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A considerable proportion of individuals with asymptomatic SARS-CoV-2 infection in Tibetan population

Our take —

Among a small group of Tibetan SARS-CoV-2 infected patients, asymptomatic presentation was common. However, the lack of key details regarding patient identification, presentation, and longitudinal symptomatology limits the impact of this publication.

Study design

Case Series

Study population and setting

18 individuals with laboratory-confirmed SARS-CoV-2 infection but no recorded symptoms were identified at a hospital in Daofu county, Sichuan, China. Most patients were identified between January 26, 2020 and February 28, 2020, and clinical data was included through March 6, 2020.

Summary of Main Findings

Among 83 inpatients with confirmed SARS-CoV-2 infection, 18 (22%) were identified as asymptomatic. The median age of asymptomatic cases was 31 years (range: 6-51), and only 1 (6%) had a diagnosed chronic comorbidity. 39% of asymptomatic patients had abnormalities on chest CT imaging, and 83% had an abnormal laboratory result.

Study Strengths



It is unclear how this patient group was identified, including why they were admitted to the hospital. As ascertainment of symptoms was based on retrospective review of medical records, it is uncertain whether i) these patients were truly asymptomatic, or simply did not have symptoms recorded and ii) the patients had non-respiratory symptoms. Given that 50% of patients appear to have received supplemental oxygen, there appears to have been at least some respiratory component to their presentation. Further, it is unclear whether these patients remained without symptoms throughout their entire hospital stay. There were no comparisons of clinical characteristics between asymptomatic and symptomatic patients, and the small sample size would limit such comparisons in any case.

Value added

This is one of the first studies to present descriptions of apparently asymptomatic patients with SARS-CoV-2 infection.