Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
Meta-Analysis
. 2020 Sep:98:180-186.
doi: 10.1016/j.ijid.2020.06.052. Epub 2020 Jun 17.

Asymptomatic patients as a source of COVID-19 infections: A systematic review and meta-analysis

Andreas Kronbichler  1 , Daniela Kresse  2 , Sojung Yoon  3 , Keum Hwa Lee  4 , Maria Effenberger  5 , Jae Il Shin  6
Affiliations
Meta-Analysis

Asymptomatic patients as a source of COVID-19 infections: A systematic review and meta-analysis

Andreas Kronbichler et al. Int J Infect Dis. 2020 Sep.

Abstract

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

Methods: We searched PubMed® and Google® (1 December 2019 to 29 March 2020) and extracted age, laboratory findings, and computed tomography (CT) scans. Pooled incidence rates of clinical characteristics were analyzed using random-effect 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; 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 the 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.

PubMed Disclaimer

Figures

Fig. 1
Fig. 1
PRISMA flow diagram for literature search.
Fig. 2
Fig. 2
Meta-analyses on the proportion of radiologic findings in asymptomatic patients.
Fig. 3
Fig. 3
Meta-analyses on the proportion of laboratory findings in asymptomatic patients.
See this image and copyright information in PMC

Similar articles

See all similar articles

Cited by

See all "Cited by" articles

References

    1. Bai Y., Yao L., Wei T., Tian F., Jin D.Y., Chen L. Presumed asymptomatic carrier transmission of COVID-19. JAMA. 2020 - PMC - PubMed
    1. Chen N., Zhou M., Dong X., Qu J., Gong F., Han Y. Epidemiological and clinical characteristics of 99 cases of 2019 novel coronavirus pneumonia in Wuhan, China: a descriptive study. Lancet. 2020;395(10223):507–513. - PMC - PubMed
    1. DerSimonian R., Kacker R. Random-effects model for meta-analysis of clinical trials: an update. Contemp. Clin. Trials. 2007;28(2):105–114. - PubMed
    1. Fletcher J. What is heterogeneity and is it important? BMJ. 2007;334(7584):94–96. - PMC - PubMed
    1. Guan W.J., Ni Z.Y., Hu Y., Liang W.H., Ou C.Q., He J.X. Clinical characteristics of coronavirus disease 2019 in China. N. Engl. J. Med. 2020 - PMC - PubMed