On January 29, 2020, a 43-year-old woman presented with a 4-day history of fever, cough, sputum production, and dyspnea. She had a recent history of travel to Wuhan (the center of the COVID-19 outbreak [formerly known as 2019 novel coronavirus]) with her 15-year-old son. Her temperature was 38°C (100.4°F) and she had coarse breath sounds on auscultation. Chest CT showed peripheral multifocal ground-glass opacities (Fig 1a). Her son also presented with prolonged fever (11 days), but without respiratory symptoms. On examination, his temperature was 39°C (102.2°F), and lungs were clear on auscultation. Chest CT showed centrilobular ground-glass nodules in the left lung (Fig 1b). The patient’s 43-year-old husband, who met the definition for a contact person (1), was asymptomatic on screening, but tested positive for COVID-19 on sputum real-time polymerase chain reaction test, as did the son and the wife. His chest CT was unremarkable (Fig1c), and he eventually developed fever on the following day.