Case fatality rate of novel coronavirus disease 2019 in China

Rui Qi; Chao Ye; Xiang-rong Qin; Xue-Jie Yu

should be corrected as cases at T days before, where T is an average time period from case 67 confirmation to death. This study aims to calculate the CFR of the COVID-19 in China by 68 estimating the average time period from case confirmation to death. it should be realized that deaths at day X are averagely from cases at day X-T rather than day 75 X. Given a T value, a group of CFRs (daily CFRs) can be obtained from different X days. As 76 known that death number at day X should be less than case number at day X-T (if more than 77 day X-T, CFR would be greater than 100% which is illogical). Based on this point, the range 78 of T can be narrowed. More importantly, no matter what T value is assumed, even it is far 79 away from the true T value, the daily CFRs would converge towards (infinitely approach to 80 but never be over) the true CFR with time (X) increases. The following example will illustrate 81 this principle (Table 1) . Assuming CFR = 10%, T = 4 for a disease, the cases number was 82 from 100 to 10000 at day X (X=1 to 100), then the deaths number would be 10 (10, 20 and so 83 on) at day X+4 (5, 6 and so on). When calculating daily CFRs based on case and death 84 numbers with formula deaths (X) divided by cases (X-T), law 1: if assumed T was equal to 85 the true T value (4 in the example), calculated daily CFRs at different day X would constantly 86 be the true CFR (0.1); if assumed T was greater than the true T (5 and 6), daily CFRs would 87 be greater than the true CFR (0.1) and infinitely reduce to near it with the time (X) increased; 88 . CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.