A 63-year-old Chinese man from Wuhan, China, presented to the emergency department of Princess Margaret Hospital, Hong Kong, in January 2020 with coryzal symptoms.

He was afebrile with unremarkable respiratory examination results. He was admitted to an isolation ward for further investigation. He subsequently developed a fluctuating fever up to 38.5°C after admission and passed loose stool intermittently. His oxygen saturation levels were normal throughout hospitalisation. Supportive treatment and empirical antibiotics (amoxicillin-clavulanate) were administered.

Coronavirus disease 2019 (COVID-19) was suspected, and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection was confirmed the next day by throat swab and nasopharyngeal aspirate tests. Stool culture was negative for SARS-CoV-2 and other pathogens.

Blood test results revealed lymphopoenia (0.6 × 109/L). Total white blood cell count (4.4 × 10⁹/L), absolute neutrophil count (3.4 × 10⁹/L), monocyte count (0.3 × 10⁹/L), and eosinophil count (0.0 × 10⁹/L) were normal. Liver and renal function test results, C-reactive protein level, and serum calcium and phosphate levels were normal.

Daily portable chest radiographs over the next 5 days were unremarkable (Fig 1). Chest high-resolution computed tomography (HRCT) was performed to assess for pulmonary involvement. High-resolution computed tomography performed 6 days after admission (Fig 2) demonstrated a few patchy subpleural ground-glass opacities in both lungs. No other abnormalities were detected. Subsequent follow-up chest radiograph (Fig 3) remained clear.

The patient’s fever subsided 11 days after admission. No supplemental oxygen was required. Serial nasopharyngeal aspirate sample tests turned negative 22 days after admission. The patient was discharged from the hospital 27 days after admission.

The SARS-CoV-2 infection is diagnosed with reverse transcription polymerase chain reaction results of respiratory specimens.

Prior to availability of confirmatory microbiological test results, challenges exist in decision making for patients with suspected COVID-19.

We advocate that early HRCT should be considered in suspected cases to aid in clinico-radiological diagnosis of SARS-CoV-2 infection by demonstrating compatible radiological features, before microbiological confirmation has been established.

This can be especially beneficial if patients have negative preliminary virology or radiographic findings, as in the previously reported HRCT features in severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS),1 2 as well as recent reports on COVID-19 from China3 and Hong Kong.4

Findings on serial chest radiographs before and after HRCT remain occult without demonstrable airspace opacity, limiting its value in initial assessment, monitoring or exclusion of pulmonary involvement.

This is consistent with experience during the SARS epidemic that HRCT was useful for early radiological assessment for patients with negative chest radiographs.5

Our patient subsequently demonstrated a favourable outcome with recovery and did not require supplemental oxygen throughout hospitalisation.

Mirroring experiences in previous coronavirus outbreaks such as SARS and MERS, we believe that HRCT will likely play a key role in aiding diagnosis, assessing the extent of pulmonary involvement and risk in the current COVID-19 pandemic. Early HRCT can be beneficial in patients with obscure clinical presentation or negative preliminary virological or radiographic findings.

All authors contributed to the concept or design of the study, acquisition of the data, drafting of the manuscript, and critical revision of the manuscript for important intellectual content. All authors had full access to the data, contributed to the study, approved the final version for publication, and take responsibility for its accuracy and integrity.

All authors have disclosed no conflicts of interest.

We would like to express our gratitude to the Infectious Disease Team and “dirty team” physicians of Princess Margaret Hospital, Hong Kong, for their professional patient care and invaluable contribution to the understanding of a novel disease.

This pictorial medicine paper received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.

This study was approved by the Kowloon West Cluster Research Ethics Committee (Ref KW/EX-20-049(145-08)).

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3. Lei J, Li J, Li X, Qi X. CT imaging of the 2019 novel coronavirus (2019-nCoV) pneumonia. Radiology 2020;295:18. Crossref

4. World Health Organization. Clinical management of severe acute respiratory infection when COVID-19 is suspected. Interim guidance. Available from: https:// www.who.int/publications-detail/clinical-management-of-severe-acute-respiratory-infection-when-novel-coronavirus-(ncov)-infection-is-suspected. Accessed 6 Feb 2020.

5. Hui JY, Hon TY, Yang MK, et al. High-resolution computed tomography is useful for early diagnosis of severe acute respiratory syndrome-associated coronavirus pneumonia in patients with normal chest radiographs. J Comput Assist Tomogr 2004;28:1-9. Crossref