Prospective evaluation of clinical signs/symptoms of STIs on the day of and last seronegative visit prior to seroconversion.

*p-value calculated using Fisher's exact test. a2 Zambia subjects missing data on cystitis and lower abdominal pain because seroconversion detected between screening and enrollment visits.p值通过费希尔精确检验（Fisher's exact test）计算得到。a2组赞比亚受试者因在筛查与入组访视之间检测到血清转换，缺失膀胱炎及下腹痛相关数据。