Diagnosis of COVID-19 pneumonia despite missing detection of viral nucleic acid and initially inconspicuous radiologic findings.

The diagnosis of coronavirus disease 2019 (COVID-19) is mainly based on a positive severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) polymerase chain reaction (PCR) result. PCR samples are obtained from upper or lower respiratory tract specimens. However, the sensitivity of PCR is known to have some limitations. We report on a patient who was admitted to our hospital with dyspnea, fever, cough, and history of contact with a SARS-CoV-2 infected relative. The initial chest computed tomography (CT) showed only minimal changes and SARS-CoV-2 PCR from a nasopharyngeal swab sample was negative. PCR results obtained from further nasopharyngeal swabs, qualified sputum samples, and from a lower respiratory tract specimen also remained negative. At day 13 after admission, a second chest CT showed radiological findings suspicious for viral pneumonia. Finally, serologic results showed high levels of immunoglobulin G and immunoglobulin A antibodies against the S1 domain of the SARS-CoV-2 spike protein, and the patient was diagnosed with COVID-19 pneumonia.