Background Testing for SARS-CoV-2 using polymerase chain reaction (PCR) and SARS-CoV-2 antibody tests is a significant part of the effort to combat the COVID-19 pandemic. Mass testing of healthy individuals raises several issues, however, and the results can be challenging to interpret. Case presentation A healthy 19-year-old man entered the military after two weeks of quarantine. The recruit had no respiratory symptoms or fever before, during or after his enrolment, and no history of SARS-CoV-2 exposure. At enrolment, he had a positive rapid test and a venous blood sample showed antibodies against SARS-CoV-2. PCR tests of specimens obtained from the upper respiratory tract were negative at enrolment and at week three, but were positive at week six. Interpretation The overall assessment of all the tests indicates a probable asymptomatic infection. This case report illustrates the challenge of interpreting screening results in asymptomatic individuals.