Post-Exposure Prophylaxis for HIV Exposure
Introduction to PEP Regimens
- The Centers for Disease Control and Prevention (CDC) recommends bictegravir/emtricitabine/tenofovir alafenamide (BIC/FTC/TAF) or dolutegravir (DTG) plus tenofovir alafenamide (TAF) or tenofovir disoproxil fumarate (TDF) plus emtricitabine (FTC) or lamivudine (3TC) as the preferred HIV PEP regimens, initiated as soon as possible within 72 hours of exposure and continued for 28 days 1, 2, 3
Timing of PEP Initiation
- PEP should be initiated as soon as possible after exposure, ideally within 24 hours, but no later than 72 hours, as efficacy decreases with delayed initiation 3, 4
- The first dose should not be delayed due to pending laboratory test results 4
Recommended PEP Regimens
- The CDC recommends bictegravir/emtricitabine/tenofovir alafenamide (BIC/FTC/TAF) as a single-tablet regimen for adults and adolescents 1, 2
- Dolutegravir (DTG) plus (tenofovir alafenamide [TAF] OR tenofovir disoproxil fumarate [TDF]) plus (emtricitabine [FTC] OR lamivudine [3TC]) is also recommended 1, 2
Duration of PEP
Laboratory Testing and Follow-up
- Perform HIV testing using rapid (point-of-care) or laboratory-based antigen/antibody combination (Ag/Ab) test, or both, at the initial assessment 2
- For persons with long-acting injectable PrEP exposure in the past 12 months, add a diagnostic HIV nucleic acid test (NAT) 2
- Assess for medical comorbidities, current medications, and allergies at the initial assessment 1, 2
- Perform interim HIV testing with both laboratory-based HIV Ag/Ab test plus diagnostic HIV NAT at 4-6 weeks after exposure 1, 2
- Conduct final HIV testing using laboratory-based HIV Ag/Ab combination immunoassay and diagnostic HIV NAT at 12 weeks after exposure 1, 2
Indications for PEP
- PEP is recommended when an exposure has occurred within the past 72 hours that presents a substantial risk for HIV transmission and the source has HIV without sustained viral suppression or their viral suppression status is unknown 2
- Case-by-case determination is required when an exposure has occurred within 72 hours that presents substantial risk, but the source's HIV status is unknown 2
Transition to PrEP After PEP
- Consider immediate transition from PEP to PrEP for persons with anticipated repeat or ongoing potential HIV exposures 1, 2
- Perform HIV testing at the completion of the PEP regimen before transitioning to PrEP 2
Common Pitfalls and Caveats
- Delaying PEP initiation beyond 72 hours significantly reduces effectiveness 3
- Incomplete adherence to the full 28-day course reduces effectiveness 5
- Failure to consider drug interactions with the patient's current medications 1, 2
- Not providing adequate follow-up for medication adherence and toxicity monitoring 6
HIV Post‑Exposure Prophylaxis (PEP) Initiation and Complementary STI Screening
PEP Initiation Criteria
- For individuals with recent unprotected sexual exposure, start PEP immediately when the source partner is known to be HIV‑positive without sustained viral suppression, has an unknown suppression status, or belongs to a high‑prevalence population. Prompt initiation (ideally within 24 h, but no later than 72 h) maximizes preventive efficacy. 7
PEP Contraindications
- PEP should not be offered to persons who are already HIV‑positive or when the source partner has a confirmed HIV‑negative test; in these scenarios, prophylaxis provides no benefit. [7][8]
Testing When Initial HIV Test Is Refused
- If a high‑risk individual declines baseline HIV testing, PEP should still be started because delaying therapy increases the risk of seroconversion; testing can be performed subsequently. 8
Additional STI Screening Recommendation
- Hepatitis C testing is advised when the exposure involved blood contact or when the source partner is at high risk for hepatitis C, ensuring comprehensive evaluation of blood‑borne infections. 8