Table 1.
General summary of included citations.
| References | Country | Study Type ** | Number of Patients/Studies * (COVID-19 vs. Influenza) |
|---|---|---|---|
| Jordan Cates et al. [6] | United States | Cohort | 9401 (3948 vs. 5453) |
| Ying Luo et al. [7] | China (Hubei) | Cohort | 2167 (1027 vs. 1140) |
| Jiangnan Chen et al. [8] | China (Shaoxing) | Case-Control | 380 (169 vs. 131; 80 healthy controls) |
| Jiajia Qu et al. [9] | China | Retrospective Cohort | 366 (246 vs. 120) |
| Jianguo Zhang et al. [10] | China | Retrospective cohort | 326 (211 vs. 115) |
| Helene Faury et al. [11] | France (Paris) | Retrospective | 200 (100 vs. 100) |
| Pengfei Li et al. * [5] | - | Systematic review and Meta-analysis | 197 (113 vs. 84) |
| Mengqi Liu et al. [12] | China (Chongqing) | Retrospective | 180 (122 vs. 48) |
| Xiao Tang et al. [13] | China (Wuhan) | Retrospective case-control | 148 (73 vs. 75) |
| Natalie L. Cobb et al. [14] | United States (Washington) | Retrospective Cohort | 139 (65 vs. 74) |
| Souheil Zayet et al. [15] | France | Retrospective | 124 (70 vs. 54) |
| Hao Wang et al. [16] | China | Retrospective | 105 (13 vs. 92) |
| Liaoyi Lin et al. [17] | China (Wenzhou) | Retrospective | 97 (52 vs. 45) |
| Raija Auvinen et al. [18] | Finland | Prospective study | 61 (28 vs. 33) |
| Zhilan Yin et al. [19] | China | Retrospective | 60 (30 vs. 30) |
| Yi-Hua Lin et al. [20] | China (Xiamen) | A cross-sectional retrospective study | 57 (35 vs. 22) |
| Jaehee Lee et al. [21] | South Korea (Daegu) | Retrospective | 29 (20 vs. 09) |
| Stephen O. Onigbinde et al. * [3] | - | Review | 17 (09 vs. 08) |
* Studies for Review or Meta-analysis. ** Cohort studies are used to investigate causes of disease and establish association between risk factors and health outcomes. An outcome-free study population is first identified by the exposure/event of interest and followed in time until the outcome of interest happens. They can be prospective (carried out from the present time into the future) or retrospective (carried out at the present time and look to the past to examine medical events or outcome). Case-Control studies first identify subjects by outcome status (cases), then select from the same source population, subjects without the outcome (control). Cross-sectional study or prevalence study is an observational study that collects data on the subjects of interest at a specific point in time.