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About this publication
This version is outdated. The new version can be found here: COVID-19: Case fatality rate and infection fatality rate for serious COVID-19, 1st update – a rapid review
The findings in this memo are based on rapid searches in PubMed and LitCovid, as well as manual searches on websites. Two researchers shared tasks related to study selection and synthesis of results. In the current situation, there is an urgent need for identifying the most important evidence quickly. Hence, we opted for this rapid approach despite an inherent risk of overlooking key evidence or making misguided judgements.
Estimates of fatality rates for COVID-19
We selected data from across a range of surveillance studies and webpages, to obtain and overview at this point of time during the pandemic. From three countries we managed to find estimates of age-stratified case fatality ratio (China, Italy and South Korea). The age-stratified case fatality range is very similar for the younger age groups. For some additional countries we found the case fatality rate for the whole population. These numbers differ across sites, mainly because of the denominator populations in these datasets. Dividing the cumulative number of death by the cumulative reported case will underestimate the true fatality ratio, especially early in the growing epidemic. A recent study has correlated for censoring, demography and under-ascertainment to calculate an estimate case fatality rate of 1.38% (1.23-1.53) for China. They estimate age related case fatality rate for <60 years to be 0.318% (0.274-0.378), while for ages 60 years or older the CFR was 6.38% (5.70-7.17). The only data set that has accounted for a whole group that is tested is in the cruise ship Diamond Princess, with 10 deaths.
Factors that can explain the different data in fatality rates across countries
The overview of the case fatality rate in Italy compared to China shows that case fatality rate is higher in Italy than that observed in other countries and may be related to three factors: population age, definition of COVID-19 related death and testing strategies. In addition, the delay between testing and mortality in the numbers of early epidemic is a crucial bias. In a pandemic like COVID-19, even advanced health-care systems be overwhelmed by the increased hospitalisation, and will influence the case fatality rate in the near future.