What is the recommended HIV testing schedule for a patient with a high-risk exposure and no post-exposure prophylaxis (PEP)?

HIV Testing Schedule After High-Risk Exposure Without PEP

For patients with high-risk HIV exposure who do not receive PEP, perform HIV testing at baseline, 4-6 weeks, 12 weeks, and conclude testing at 4 months (16 weeks) post-exposure. 1, 2

Baseline Testing (Immediately After Exposure)

• Perform a combined HIV antibody/antigen test (fourth-generation test) immediately to establish baseline HIV status 1, 2
• Add HIV nucleic acid test (NAT/RNA) if the patient has any symptoms suggestive of acute retroviral syndrome or received long-acting injectable PrEP in the past 12 months 1
• Do not delay testing or wait for results before counseling the patient about risk reduction 3, 1

Follow-Up Testing Schedule

At 4-6 Weeks Post-Exposure

• Perform both HIV antigen/antibody combination test AND HIV nucleic acid test (NAT) 1, 2
• This timing captures most acute infections that may have been missed at baseline 1

At 12 Weeks (3 Months) Post-Exposure

• Perform laboratory-based HIV antigen/antibody combination immunoassay AND HIV nucleic acid test (NAT) 1, 2
• This represents the standard window period for most HIV testing algorithms 3, 2

At 16 Weeks (4 Months) Post-Exposure

• Perform final HIV testing to definitively rule out infection 2
• Testing can be concluded at 4 months when using fourth-generation combination tests, as this exceeds the window period for all but the rarest cases 2

Critical Counseling Points

• Advise the patient to use barrier protection and avoid potential transmission activities during the entire 4-month follow-up period 3, 1
• Instruct the patient to seek immediate medical evaluation if they develop any acute illness during follow-up, particularly fever, rash, lymphadenopathy, or flu-like symptoms, as these may indicate acute retroviral syndrome 3, 1
• The patient remains at risk of transmitting HIV if infection occurred, even before antibodies are detectable 3

Additional Baseline Testing

• Screen for other sexually transmitted infections (gonorrhea, chlamydia, syphilis) at baseline using nucleic acid amplification tests 3, 1
• Test for hepatitis B surface antigen and hepatitis C antibody 3
• These infections may have been acquired during the same exposure event 3, 1

Common Pitfalls to Avoid

• Never rely solely on antibody-only tests in the early weeks post-exposure, as they will miss acute HIV infection 1, 4
• Do not stop testing at 6 weeks—the 12-week and 4-month timepoints are essential to capture delayed seroconversion 3, 2
• Do not assume a negative test at 4-6 weeks rules out infection; complete the full testing schedule 2

Special Consideration for Future Prevention

• If the patient has ongoing high-risk exposures, strongly consider transitioning to HIV pre-exposure prophylaxis (PrEP) after confirming HIV-negative status at the completion of testing 1, 2
• For patients with repeat exposures during the follow-up period, each new exposure may require PEP initiation if within 72 hours 3, 2