By the Official Chinese Numbers: The Wuhan 2019-nCoV so Far

How to correctly calculate the mortality rate during an outbreak

The case fatality rate (CFR) represents the proportion of cases who eventually die from a disease.

Once an epidemic has ended, it is calculated with the formula: deaths/cases.

But while an epidemic is still ongoing, as it is the case with the current novel coronavirus outbreak, this formula is, at the very least, “naïve” and can be “misleading if, at the time of analysis, the outcome is unknown for a non-negligible proportion of patients.” [8](Methods for Estimating the Case Fatality Ratio for a Novel, Emerging Infectious Disease – Ghani et al, American Journal of Epidemiology).

Novel Coronavirus Mortality Rate, as discussed by the National Health Commission (NHC) of China

Asked at a press conference on February 4 what the current mortality rate (or case fatality rate, CFR) is, an official with China NHC said that [7]:

  • The formula they are using is: cumulative current total deaths/current confirmed cases. Therefore, as of 24:00 on Feb. 3, the formula used was 425/20,438.
  • Based on this figure, the national mortality rate to date was 2.1% of confirmed cases.
  • There might be mild cases and other cases not reported.
  • 97% of the country’s total deaths (414) were in the Hubei Province.
  • The mortality rate in Wuhan was 4.9%.
  • The mortality rate in Hubei Province was 3.1%.
  • Mortality rate nationwide was 2.1%.
  • The fatality rate in other provinces was 0.16%.
  • Deaths in Wuhan were 313, accounting for 74% of China’s total.
  • Most of the cases were still mild cases, therefore there was no need to panic.
  • Asked why Wuhan was so much higher than the national level, the NHC official replied that it was for lack of resources, citing as an example that there were only 110 critical care beds in the three designated hospitals where most of the cases were sent.
  • The national mortality rate was basically stable, as of Feb. 4 at 2.1%, and it was 2.3% at the beginning of the epidemic, which can be seen as a slight decline.
  • Front the analysis of death cases, it emerged that the demographic profile was mainly male, accounting for 2/3, females accounting for 1/3, and is mainly elderly, more than 80% are elderly over 60 years old, and more than 75% had underlying diseases present such as cardiovascular and cardiovascular diseases, diabetes and, in some cases, tumor.
  • Elderly people with basic diseases, as long as they have pneumonia, were clinically a high-risk factor regardless of whether it is a coronavirus or not, and the case fatality rate was also very high, so it is not that the case fatality rate of pneumonia is high because of the infection with the new coronavirus. “This point must be explained to everyone,” concluded the NHC official.[7]

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