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Some #COVID19 rates: their meanings and implications (very roughly). Thread.
- recovery rate
- case fatality rate
- infection fatality rate
- mortality rate
- test positivity rate
- case detection rate
- recovery rate
- case fatality rate
- infection fatality rate
- mortality rate
- test positivity rate
- case detection rate
Recovery rate: % of recorded cases who have recovered. Starts very low at the beginning of a pandemic (no one recovered yet). Remains low during rapid growth. Rises as the pandemic slows and ends high. India at 38.73% is still quite early in this story... https://scroll.in/latest/962325/covid-19-states-announce-own-rules-during-lockdown-4-0-most-permit-public-transport">https://scroll.in/latest/96...
Case fatality rate: percentage of total recorded cases who have died. Treat with caution. If you& #39;re testing widely you lower the CFR - good. If you& #39;re under-reporting COVID deaths you also lower the CFR - hmmm. https://twitter.com/muradbanaji/status/1262719734522544131">https://twitter.com/muradbana...
Infection fatality rate (IFR): percentage of total cases who will die. This is the fatality rate we do really want to know. Should vary according to age structure of a country, levels of general health, access to healthcare, etc. Perhaps I& #39;ll do a thread on IFR estimates.
Mortality rate: that& #39;s the total number of people who die, say, per million population. At the end of an epidemic that& #39;s one number you want to look at to see how bad it& #39;s been. In the early stages of an epidemic: it& #39;s pretty meaningless.
Test positivity rate: % of total tests which are positive. Tells you if you& #39;re testing people with a high probability of having the infection. Used as a proxy for disease prevalence, but low numbers could just mean that you& #39;re testing the wrong people. https://twitter.com/muradbanaji/status/1256256032541601797">https://twitter.com/muradbana...
Case detection rate: the percentage of total infections being picked up in testing. We *do* want to know this, but it& #39;s hard to estimate - you need the true total infections i.e., "prevalence". Estimating prevalence requires either surveying (e.g., serosurveying), or modelling.
