The CT imaging demonstrates 5 stages according to the time of onset and the response of body to the virus, including: Ultra-early stage. This stage usually refers to the stage of patients without clinical manifestation, negative laboratory test but positive throat swab for 2019-nCoV within 1–2 weeks after being exposed to a virus-contaminated environment (history of contact with a patient or patient-related family members, unit, or medical staff in a cluster environment). The main imaging manifestations are single, double or scattered focal ground-glass opacity, nodules located in central lobule surrounded by patchy ground-glass opacities, patchy consolidation and sign of intra-bronchial air-bronchogram, which was dominant in the middle and lower pleura (Fig. 6: 7 cases, 8.4% in a total of 83 cases).
Fig. 6 CT imaging of ultra-early stage. a A 33 years old female with patchy ground-glass opacities after occupational exposure. b A 67 years old male with a history of contact with infected patients, showing large ground-glass opacity. c A 35 years old female exhibiting large consolidated opacity with air-bronchogram inside after occupational exposure