Estimates of the severity of COVID-19 disease

  1. Robert Verity
  2. Lucy C Okell
  3. Ilaria Dorigatti
  4. Peter Winskill
  5. Charles Whittaker
  6. Natsuko Imai
  7. Gina Cuomo-Dannenburg
  8. Hayley Thompson
  9. Patrick GT Walker
  10. Han Fu
  11. Amy Dighe
  12. Jamie T Griffin
  13. Marc Baguelin
  14. Sangeeta Bhatia
  15. Adhiratha Boonyasiri
  16. Anne Cori
  17. Zulma Cucunubá
  18. Rich FitzJohn
  19. Katy Gaythorpe
  20. Will Green
  21. Arran Hamlet
  22. Wes Hinsley
  23. Daniel Laydon
  24. Gemma Nedjati-Gilani
  25. Steven Riley
  26. Sabine van Elsland
  27. Erik Volz
  28. Haowei Wang
  29. Yuanrong Wang
  30. Xiaoyue Xi
  31. Christl A Donnelly
  32. Azra C Ghani
  33. Neil M Ferguson

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Abstract

Background

A range of case fatality ratio (CFR) estimates for COVID-19 have been produced that differ substantially in magnitude.

Methods

We used individual-case data from mainland China and cases detected outside mainland China to estimate the time between onset of symptoms and outcome (death or discharge from hospital). We next obtained age-stratified estimates of the CFR by relating the aggregate distribution of cases by dates of onset to the observed cumulative deaths in China, assuming a constant attack rate by age and adjusting for the demography of the population, and age- and location-based under-ascertainment. We additionally estimated the CFR from individual line-list data on 1,334 cases identified outside mainland China. We used data on the PCR prevalence in international residents repatriated from China at the end of January 2020 to obtain age-stratified estimates of the infection fatality ratio (IFR). Using data on age-stratified severity in a subset of 3,665 cases from China, we estimated the proportion of infections that will likely require hospitalisation.

Findings

We estimate the mean duration from onset-of-symptoms to death to be 17.8 days (95% credible interval, crI 16.9–19.2 days) and from onset-of-symptoms to hospital discharge to be 22.6 days (95% crI 21.1-24.4 days). We estimate a crude CFR of 3.67% (95% crI 3.56%-3.80%) in cases from mainland China. Adjusting for demography and under-ascertainment of milder cases in Wuhan relative to the rest of China, we obtain a best estimate of the CFR in China of 1.38% (95% crI 1.23%-1.53%) with substantially higher values in older ages. Our estimate of the CFR from international cases stratified by age (under 60 / 60 and above) are consistent with these estimates from China. We obtain an overall IFR estimate for China of 0.66% (0.39%-1.33%), again with an increasing profile with age.

Interpretation

These early estimates give an indication of the fatality ratio across the spectrum of COVID-19 disease and demonstrate a strong age-gradient in risk.

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  1. ScreenIT

    SciScore for 10.1101/2020.03.09.20033357: (What is this?)

    Please note, not all rigor criteria are appropriate for all manuscripts.

    Table 1: Rigor

    Institutional Review Board Statementnot detected.
    Randomizationnot detected.
    Blindingnot detected.
    Power Analysisnot detected.
    Sex as a biological variablenot detected.

    Table 2: Resources

    No key resources detected.

    Results from OddPub: Thank you for sharing your code and data.

    Results from LimitationRecognizer: An explicit section about the limitations of the techniques employed in this study was not found. We encourage authors to address study limitations.

    Results from TrialIdentifier: No clinical trial numbers were referenced.

    Results from Barzooka: We did not find any issues relating to the usage of bar graphs.

    Results from JetFighter: We did not find any issues relating to colormaps.

    Results from rtransparent:
    • Thank you for including a conflict of interest statement. Authors are encouraged to include this statement when submitting to a journal.
    • Thank you for including a funding statement. Authors are encouraged to include this statement when submitting to a journal.
    • No protocol registration statement was detected.

    About SciScore

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  2. Version published to 10.1101/2020.03.09.20033357v1 on medRxiv