- Women must be either post menopausal, or rendered surgically sterile or, if of child bearing potential, must have been practising a reliable form of contraception (oral contraception + a barrier method) for at least three months prior to the first dose of TroVax® and must continue while they are being treated with TroVax®. Men must practise a reliable form of contraception (barrier or vasectomy) while they are being treated with TroVax®.