For people at high risk of acquiring HIV through heterosexual activity, pre-exposure prophylaxis (PrEP) with antiretroviral medications can be another way of preventing infection, the CDC said.
In an interim guidance, developed while clinical trial data is accumulating, the agency cautioned doctors to ensure men and women starting PrEP are not already carrying the virus and to discuss the issues of pregnancy and adherence.
The guidance comes less than a month after the FDA approved the combination of tenofovir and emtricitabine, sold as Truvada in a single pill, for HIV prevention among adults. The combination is widely used as part of HIV treatment.
The agency noted that, in 2009, there were an estimated 48,100 new HIV infections in the U.S., with 27% of them in heterosexual men and women who don't use injection drugs.
The CDC's recommendations for the use of PrEP in heterosexuals, in the Aug. 10 issue of Morbidity and Mortality Weekly Report, mirror those developed earlier for prevention among high-risk men who have sex with men, with the key exception of counseling about pregnancy.
As part of a doctor's assessment of a woman's eligibility for PrEP, the agency recommends determining if she is planning to become pregnant, is currently pregnant, or is breastfeeding.
Once a woman is on PrEP, the agency recommends asking about her pregnancy status at each clinic visit; if she has become pregnant, the doctor should discuss what's known about the drugs and their effects on the fetus.
In fact, the CDC noted, available data on women taking the drug to treat HIV infection or to prevent mother-to-child transmission suggest there are no adverse effects on the fetus.
On the other hand, in the key clinical trials of PrEP in heterosexuals, women who became pregnant while on the study drug promptly stopped treatment so "the safety of chronic fetal exposure could not be assessed adequately," the agency reported.
The guidance is derived from outcomes in four clinical trials, whose results, taken together, suggest that PrEP can be safe and effective, the CDC said.
But the agency cautioned that doctors and those starting PrEP must understand that consistent adherence to the daily medication is essential. In the trials, the CDC noted, participants who acquired HIV tended to be those with low blood levels of the medication, suggesting they had not been taking the pills as prescribed.
Doctors should also caution those starting PrEP that the long-term safety of the drug combination in people with HIV is still not determined; healthcare providers should report any serious adverse events to the FDA's MedWatch.
The bottom line, the CDC said, is that PrEP "has the potential to contribute to safe and effective HIV prevention for heterosexually active adults" provided that:
- It is aimed at people at very high risk for HIV, such as those whose regular sexual partners are known to have the virus.
- The importance of adherence and its influence on efficacy is clearly discussed.
- Couples understand that although no adverse effects have been found among infants exposed to Truvada during pregnancy and breastfeeding, the data remain incomplete.
- PrEP is delivered as part of a set of prevention services, including counseling about risk-reduction and medication adherence, as well as easy access to condoms.
- STD testing occurs at least every 6 months, and treatment is provided when indicated.
- It is accompanied by monitoring of HIV status, pregnancy, side effects, adherence, and risk behaviors at each follow-up visit.
The guidance was developed by the CDC. Authors are employees of the agency.
- Reviewed by Robert Jasmer, MD Associate Clinical Professor of Medicine, University of California, San Francisco and Dorothy Caputo, MA, BSN, RN, Nurse Planner
Morbidity and Mortality Weekly ReportSource Reference: Smith DK, et al "Interim guidance for clinicians considering the use of preexposure prophylaxis for the prevention of HIV infection in heterosexually active adults" MMWR 2012; 61: 586-589.