IntroductionHIV assays designed to detect recent infection, also known as “recency assays,” are often used to estimate HIV incidence in a specific country, region, or subpopulation, alone or as part of recent infection testing algorithms (RITAs). Recently, many countries and organizations have become interested in using recency assays within case surveillance systems and routine HIV testing services, and in measuring other indicators beyond incidence, generally referred to as “non-incidence surveillance use cases.”MethodsTo identify best methodological and field implementation practices for the use of recency assays to estimate HIV incidence and trends in recent infections for key populations or specific geographic areas, we undertook: 1) a global Call for Information released from WHO/UNAIDS; and 2) a systematic review of the literature to: (a) assess the field performance characteristics of commercially available recency assays, (b) understand the use of recency testing for surveillance in programmatic and laboratory settings, and (c) review methodologies for implementing recency testing for both incidence estimation and non-incidence use cases.Results and discussionAmong the 90 documents ultimately reviewed, 65 (88%) focused on assay/algorithm performance or methodological descriptions, with high-quality evidence of accurate age- and sex- disaggregated HIV incidence estimation at national or regional levels in general population settings, but not at finer geographic levels for prevention prioritization. The remaining 25 documents described field-derived incidence (n=14) and non-incidence (n=11) use cases, including integrating RITAs into routine surveillance and assisting with molecular genetic analyses, but evidence was generally weaker or only reported on what was done, without validation data or findings related to effectiveness of recency assays when used for these purposes.ConclusionsHIV recency assays have been widely validated for estimating HIV incidence in age- and sex-specific populations at national and sub-national regional levels; however, there was a lack of evidence validating the accuracy and effectiveness of using recency assays for non-incidence surveillance use cases. The evidence identified through this review will be used in forthcoming technical guidance on the use of HIV recency assays for surveillance use cases by WHO and UNAIDS; further evidence on methodologies and effectiveness of non-incidence use cases is needed.