 Menstrual cycle 3: Sampling visits There will be 3 sampling visits, at about 9, 14 and 21 days after the start of menses. At each visit, subjects will have a cervico-vaginal examination, during which sampling of secretions and cells will be done for immunology tests. Also, blood will be collected for immunology tests, and subjects will have their temperature, blood pressure and heart rate measured. At the 1st and 3rd sampling visits only, blood and urine will be collected for routine laboratory safety tests also. 