7. Women of childbearing potential not using reliable and adequate contraceptive methods (defined as: use of oral, implanted, injectable, mechanical or barrier products for the prevention of pregnancy; practicing abstinence; sterile) during the 5 weeks re-boosting period including the DTH and for 2 weeks after the DTH test, or sexually active male subjects with partners of child bearing potential unwilling to practice effective contraception during the 5 weeks re-boosting period including the DTH and for 12 weeks after the DTH-test.