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HIV Diagnostic TestingQuestion 1/10

A 31-year-old man has a routine HIV screening test performed as part of a yearly primary care visit. The initial HIV-1/2 antigen-antibody immunoassay is positive, but a follow-up HIV-1/HIV-2 differentiation assay is negative for HIV-1 and HIV-2. In addition, an HIV-1 RNA assay is negative. He has no symptoms and has not had sex with anyone for at least 3 months. About 5 years ago he participated in an experiment HIV vaccine study. In addition, he had an influenza vaccine about 3 weeks ago. 

What is the most likely explanation for these test results?

Figure 1. CDC and APHL Recommended Laboratory Testing Algorithm for the Diagnosis of HIV Infection
Source:
1) Centers for Disease Control and Prevention and Association of Public Health Laboratories. Laboratory Testing for the Diagnosis of HIV Infection: Updated Recommendations. Published June 27, 2014.
(2) Centers for Disease Control and Prevention and Association of Public Health Laboratories. 2018 Quick reference guide: Recommended laboratory HIV testing algorithm for serum or plasma specimens. Published January 27, 2018.
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Question Last Updated
April 26th, 2026

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