New analysis from @cmmid_lshtm (led by @timwrussell) provides some rough initial estimates for the % of symptomatic COVID-19 cases that might have been detected/reported in different countries (focusing on those with >10 deaths)... 1/ cmmid.github.io/topics/covid19… 
Our estimation works as follows: there's evidence the case fatality ratio should be 1–1.5% in populations with China-like age structure, so if (once we adjust for delays) we calculate a much higher CFR for a country, it suggests not all cases are being reported... 2/
Unsurprisingly, South Korea has high estimated % cases reported. Germany also has noticeably higher proportion than most, based on its low deaths:cases ratio. Among countries with >10 deaths, our estimates suggest around half have <10% of symptomatic cases being reported. 3/
Of course, countries have differing age-structure and health capacity, which means the baseline CFR won't be 1–1.5% in all of them. We're working to account for these differences, but in the meantime, this should give a rough idea of where we might be in terms of reporting. 4/
We're also assuming the delay from confirmation-to-death is similar across countries, and all COVID-19 deaths are reported, but this is likely to vary too - we'll update the estimates as more data become available. 5/
Finally, thanks to @ECDC_EU for making the underlying data publicly available 6/6
