When to Prescribe PEP
Ultimately, the decision to prescribe PEP needs to be made on a case-by-case basis, considering all the variables. These guidelines are not prescriptive, but put forward cases where PEP is recommended and the benefit of treatment is likely to exceed harm. Situations where there is greater uncertainty or complexity, such as known or suspected antiretroviral resistance in the source, pregnancy, breastfeeding or chronic hepatitis B or C, should be discussed with a physician experienced in this area.
As for the number of drugs recommended for treatment, there is no direct evidence to support the greater or lesser efficacy of three over two-drug preventative regimens. It is an extrapolation of any possible benefit conferred by increased numbers/classes of drugs for HIV treatment while also taking into account potential side effects, toxicity, adherence and cost-effectiveness of adding a third drug. See Tables 3, 4 and 5 for PEP recommendations.
PEP should generally not be prescribed after 72 hours, but may be considered on a case-by-case basis in consultation with a specialist.
Linkage to a specialist for discussion regarding PrEP should be considered. See the PrEP guidelines for further guidance at https://www.ashm.org.au/HIV/PrEP/
Table 3. PEP recommendations after NON-OCCUPATIONAL exposure to a KNOWN HIV status source
| PEP recommendation | |||
|---|---|---|---|
| Type of exposure with known HIV positive source | Estimated risk of HIV transmission per exposure if source NOT on antiretroviral treatment | Source not on treatment or on treatment with detectable or UNKNOWN viral load | Source viral load KNOWN to be undetectable |
| Receptive anal intercourse (RAI) - ejaculation - withdrawal |
1/70 1/155 |
3 drugs |
Not recommended* |
| Shared needles and other injecting equipment | 1/125 | 3 drugs | Not recommended* |
| Insertive anal intercourse (IAI) (uncircumcised) | 1/160 | 3 drugs | Not recommended* |
| Insertive anal intercourse (IAI) (circumcised) | 1/900 | 3 drugs | Not recommended* |
| Receptive vaginal intercourse (RVI) | 1/1250 | 3 drugs | Not recommended* |
| Insertive vaginal intercourse (IVI) | 1/2550 | 3 drugs | Not recommended* |
| Receptive or insertive oral intercourse | Not measurable | Not recommended† | Not recommended |
| Mucous membrane and non-intact skin exposure | < 1/1000 | 3 drugs | Not recommended |
* Provided the source history is reliable, they are compliant with medication, attend regular follow-up and have no intercurrent STI.
† PEP may be recommended for receptive oral intercourse with ejaculation if the exposed person has a breach in their oral mucous membrane.
Table 4. PEP recommendations after NON-OCCUPATIONAL exposure to a source with UNKNOWN HIV status
| Type of exposure with unknown HIV positive source | Estimated risk of HIV transmission per exposure | PEP recommendation |
|---|---|---|
| Receptive anal intercourse (RAI) - ejaculation - withdrawal |
1/700* 1/1550* |
2 drugs if source MSM or from high prevalence country (HPC) |
| Shared needles and other injecting equipment | 1/12,500† (1/1250 – 1/415‡ if source MSM) |
2 drugs if source MSM or from HPC |
| Insertive anal intercourse (IAI) (uncircumcised) | 1/1600* | 2 drugs if source MSM or from HPC |
| Insertive anal intercourse (IAI) (circumcised) | 1/9000* | Consider 2 drugs if source MSM or from HPC, particularly if concurrent STI, trauma or blood |
| Receptive vaginal intercourse (RVI) | 1/1,250,000^ | Not recommended Consider 2 drugs if source MSM or from HPC |
| Insertive vaginal intercourse (IVI) | 1/1,250,000^ | Not recommended Consider 2 drugs if source from HPC |
| Receptive or insertive oral intercourse | Not measurable | Not recommended |
| Mucous membrane and non-intact skin exposure | < 1/10,000* (MSM exposure) | Not recommended |
| Needlestick injury (NSI) from a discarded needle in community | Not measurable | Not recommended |
* Based on estimated seroprevalence 10% (9.6%) in MSM.
† Based on estimated seroprevalence 1.0%.
‡ Based on estimated seroprevalence of 29%.
^ Based on estimated seroprevalence 0.1%.