Asymptomatic Patients as a Source of COVID-19 Infections: A Systematic Review and Meta-Analysis

Int J Infect Dis. 2020 Jun 17;S1201-9712(20)30487-2. doi: 10.1016/j.ijid.2020.06.052. Online ahead of print.


Background: Coronavirus Disease 2019 (COVID-19) is characterised by an unpredictable disease course, ranging from asymptomatic infections to severe, life-threating manifestations. Asymptomatic COVID-19 infections have been described, and the aim of this systematic review was to summarise their presentation form.

Methods: We searched PubMed® and Google® (1 December 2019 to 29 March 2020) and extracted age, laboratory findings, and computed tomography (CT) investigations. Pooled incidence rates of clinical characteristics were analysed using random effects models.

Results: In total, 506 patients from 34 studies (68 single cases and 438 from case series) with an asymptomatic course were identified. Patients with normal radiology were younger (19.59 ± 17.17 years) than patients with abnormal radiology (39.14 ± 26.70 years) (p value = 0.013). Despite being asymptomatic, CT investigations revealed abnormalities in 62.2% of the cases and ground glass opacities were most frequently observed (43.09% by meta-analysis). Most studies reported normal laboratory findings (61.74% by meta-analysis).

Conclusions: More than half of patients without any symptoms present with CT abnormalities. Asymptomatic patients may be contagious and thus a potential source of transmission of COVID-19.

Keywords: Asymptomatic; Coronavirus disease-19 (COVID-19); Meta-analysis; SARS-CoV-2.