<prompt> tafadhali geuza maudhui haya ya swahili kwenda kwa kiingereza.wakati wa utafiti huo uliochukua takriban miaka mitatu,watafiti waliwatumia wanawake 2000 wasio na virusi vya ukimwi kati ya miaka 18 hadi 30, na kuwapatia nusu yao dawa ya placebo na nusu nyengine wakapewa dawa ya kwenye sehemu za siri tenofivir,ambayo ni dawa ya kukabiliana na virusi vya ukimwi.  <response>: more than 16,000 hiv-negative men and women between the ages of 18 to 30 years participated in the study; half of these participants received the prime-boost vaccine regimen and half received placebo. 