“Since severe cases, which more likely lead to fatal outcomes, are detected at a higher percentage than mild cases, the reported death rates are likely inflated in most countries. Such under-estimation can be attributed to under-sampling of infection cases and results in systematic death rate estimation biases. The method proposed here utilizes a benchmark country (South Korea) and its reported death rates in combination with population demographics to correct the reported COVID-19 case numbers. By applying a correction, we predict that the number of cases is highly under-reported in most countries. In the case of China, it is estimated that more than 700.000 cases of COVID-19 actually occurred instead of the confirmed 80,932 cases as of 3/13/2020.”
also implying a lower CFR than previously thought (perhaps less than 0.5%). 3k deaths in China / 700k actual cases)
With testing capacities of 20,000 tests daily, it [South Korea] has the largest and most accurate coverage compared to all other countries as of writing. The low false-negative rate in detecting COVID-19 infections leads to the lowest death rate compared to all other countries (0.84) with major case count
Note that South Korea’s reported (naive) CFR is at >1% by now. It’s possible that the authors adjusted for the fact that most of South Korea’s cases were still active at the time of writing (about 55-60% of cases are still active now, I think), but I don’t see this in this paper. It probably doesn’t make a huge difference, but still relevant that this could cause the estimates to be a bit too low.
This method requires the comparison of two countries with sufficient confirmed cases and reported deaths. One country (target country) will be adjusted, given the information from the second country (benchmark country). In order to adjust for the difference in the population demographics of the target country, T, and the benchmark country, B, we compute a Vulnerability Factor (VTB).
Am I right that they’re not factoring in that patients had worse prospects in Wuhan than in South Korea? I feel like whatever the outcome of their adjustment process, that value would need to be multiplied by a factor >1 which represents hospital overstrain in Hubei, where at least 60% of China’s numbers stem from (probably more but I haven’t looked it up). I don’t know how large that adjustment should be exactly, but I find it weird that there’s no discussion of this. Am missing something about the methodology (maybe it factors in such differences automatically somehow)?
Ah, OK: They list this as an assumption:
[Assumption]Treatment has minor influence on outcome The provided healthcare in countries is comparable. For developed countries such as Italy and South Korea, it is assumed that the population has similar access to treatment. The death rates reported by age group are thus applicable in all countries
This is important to keep in mind when we try to derive implications from their estimate. Especially if we look at the hospitalization rates estimated here on page 5. For this disease in particular where people sometimes have to stay in hospitals for several weeks, it’s hard to imagine that treatment only makes a small difference.
And another preprint saying there were +700k cases in China on 13th of March:
“Since severe cases, which more likely lead to fatal outcomes, are detected at a higher percentage than mild cases, the reported death rates are likely inflated in most countries. Such under-estimation can be attributed to under-sampling of infection cases and results in systematic death rate estimation biases. The method proposed here utilizes a benchmark country (South Korea) and its reported death rates in combination with population demographics to correct the reported COVID-19 case numbers. By applying a correction, we predict that the number of cases is highly under-reported in most countries. In the case of China, it is estimated that more than 700.000 cases of COVID-19 actually occurred instead of the confirmed 80,932 cases as of 3/13/2020.”
also implying a lower CFR than previously thought (perhaps less than 0.5%). 3k deaths in China / 700k actual cases)
From the paper:
Note that South Korea’s reported (naive) CFR is at >1% by now. It’s possible that the authors adjusted for the fact that most of South Korea’s cases were still active at the time of writing (about 55-60% of cases are still active now, I think), but I don’t see this in this paper. It probably doesn’t make a huge difference, but still relevant that this could cause the estimates to be a bit too low.
From the paper:
Am I right that they’re not factoring in that patients had worse prospects in Wuhan than in South Korea? I feel like whatever the outcome of their adjustment process, that value would need to be multiplied by a factor >1 which represents hospital overstrain in Hubei, where at least 60% of China’s numbers stem from (probably more but I haven’t looked it up). I don’t know how large that adjustment should be exactly, but I find it weird that there’s no discussion of this. Am missing something about the methodology (maybe it factors in such differences automatically somehow)?
Ah, OK: They list this as an assumption:
This is important to keep in mind when we try to derive implications from their estimate. Especially if we look at the hospitalization rates estimated here on page 5. For this disease in particular where people sometimes have to stay in hospitals for several weeks, it’s hard to imagine that treatment only makes a small difference.