Estimating the Proportion of Asymptomatic COVID-19 Cases in an Italian Region with Intermediate Incidence during the First Pandemic Wave: An Observational Retrospective Study

Table 2

The proportion of asymptomatic SARS-CoV-2 infections reported in different systematic reviews and meta-analyses.

First author	Study period	Total SARS-CoV-2, no.	Asymptomatic SARS-CoV-2, no.	Pooled proportions
A. Kronbichlera et al. [16]	December 1, 2019 to March 29, 2020	NR	506	24.2% (SD 22.06)
J. Zhu et al. [17]	January 1 to February 28, 2020	3,062	158	11.9% (95% CI: 2.9-25.8%)
C. Chen et al. [18]	January 1 to May 13, 2020	20,152	NR	13.34% (95% CI: 10.86–16.29%)
J. He et al. [8]	Before May 20, 2020	50,155	1,430	15.6% (95% CI: 10.1-23.0%)
D. Buitrago-Garcia et al. [19]	March 25 to June 10, 2020	6,616	1,287	20% (95% CI: 17–25%)
M. Alene et al. [20]	June 1 to December 9, 2020	6,071	1,917	25% (95% CI: 16-38%)
P. Sah et al. [21]	January 1, 2020 to April 2, 2021	17,272	7,222	35.1% (95% CI: 30.7-39.9%)

NR: not reported. SD: standard deviation.