Although rapid antigen tests for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is convenient, some articles have demonstrated their low sensitivity indicating false-negative results should always be considered. Here, we raise the issue of false-positive on rapid antigen tests for SARS-CoV-2 with the first case of acute HIV infection who repeatedly positive for the rapid antigen test. A 39-year-old man was admitted to our hospital complaining of high-grade fever, dry cough, general fatigue, and anorexia. The rapid antigen test performed on a nasopharyngeal swab sample was positive, therefore the patient was separated in an isolated room apart from the COVID-19 ward while awaiting the confirmatory RT-PCR result. However, the RT-PCR for SARS-CoV-2 performed on nasopharyngeal swabs was repeatedly negative (three times), while the antigen test was repeatedly positive (three times in total). This patient was eventually diagnosed with acute human immunodeficiency virus (HIV) infection based on a high titer of HIV-RNA and absence of plasma HIV-1/2 antibodies. Physicians should consider the possibility of false-positive results in addition to false-negative results when using a rapid antigen test for SARS-CoV-2, and keep in mind that nucleic acid amplification tests are needed to confirm the diagnosis.
