Estimating Instant Fatality Rate of COVID-19 in China

Background: The outbreak of the coronavirus disease 2019 (COVID-19) in China has been basically controlled. However, the worldwide COVID-19 cases are increasing rapidly, showing a trend of global outbreak. Case fatality rate is the most direct indicator to assess the hazards of an infectious disease. We aimed to estimate the instant case fatality rate and cure rate of COVID-19 in China.Methods: We collected the accumulated data such as the numbers of daily confirmed/deaths/cured cases and the number of daily cumulative confirmed/deaths/cured cases released officially by Chinese authority from Dec 8, 2019 to Mar 15, 2020. Basing on the dates of diagnosis, deaths and discharge from individual cases, death time and cure time were calculated. And then the estimated diagnosis date of deaths and cured cases in the daily case notification data were calculated based on median cure time or median death time. Afterwards, according to the numbers of deaths and cured cases on the same estimated diagnosis dates the instant fatality rate was calculated.Findings: We collected 80860 confirmed cases of COVID-19, 13062 cases of them came from China except Hubei. In China the instant case fatality rate of COVID-19 was less than 10% (3.7-9.96%) from Jan 1 to Jan 15, 2020, continuously increased to 12% on Jan 19, and then gradually declined and stabilized at 4.4% on Feb 29. The instant case fatality rate tended to be stable at the end of February. The plateau was estimated at 4.2% at the end of March. The average case fatality rate in China was 7.4±3.1%%. In China except Hubei the case fatality rate was 0.5% to 3.4% from Feb 15 to Feb 29. Whereafter, the case fatality rate tended to be stable and less than 1%. The average case fatality rate was 1.1±0.6%. The instant cure rates of COVID-19 were 92.6%±3.1% in China, and the estimated one was 95.8%, while it was 98.9%±0.6% in China except Hubei.Interpretation: The instant case fatality rate of COVID-19 in China was much higher than that in China except Hubei. The instant cure rate in China except Hubei was higher than that in China. The fatality rate of COVID-19 in China was underestimated.Funding Statement: National Natural Science Foundation of China (No. 81803647and No. 81670001).Declaration of Interests: The authors declare no competing interests.