A 51-year-old male presented for routine HIV screening, yielding a reactive fourth-generation HIV-1/2 antigen/antibody immunoassay. Subsequent differentiation immunoassay was negative for HIV-1 and indeterminate for HIV-2, while HIV-1 RNA PCR was undetectable. Further investigation revealed a history of recent influenza vaccination and autoimmune conditions, leading to suspicion of a false positive result. Repeated testing with a different immunoassay and HIV-1 RNA PCR remained negative, confirming the absence of HIV infection. This case highlights the importance of adhering to the CDC's HIV diagnostic algorithm to avoid misdiagnosis, especially when initial screening results are discordant with confirmatory tests.
Key note: Discordant HIV test results necessitate strict adherence to diagnostic algorithms to prevent misdiagnosis and patient distress.