Although it is vital that people with suspected HIV receive immediate post-exposure treatment, researchers have found that people in high-risk groups may benefit from pre-exposure preventive treatment. The study is published in the Canadian Medical Association Journal (CMAJ).
Dr. Isaac Bogoch, Harvard Medical School and the Division of Infectious Diseases, Massachusetts General Hospital, Boston, and his colleagues, explained:
“Although postexposure prophylaxis has a long history of success, newer methods such as pre-exposure prophylaxis and earlier treatment in the course of infection (‘treatment as prevention’) are being implemented with some success.”
Researchers from Massachusetts General Hospital, Brigham and Women’s Hospital and Harvard Medical School, Boston, Massachusetts and Sunnybrook Health Sciences, Toronto, conducted a review of studies about pre-exposure prevention and early initiation of antiretroviral therapy from 1990 to 2012 in order to provide physicians with current pharmacologic prevention methods.
HIV is most commonly transmitted through unprotected sex (anal or vaginal), and contaminated needles. Although the disease can be transmitted from mother to baby, the researchers did not include this in the review.
After evaluating whether an individual has been exposed to the disease, post-exposure treatment (prophylaxis) should be started within 72 hours and be continued for 28 days.
If the patients situation is considered low-risk but not completely without risk, the patient and the physician can decide upon the risks of transmission and whether to treat prophylactically. Current practice recommends a two-drug regimen of tenofovir in addition to emtricitabine. For individuals with high-risk exposure, a third drug is also recommended.
The researchers said: “Evidence for quickly starting prophylaxis and a four-week duration of therapy stem from macaque models of transmission, in which starting prophylaxis later and shorter durations of therapy resulted in higher rates of HIV seroconversion [development of antibodies against HIV]).”
According to the researchers, pre-exposure prophylaxis has been demonstrated to prevent HIV infection before individual at high risk are exposed to the virus. High-risk populations include:
- intravenous drug users
- men who have sex with men
- women in areas with a high prevalence of HIV, are exposed to the virus
For instance, a recent trial involving 900 women from a region with high HIV prevalence demonstrated that application of a topical vaginal microbicide 12 hours before and after sex reduced HIV infection rates by 39%.
The researchers explained: “All pre-exposure prophylaxis interventions should be considered one part of a more comprehensive plan for preventing the spread of HIV infection, including standard counseling on safer sexual practices and condom use, testing for and treating other sexually transmitted infections and, in select circumstances, male circumcision and needle exchange programs.”
They conclude:
“Whereas pre-exposure prophylaxis may be reserved for people with the highest risk of exposure, the trend of treating HIV at higher CD4 T cell counts earlier in infection will likely show the most promise as a pharmacologic strategy for preventing the transmission of the virus.”
The researchers highlight that although pre-exposure prophylaxis is promising, which individuals would benefit most, the possibility of drug resistance and others remains unclear. Currently several trials are being conducted in order to determine effectiveness of early treatment.
Written By Grace Rattue