Table 2.

HIV diagnostics in the context of AHI

Test	Advantages	Disadvantages	Cost (per test, USD)b
3rd generation antibody (POC)	ASSURED criteria: Affordable, sensitive, specific, user-friendly, rapid & robust, equipment free, delivered	Misses earliest phase of infection	1.5
4th generation antibody/antigen (EIA)	Detects infection earlier with p24 antigen sensitivity	Requires skilled personnel for specimen collection/laboratory processing Does not discriminate between antigen and antibody assay targets (i.e., acute and established HIV) without modified signal-to-cutoff ratiosŦ [72] Delayed result delivery increases risk of loss-to-follow-up Misses pre-p24 “eclipse” period May be prohibitively expensive for LMIC	5
4th generation (POC)	ASSURED criteria: Affordable, sensitive, specific, user-friendly, rapid & robust, equipment free, delivered Narrows window period for AHI diagnosis vs. 3rd generation	Poor field-performance to-date Misses pre-p24 “eclipse” period	Not available
Nucleic acid amplification testing (NAT) technologiesa	Highly sensitive, capable of diagnosing shortly after acquisition Pooling may decrease per-test costs in appropriate ratios	Requires skilled personnel for specimen collection/laboratory processing May be prohibitively expensive for LMIC; trade-off of increasing complexity with decreasing cost for pooling strategies Delayed result delivery increases risk of loss-to-follow-up	8–10
NAT technology (POC)	ASSURED criteria: Affordable, sensitive, specific, user-friendly, rapid & robust, equipment free, delivered Highly sensitive, capable of diagnosing shortly after acquisition	Early in development – in need of additional field testing Concern for throughput feasibility with current technologies Unknown cost	17–25

^awith and without pooling;

^ŦRamos et al. propose a modified testing algorithm through which reduced signal-to-cutoff ratios would trigger confirmatory Multispot and NAT testing to increase sensitivity of 4^th generation testing in detecting AHI. This ratio is determined using the signal strength of a sample compared to the signal strength of an internal cutoff with ratios ≥1.0 defined as positive by the manufacturer; LMIC – low- and middle-income countries; NAT – nucleic acid amplification testing; POC – point-of-care.

^bData from Cheryl Johnson, co-author.