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.

Where PEP is recommended, it should be prescribed and started as soon as possible after the exposure and within 72 hours.

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 http://arv.ashm.org.au/images/Australian_National_PrEP_Guidelines.PDF

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%.

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