Epidemiological Characteristics of COVID-19: A Systemic Review and Meta-Analysis

Malahat Khalili; Mohammad Karamouzian; Naser Nasiri; Sara Javadi; Ali Mirzazadeh; Hamid Sharifi

For studies that did not provided enough data to be included in the meta-analysis, we 140 performed a qualitative data synthesis. Case-reports with a sample size of one were also 141 removed from the meta-analysis as they did not provide any dispersion estimate. Meta-142 analysis was performed using STATA's (V.15.1) metan (for numerical variables) and metaprop 143 (for binary variables) commands. The 95% confidence intervals (CI) for binary variables were 144 computed using the exact binomial method. Heterogeneity between studies was assessed 145 using both the I 2 statistic with a cutoff of ≥ 50% and the Chi-square test with P-value <0.10 to ICU admission, recovery and death. For mean incubation period, we estimated 99% CI. We 150 also conducted a random-effects meta-regression using STATA's metareg command to 151 identify the sources of heterogeneity and explore the effect of study-level covariates where 152 data were available. A two-sided P-value <0.05 was considered as statistically significant 153 effect. 154