What is the next step for a patient with a positive HIV (Human Immunodeficiency Virus) 1/2 antibody test result?

Next Step After Positive HIV1/2 Antibody Test

The next step is to perform confirmatory testing with an HIV-1 Western blot or indirect immunofluorescence assay to establish a definitive diagnosis before initiating any treatment or counseling the patient as HIV-infected. 1

Confirmatory Testing Algorithm

Primary Confirmatory Test

• Order HIV-1 Western blot or indirect immunofluorescence assay immediately to confirm the positive screening result 1, 2
• Do not diagnose HIV infection or initiate treatment based solely on the positive screening antibody test 2
• All positive screening tests must be confirmed before establishing a definitive HIV diagnosis 2, 3

Interpretation Based on Western Blot Results

If HIV-1 Western blot is POSITIVE:

• Consider the patient HIV-infected and counsel/manage as HIV-1 infection 1, 3
• No further testing is required for routine clinical purposes 3
• Consider retesting with a second specimen to confirm the initial positive result 1, 3
• If the patient has epidemiologic risk factors for HIV-2 (e.g., from West Africa, sexual contact with someone from endemic areas), perform additional HIV-2 testing even with positive HIV-1 Western blot 1, 3

If HIV-1 Western blot is NEGATIVE:

• Perform HIV-2 EIA testing 1
• If HIV-2 EIA is NOT repeatedly reactive: inform the patient that test results are negative for HIV infection 1, 2
• If HIV-2 EIA IS repeatedly reactive: proceed to HIV-2 supplemental testing (send to state public health laboratory) 1

If HIV-1 Western blot is INDETERMINATE:

• Perform HIV-2 EIA testing 1
• If HIV-2 EIA is repeatedly reactive, send for HIV-2 supplemental testing 1
• If HIV-2 supplemental test is negative, follow the patient with repeat testing 1
• If HIV-2 supplemental test is indeterminate, perform follow-up testing at 6 months to exclude early HIV-1 or HIV-2 infection 1
• Perform follow-up testing on a blood specimen collected 4 weeks after the initial reactive test 1

Special Considerations for Acute Infection

• If acute HIV infection is suspected (high-risk exposure within past 4-6 weeks, symptoms consistent with acute retroviral syndrome), order HIV-1 RNA assay (nucleic acid test) to exclude window period infection when antibody tests may still be negative 2, 4, 5
• The window period for antibody detection is typically the first 3-4 weeks after infection 3
• Fourth-generation immunoassays that detect p24 antigen can identify infections earlier than antibody-only tests 5

Critical Clinical Pitfalls to Avoid

• Never initiate HIV treatment until infection has been documented with confirmatory testing 2
• Do not counsel a patient as HIV-2 infected based solely on a repeatedly reactive HIV-2 EIA without supplemental testing 1
• In the United States, the vast majority of specimens with repeatedly reactive HIV-2 EIA and negative/indeterminate HIV-1 Western blot represent false-positive results in the absence of epidemiologic risk factors for HIV-2 1
• Be aware that some oral rapid tests have higher false-positive rates; consider confirming positive oral rapid tests with whole blood rapid testing 1

Exception: Pregnant Women in Labor

• Pregnant women with preliminary positive HIV test results should receive antiretroviral prophylaxis during labor without waiting for confirmatory results to prevent perinatal transmission 1, 2
• If confirmatory testing is negative, stop prophylaxis and breastfeeding may be initiated 2
• This is the only clinical scenario where action should be taken before confirmatory testing is complete 1

Counseling During the Confirmation Period

• Counsel on risk reduction measures during the follow-up period regardless of initial interpretation 2
• Explain that the positive screening test is "preliminary positive" and requires confirmation 1
• Avoid definitive statements about HIV status until confirmatory testing is complete 1, 2