The human immunodeficiency virus (HIV) is the virus that causes acquired immune deficiency syndrome (AIDS). It is spread through infected bodily fluids that enter the blood stream of an uninfected person. Transmission most commonly occurs during anal or vaginal sexual intercourse, when injection drug users share needles, or when a health care worker is pricked with a needle that contains infected blood. Additionally, a pregnant woman who is HIV positive can transmit HIV to her child during delivery or while breast feeding. An HIV prophylaxis is a treatment aimed at preventing the transmission of HIV; there are two kinds of HIV prophylaxis: pre-exposure prophylaxis and post-exposure prophylaxis.
Pre-exposure prophylaxis (PrEP) is in its infancy. In 2010, the Centers for Disease Control (CDC) was in the process of evaluating whether a combination of two antiretrovirals — drugs already used to treat HIV — could keep HIV from taking hold in the body. Clinical trials were being conducted among populations at risk for HIV in several countries, including the United States, Thailand, and Botswana, but not enough evidence had been gathered for a firm conclusion about the efficacy of PrEP.
Post-exposure prophylaxis (PEP) has a longer and better established track record. This kind of HIV prophylaxis involves giving a 28-day course of antiretrovirals to a person who has come into contact with the bodily fluids of someone with HIV. Most commonly, PEP is used when a health care worker is stuck with a needle containing the blood of an HIV-positive patient. PEP is also given to infants whose mothers test HIV-positive. More rarely, HIV prophylaxis is sometimes used as a "morning after" medication for rape victims, those who have had consensual sex with a person who has or is likely to have HIV, and injection drug users.
Studies of health care workers and infants whose mothers are HIV positive have shown that HIV prophylaxis is most effective if started within 36 to 72 hours. After 72 hours, it is considered ineffective. Among health care workers, completing the full course of PEP decreases the odds of HIV infection by 79 percent.
Non-occupational post exposure prophylaxis (nPEP) is still a somewhat cloudy issue. The CDC recommends that an individual who has had non-occupational exposure to the bodily fluids of an infected individual and seeks help within 72 hours be placed on a 28-day course of antiretrovirals. Some people, however, may not know the HIV status of the source individual. A rape victim, for instance, might have no idea of her rapist's sexual history or HIV status. The CDC remains largely silent on this issue, stating only that the decision to initiate HIV prophylaxis when the HIV status of the source individual is unknown should be made on a case-by-case basis.
HIV prophylaxis is by no means an easy fix to the problem of HIV exposure. Antiretrovirals are expensive, often prohibitively so for people without health insurance. Additionally, many people suffer severe side effects while taking them. Common side effects include nausea, vomiting, diarrhea, headache, and fatigue. Sometimes the side effects are so distressing that individuals are unable to complete the full 28-day course of the prescribed medication.
Repeated use of antiretrovirals may increase a person's risk of acquiring a treatment-resistive form of HIV. According to the CDC, however, treatment with antiretrovirals after exposure to HIV is currently the best HIV prophylaxis possible. More specific information about the CDC can be found on its website.