This study proposes to investigate the performance of existing and new technologies for HIV diagnosis, one of the key strategies for Ending the HIV Epidemic in the U.S. Current, Standard-of-Care (SOC) diagnostic techniques have extended turn-around-times (TATs) that result in loss of patients to follow up due to delays in laboratory procedures. In this scenario, patients that are at a high-risk for HIV have the potential to continue transmission, making it difficult to end the epidemic. Rapid, Point-of-Care (POC) HIV viral load (VL) testing alleviates this problem by reducing TATs that allow providers to test for HIV infection and link patients to antiretroviral therapy (ART) or pre-exposure prophylaxis (PrEP) during the same clinical visit, and subsequently, suppress VL, prevent HIV infection, and reduce its transmission among high-risk populations. The study proposes that evaluating the performance of new and existing POC technologies is needed to provide updated information to HIV test providers operating in different populations and settings and improve linkage to HIV treatment and prevention services. The study hypothesizes that:

A. Determining the performance characteristics of HIV POC tests will inform optimal testing strategies in different populations and settings

B. The use of HIV RNA POC tests will improve linkage to HIV treatment and prevention services:

i. Improve early diagnosis of HIV ii. Reduce the time to ART initiation iii. Facilitate timely and appropriate referral for prevention services

The strategy for Ending the HIV Epidemic (EHE) includes four key strategies that together can end the HIV epidemic in the United States (US): Diagnose, Treat, Prevent, and Respond. Diagnosis is the gateway to all other interventions; it is the cornerstone of EHE. In 2019/20 it was estimated that more than 160,000 Americans are unaware of living with HIV. Early diagnosis coupled with rapid linkage to care is critical and can lead to improved individual and community health outcomes. Achieving this goal will require improved, more accessible, and routine HIV testing; immediately connecting people with HIV to care services; and connecting those without HIV to appropriate HIV prevention services. Maryland was ranked 6th among states and territories in adult/adolescent HIV diagnosis rates (per 100,000) in 2018, tied with Mississippi. Among people living with HIV in Maryland in 2019, the Centers for Disease Control and Prevention (CDC) estimated that 89.2% had been diagnosed and that ~3,830 people with HIV are undiagnosed.

Evaluation of existing and new POC HIV tests is needed to inform testing guidelines and provide updated information to HIV test providers. Characterizing the performance of POC tests can provide estimates for the window period for HIV detection (i.e., the time from HIV acquisition to the time that a diagnostic test becomes positive). The window period provides key information needed to interpret an initial positive test result and assess the risk of transmission to others. It may also help guide decisions about repeat testing and initiation of ART in those with HIV and prevention interventions, including PrEP and post-exposure prophylaxis (PEP) (in those without HIV).

During the window period for an HIV Antigen/Antibody (Ag/Ab) test, infected individuals may have non-reactive test results, falsely reassuring patients and providers. HIV RNA [or 'viral load' (VL)] assays have window periods that are approximately 10 days shorter than most HIV Ag/Ab tests, providing greater sensitivity for detection of early HIV infection. The use of HIV RNA detection platforms for HIV screening facilitates earlier diagnosis and more effective implementation of ART and PrEP. This may be especially useful in settings where the infection is acquired in persons using PrEP, since PrEP agents may suppress viral replication and delay antibody production.

The following hypotheses underpin the planned study:

A. Determining the performance characteristics of HIV POC tests will inform optimal testing strategies in different populations and settings.

B. Use of HIV RNA POC tests will improve linkage to HIV treatment and prevention services.

The implications of this CDC-sponsored research are important since this research could improve early diagnosis of HIV, reduce the time to ART initiation, and facilitate timely and appropriate referral for prevention services. Additionally, if someone is infected while using long-acting PrEP, or initiated PrEP while infected, the risk of resistance and side effects can be minimized; if the infection is missed. These are critical issues for EHE success.

Inclusion Criteria:

• Aged 18 years or older
• Living with or at high risk for HIV (MSM/transgender; injection drug use (IDU); known STI or being screened for STI; part of a high STI prevalence network [e.g., in the Sexual Health clinic])
• Willing to undergo phlebotomy and collection of oral fluid samples
• Willing to complete a questionnaire
• Willing to have laboratory results shared with the clinician(s) associated with their care
• Willing to attend follow-up visits
• Willing for samples to be transferred to the CDC for analysis and storage

Exclusion Criteria:

• Aged <18 years
• Unwilling to undergo study procedures
• Any other reason deemed pertinent by the study team

From enrollment unitl end of follow-up, up to 12 weeks