Step 1: HIV-1/2 Antigen/Antibody Immunoassay
- For initial HIV testing (aka “screening”), clinicians should use an HIV-1/2 Ag/Ab immunoassay (formerly known as the “4th-generation” test). (A2)
- For initial testing of newborns or individuals who are in labor, being evaluated for PEP, or unlikely to return for test results, clinicians should use an FDA-approved HIV screening test that provides results within 60 minutes (A2); otherwise, rapid tests are not recommended for step 1 of the standard HIV laboratory testing algorithm.
- Because all initial HIV tests are subject to false positive results, clinicians should consider all reactive initial test results preliminary and perform appropriate laboratory diagnostic testing to confirm a patient’s HIV status. (A1)
- Clinicians should educate patients about the limitations of in-home testing and emphasize that a laboratory should repeat both nonreactive and reactive results of any in-home HIV testing. (A3)
- In the case of a nonreactive result, the clinician should discuss goal-oriented, harm-reduction strategies, including PrEP and emergency PEP, with any patient who reports recent or likely ongoing HIV risk exposures or refer the patient for prevention services. (A3)
- Clinicians should offer repeat HIV testing every 3 months, or sooner if acute HIV is suspected, for as long as an individual remains at high risk of HIV exposure. (A3)
Step 2: HIV-1/HIV-2 Antibody Differentiation Immunoassay
- Per the standard HIV laboratory testing algorithm, if a reactive result is obtained with an HIV-1/2 Ag/Ab immunoassay test (step 1), clinicians should perform supplemental testing (step 2) with an FDA-approved HIV-1/HIV-2 Ab differentiation immunoassay. (A1)
- If the result of the HIV Ab differentiation immunoassay (step 2) is positive for HIV-1 or HIV-2 Abs, the clinician should provide or refer the patient for rapid ART initiation and transmission prevention counseling. (A1)
- Refer to the NYSDOH AI guideline When to Initiate ART, With Protocol for Rapid Initiation.
- Note: If the HIV Ab differentiation immunoassay result is positive but undifferentiated (i.e., reactive for both HIV-1 and HIV-2), repeat testing may determine if the patient has HIV-1 or HIV-2 infection.
Step 3: HIV-1 Nucleic Acid Testing (qualitative or quantitative HIV RNA testing)
- If the HIV-1/2 Ab differentiation immunoassay (step 2) result is nonreactive (negative) or indeterminate (neither positive nor negative for HIV-1 or HIV-2), and the lab does not perform reflex testing, the clinician should immediately order HIV-1 RNA NAT (step 3) to detect the presence of HIV-1 RNA and confirm or exclude HIV-1 infection. (A*)
- If HIV-1 RNA is detected, the clinician should inform the patient of the acute HIV-1 diagnosis, recommend ART initiation, and prioritize counseling to prevent HIV transmission. (A1)
- Clinicians should not wait for serologic confirmation of HIV to initiate ART when pregnant individuals are diagnosed with acute HIV infection by HIV-1 NAT; initiation of ART is strongly recommended for pregnant individuals. (A2)
- To determine the HIV status of an infant born to an individual with HIV-1, clinicians should perform HIV-1 RNA NAT. (A1)
