Table 1. Characteristics of COVID-19-related academic (PubMed) and preprint publications.
| Characteristic | PubMed N = 3635 No. (%) | Preprints N = 3805 No. (%) | Z value | % Difference | P value | |
|---|---|---|---|---|---|---|
| Species | Humans | 3507 (96.5) | 3634 (95.5) | 2.14 | 1.0 | <0.05 |
| Animals | 128 (3.5) | 93 (2.4) | 2.74 | 1.1 | <0.05 | |
| Publication type | Systematic review and/or meta-analysis | 29 (0.8) | 193 (5.0) | -10.83 | -4.2 | < 0.0001 |
| Randomized controlled trial | 8 (0.2) | 24 (0.6) | -2.71 | -0.4 | <0.05 | |
| Phase I | 1 | 0 | 1.02 | 1.0 | >0.05 | |
| Phase II | 3 | 3 | 0.06 | 0.0 | >0.05 | |
| Phase III | 0 | 2 | -1.38 | -2.0 | >0.05 | |
| Phase IV | 0 | 3 | -1.69 | -3.0 | >0.05 | |
| Protocols | 0 | 4 | -1.96 | -4.0 | >0.05 | |
| Epidemiologic studies | 222 (6.1) | 3522 (92.6) | -74.55 | -86.5 | < 0.0001 | |
| Observational studies | 21 (0.6) | 940 (24.7) | -31.02 | -24.1 | < 0.0001 | |
| Case report | 219 (6.0) | 35 (0.9) | 12.12 | 5.1 | < 0.0001 | |
| Letter to the Editor | 632 (17.4) | 19 (0.5) | 25.77 | 16.9 | < 0.0001 | |
| Research Area/Tag | Vaccine | 101 (2.8) | 114 (2.9) | -0.56 | -0.1 | >0.05 |
| Drug therapy | 57 (1.6) | 325 (8.5) | -13.62 | -6.9 | < 0.0001 | |
| Diagnosis | 781 (21.5) | 962 (25.3) | -3.87 | -3.8 | < 0.0001 | |
| Prevention and control (e.g., masks, social distancing) | 950 (26.1) | 1615 (42.4) | -14.80 | -16.3 | < 0.0001 | |
| Rehabilitation (e.g., pulmonary rehabilitation) | 23 (0.6) | 5 (0.1) | 3.53 | 0.5 | < 0.0001 | |
| Prognosis | 123 (3.4) | 844 (22.2) | -24.10 | -18.8 | < 0.0001 | |
| Biology/Genetic | 43 (1.1) | 866 (22.8) | -28.41 | -21.7 | < 0.0001 | |
Note: the sum of the characteristics does not correspond to the total number of publications since specifications or other may overlap.