunization by the study nurse. According to the protocol d'immunisation du Québec, Engerix-B is not contra-indicated during pregnancy. However, if a participant thinks she could be pregnant (sexually active and no oral contraception or intra uterine device), a pregnancy test will be carried out. In case of pregnancy, the booster vaccination will be performed after delivery.