Table.

Antiretroviral-based HIV prevention studies

	Study population	Location	Route of HIV transmission	Intervention	Outcome	Comments
CAPRISA 0042	889 heterosexual women at high risk of infection, aged 18–40 years	South Africa	Vaginal	Coitally-dependent TFV 1% gel (two doses up to 12 h precoitus and postcoitus)	39% protection; 54% protection calculated in participants using >80% of doses	High TFV-DP concentration in vaginal and cervical tissue critical for efficacy
iPrEX4	2499 MSM at high risk of infection; approximately 70% of mixed ethnicity; mean age in TDF/FTC group 27·5 years	North and South America, Thailand, South Africa	Rectal/penile	Daily oral TDF/FTC	44% protection; 92% protection calculated for subjects with detectable drug concentrations	High TFV-DP concentrations in rectal tissue might be critical for efficacy
TDF25	1200 sexually active adults; 55% male, 45% female; 94% unmarried; approximately 90% age 21–29 years	Botswana	Vaginal/penile	Daily oral TDF/FTC	63% protection	>30% did not complete study; cannot draw definitive conclusions for women and men separately
PIP6	4747 heterosexual serodiscordant couples; 38% negative-female, 68% negative-male partner; 98% married; median age 33 years	Botswana, Kenya, Rwanda, South Africa, Tanzania, Uganda, Zambia	Vaginal	Daily oral TDF or TDF/FTC	62% protection with TDF alone; 73% protection with TDF/FTC	Discordant couples may be a distinct, unique population
FEM-PrEP7	1951 heterosexual women at high risk of infection aged 18–35 years	Kenya, South Africa, Tanzania	Vaginal	Daily oral TDF/FTC	Trial discontinued for futility in April, 2011	Adherence assessment with monthly clinical samples to measure drug concentration is pending
VOICE (MTN-003)3	5029 heterosexual women aged 18–45 years in high-prevalence areas	Uganda, South Africa, Zimbabwe	Vaginal	Daily oral TDF or daily oral TDF/FTC or daily topical TFV gel	Oral TDF group discontinued for futility in September, 2011; TFV 1% gel and placebo gel groups discontinued for futility in November, 2011; oral TDF/FTC group continues	For TDF, the tissue concentration may be critical; for TFV 1% gel, adherence analysis is pending
HPTN 0521	1763 heterosexual serodiscordant couples; 50% negative-female, 50% negative-male partner; 94% married; 61% aged 26–40 years	Botswana, Kenya, Malawi, South Africa, Zimbabwe, Brazil, India, Thailand	Vaginal/penile	Immediate or delayed ART in HIV-infected partner	96% protection	Suppression of viraemia on therapy assured by routine monitoring

MSM=men who have sex with men. TDF=tenofovir disoproxil fumarate. TFV=tenofovir. TFV-DP=tenofovir diphosphate. FTC=emtricitabine. ART=antiretroviral therapy.