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. 2020 Jun 22;192(25):E666-E670.
doi: 10.1503/cmaj.200711. Epub 2020 May 22.

Temporal estimates of case-fatality rate for COVID-19 outbreaks in Canada and the United States

Elaheh Abdollahi  1 , David Champredon  1 , Joanne M Langley  2 , Alison P Galvani  1 , Seyed M Moghadas  1
Affiliations

Temporal estimates of case-fatality rate for COVID-19 outbreaks in Canada and the United States

Elaheh Abdollahi et al. CMAJ. .

Abstract

Background: Estimates of the case-fatality rate (CFR) associated with coronavirus disease 2019 (COVID-19) vary widely in different population settings. We sought to estimate and compare the COVID-19 CFR in Canada and the United States while adjusting for 2 potential biases in crude CFR.

Methods: We used the daily incidence of confirmed COVID-19 cases and deaths in Canada and the US from Jan. 31 to Apr. 22, 2020. We applied a statistical method to minimize bias in the crude CFR by accounting for the survival interval as the lag time between disease onset and death, while considering reporting rates of COVID-19 cases less than 50% (95% confidence interval 10%-50%).

Results: Using data for confirmed cases in Canada, we estimated the crude CFR to be 4.9% on Apr. 22, 2020, and the adjusted CFR to be 5.5% (credible interval [CrI] 4.9%-6.4%). After we accounted for various reporting rates less than 50%, the adjusted CFR was estimated at 1.6% (CrI 0.7%-3.1%). The US crude CFR was estimated to be 5.4% on Apr. 20, 2020, with an adjusted CFR of 6.1% (CrI 5.4%-6.9%). With reporting rates of less than 50%, the adjusted CFR for the US was 1.78 (CrI 0.8%-3.6%).

Interpretation: Our estimates suggest that, if the reporting rate is less than 50%, the adjusted CFR of COVID-19 in Canada is likely to be less than 2%. The CFR estimates for the US were higher than those for Canada, but the adjusted CFR still remained below 2%. Quantification of case reporting can provide a more accurate measure of the virulence and disease burden of severe acute respiratory syndrome coronavirus 2.

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Conflict of interest statement

Competing interests: Joanne Langley holds the Canadian Institutes of Health Research- GlaxoSmithKline Chair in Pediatric Vaccinology at Dalhousie University. Dalhousie University has received funding for research studies from Sanofi Pasteur, Merck, Janssen, VBI and Pfizer. No other competing interests were declared.

Figures

Figure 1:
Figure 1:
(A) Daily incidence of coronavirus disease 2019 (bars) and associated deaths (black line) in Canada, 2020. (B) Crude case-fatality rate (CFR) (dashed line) and adjusted CFR estimates (red line) from Mar. 19 to Apr. 22, 2020. The shaded area around the red line illustrates the 95% credible interval for the adjusted CFR. Boxplots show the range of adjusted CFR estimates when the probability of reporting was less than 0.5 (95% confidence interval 0.1–0.5). Boxes indicate interquartile range (IQR), and lines indicate extended range from minimum (25th percentile − 1.5 IQR) to maximum (75th percentile + 1.5 IQR).
Figure 2:
Figure 2:
(A) Daily incidence of coronavirus disease 2019 (bars) and associated deaths (black line) in the United States, 2020. (B) Crude case-fatality rate (CFR) (dashed line) and adjusted CFR estimates (red line) from Feb. 28 to Apr. 20, 2020. The shaded area around the red line illustrates the 95% credible interval for the adjusted CFR. Boxplots show the range of adjusted CFR estimates when the probability of reporting was less than 0.5 (95% confidence interval 0.1–0.5). Boxes indicate interquartile range (IQR), and lines indicate extended range, from minimum (25th percentile − 1.5 IQR) to maximum (75th percentile + 1.5 IQR).
See this image and copyright information in PMC

References

    1. Wang X, Ma Z, Ning Y, et al. Estimating the case fatality ratio of the COVID-19 epidemic in China. medRxiv 2020. March 3. 10.1101/2020.02.17.20023630. - DOI
    1. Mizumoto K, Dahal S, Chowell G. Spatial variability in the risk of death from COVID-19 in Italy, 2020. medRxiv 2020. Apr. 16. 10.1101/2020.04.01.20049668. - DOI - PubMed
    1. Verity R, Okell LC, Dorigatti I, et al. Estimates of the severity of coronavirus disease 2019: a model-based analysis [published erratum in Lancet Infect Dis 2020 Apr. 15 [Epub ahead of print]. pii: S1473-3099(20)30309-1. doi: 10.1016/S1473-3099(20)30309-1; Lancet Infect Dis 2020. May 4 [Epub ahead of print]. pii S1473-3099 (20)30368-6. 10.1016/S1473-3099(20)30368-6]. - DOI - PMC - PubMed
    2. Lancet Infect Dis 2020. Mar. 30 [Epub ahead of print]. pii S1473-3099(20)30243-7. 10.1016/S1473-3099(20)30243-7. - DOI - PubMed
    1. Russell TW, Hellewell J, Jarvis CI, et al. Estimating the infection and case fatality ratio for coronavirus disease (COVID-19) using age-adjusted data from the outbreak on the Diamond Princess cruise ship. Euro Surveill 2020;25. 10.2807/1560-7917.ES.2020.25.12.2000256 - DOI - PMC - PubMed
    1. Garske T, Legrand J, Donnelly CA, et al. Assessing the severity of the novel influenza A/H1N1 pandemic. BMJ 2009;339:b2840. - PubMed