A test for recent infection (TRI) measures maturation of HIV antibody avidity (i.e., antibody binding strength). Avidity increases after seroconversion, as part of the immune response, and the timing of this maturation varies among individuals. A rapid test for recent infection (RTRI) can help classify HIV-1 infections as recent or long-term using a simple lateral flow format. If antibody avidity has matured beyond a designated threshold by the time of testing, the RTRI classifies the sample as ‘long-term’. Otherwise, the result is ‘RTRI-recent’. Because long-term viral suppression (antiretroviral therapy [ART] or elite controllers) tends to lower antibody avidity, TRIs are not recommended to be used alone to classify HIV infections.