- Women must be either post-menopausal, or rendered surgically sterile or, if of child-bearing potential, must have a negative pregnancy test prior to trial entry. Two reliable forms of contraception (oral contraception and a barrier method) must be used by all participants while they are being treated with the TroVax® vaccine. Females must continue to use this level of contraception for 3 months following the last trial treatment, and male patients must continue for 1 month.