Arecent study in Kenya and Uganda evaluated the use of antiretroviral medications for the prevention of HIV type 1 transmission in heterosexual couples in which one partner was HIV-1 positive and the other wasn't infected. A total of 4,747 couples were followed. The seropositive partners weren't receiving antiretroviral therapy; 62% were men.

The noninfected partners were randomized to receive once-daily oral tenofovir disoproxil fumarate (TDF), 300 mg; TDF with emtricitabine (TDF-FTC), 300 mg and 200 mg, respectively; or placebo. Participants also received HIV-prevention services, including risk-reduction counseling, screening, condoms, and referrals for circumcision and postexposure prophylaxis.

A total of 1,584 partners received TDF, 1,579 received TDF-FTC, and 1,584 received placebo. The partners were followed for 36 months, and the authors determined that the medication-adherence rate during the follow-up period was 92%. A total of 82 partners developed HIV-1 infections after randomization: 17 in the TDF group; 13 in the TDF-FTC group; and 52 in the placebo group, which was discontinued (subjects taking placebo were then randomized into one of the active-treatment groups).

Relative to placebo, TDF offered a 67% reduction in the risk of HIV seroconversion and the TDF-FTC combination reduced the risk by 75%, although the difference between the two regimens wasn't statistically significant.

The authors state that these results show that prophylaxis among HIV-negative partners can reduce the transmission rate. They note, however, that in order to be successful, prophylactic medication needs to be accompanied by strategies for ensuring adherence, clinical monitoring, and access to antiretroviral therapy for infected people.

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