A 53-year-old woman presented during the SARS-CoV-2 pandemic with an 18-day history of pyrexia, myalgia, progressive dyspnoea and loss of taste and smell after a close contact had tested positive for SARS-CoV-2. In this period two swabs had been negative for SARS-CoV-2. Clinical examination was normal. During this admission a third SARS-CoV-2 swab was negative, and investigations showed mildly elevated inflammatory markers, mildly deranged liver function, atypical lymphocytes on a blood film and a normal chest x-ray. Her Epstein–Barr virus serology was positive and thus the diagnosis was infectious mononucleosis.