Post-exposure prophylaxis (PEP) was first introduced in 1998 to health-care professionals in San Francisco who took care of HIV patients. When they encountered accidental needle-stick injuries, they risked being infected by HIV. Occupational PEP was then administered to suppress the virus. This has since become a standard care for all medical workers.
PEP involves a course of anti-retroviral drugs to be first administered within 72 hours of exposure. One such regime comprises the following drugs, to be taken twice a day:
- One tablet of Zidovudine 300mg/Lamivudine 150mg; and
- Two tablets of Lopinavir 200 mg/Ritonavir 50 mg.
The entire regime, which lasts 28 days, has to be completed. Otherwise, its effectiveness will be greatly reduced.
Studies have shown that PEP can reduce chances of HIV infection by as much as 80% if administered in a timely manner.
Non-occupational PEP (NOPEP)
NOPEP is for those who may have been infected by HIV through non-occupational means. These include sexual contacts, sharing of intravenous needles and prevention of mother-to-child transmission.
NOPEP works on the same principles as PEP. Although there is supportive evidence of its effectiveness based on biologic plausibility and animal studies, there is no absolute proof that it can effectively decrease the risk of HIV infection.
An NOPEP regime costs several hundred U.S. dollars and more. Not only must treatment commence within the window period, patients will also have to deal with unpleasant side effects (including nausea, diarrhoea, rashes, headaches etc.), as well as the anxiety of being possibly infected. They also need consultations and follow-up tests at intervals of between three and six months. In addition, NOPEP does not prevent transmission of other sexually transmitted infections (STI). Hence, it should not be treated as a panacea.
HIV Exposure Risks
The list below shows the estimated risk of HIV infection arising from different circumstances:
- Needle stick injury: 1/300
- Receptive anal intercourse: 1/100
- Receptive vaginal intercourse: 1/1000
- Insertive vaginal intercourse: 1/2000
- Insertive anal intercourse: 1/2500
- Receptive oral sex with ejaculation: 1/2500
- Sharing needles: 1/150
- Exposure to saliva, urine, tears and sweat are generally risk-safe.
The exact probability of infection is hard to determine because many factors are involved, including the viral load, presence of other STIs, strength of one’s immune system, etc.
PEP Starter Packs
Since PEP is most effective when started as soon as possible after exposure, it is a good idea for serodiscordant/magnetic couples (one partner is HIV+ while the other is HIV-) to have a PEP starter pack on standby. These can be obtained through the HIV specialist whom the HIV+ partner consults.
You may check: Beauty Our Way: Happy To Be Nappy.
Even with safer practices, accidents (e.g. condom breakage) can occur when there is no convenient access to a source of PEP. The starter kit can then be deployed within moments of exposure to minimize the chances of potential infection.
Pre-exposure Prophylaxis (PrEP)
This is a further extension of the principles of PEP and NOPEP, where an anti-retroviral regime is administered before high-risk exposure.
PrEP is now the most promising research in HIV prevention efforts as scientific investigation of vaccines and microbicides continues. However, debate is still on-going in the medical field as to its effectiveness. This is because even for occupational PEP, there have been documented cases of seroconversion. There is also the danger that people will be lulled into complacency, thinking that they can continue to engage in unsafe sexual practices.
A more fundamental solution is to prevent/minimize exposure to HIV through safer sex practices. Compared to the PEP treatment regime, using condoms is much cheaper, convenient and relatively hassle-free.