ABSTRACT HIV infection remains a pervasive global health challenge, necessitating improved early diagnosis, swift access to care, and consistent monitoring for People Living with HIV (PLWH) to reduce new transmissions. However, a substantial gap persists in connecting and retaining individuals in the healthcare system, particularly in under-served regions. The analysis of blood CD4+ T cell numbers plays a central role in healthcare monitoring of PLWH, alongside measures of HIV load. To our knowledge, no commercially available home- based mail-in CD4 count tests exist. The development of such a test would alleviate barriers to HIV testing and monitoring, such as the need for travel to clinics and concerns about stigma, especially in underserved areas. Founded in Louisiana, a state grappling with a high incidence of new HIV cases, Spotted Tech is committed to addressing this challenge. The overarching goal is to improve HIV monitoring, healthcare management, and facilitate rapid linkage-to-care in underserved areas by reducing the need for clinic visits. The primary ob- jective of this proposal is to develop an innovative CD4 count test – the CD4-LINK Kit – where blood is self- collected in the form of a dried blood spot (DBS) on filter paper and mailed to a lab for CD4 count analysis. The central hypothesis is that the implementation of the CD4-LINK Kit in Louisiana will yield evidence of feasibility and usability for the health monitoring of PLWH. To test this hypothesis, three aims will be pursued: Aim 1 focuses on assay development, optimizing solutions allowing for optimal cell recovery from DBS, and assessing DBS sample stability under various storage and transportation conditions. Aim 2 involves in-house test validation to assess precision and accuracy. In Aim 3, field testing at four Louisiana HIV clinics will involve collecting finger stick blood samples and comparing their CD4 counts to those from fresh whole blood (gold standard). The CD4-LINK Kit is poised to stand out as the first-of-its-kind, addressing a notable gap in current testing ap- proaches; traditionally, CD4+ T cell absolute counts are accessible only through clinic visits. The underlying rationale for its development is to empower individuals to assess their CD4 counts from the comfort of their homes, alleviating the burden of travel for those in underserved areas. This innovation holds particular significance as it empowers people living with HIV (PLWH) to actively seek and maintain HIV care, thereby improving health, fostering early intervention, and ultimately contributing to a reduction in HIV transmission.

NARRATIVE HIV remains a global health challenge, necessitating strategies for timely diagnosis and rapid access to care for people living with HIV (PLWH) to curb new transmissions. Enrolling and retaining PLWH in care is particularly significant, yet challenging, in underserved regions with high infection rates. Spotted Tech is developing a home- based mail-in CD4 count test designed to alleviate the need for frequent clinic visits, empowering PLWH to proactively monitor their health status, facilitate early HIV intervention, and ultimately play a role in curbing the spread of HIV.