SF case count now starting to look a little more clearly sigmoidal. I've been somewhat surprised that this hasn't flattened out more aggressively, now 15 days into shelter-in-place. Do we think that's due to testing backlog?
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Many helpful replies explaining the delay! Some plausible explanations:
- there's likely a several-day backlog for tests
- median pre-symptomatic time is 5 days but 97th %ile is 12 (!)
- hospitalized patients aren't necessarily tested on day 1
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Everyone needs to stop thinking COVID19 numbers today are today’s numbers. They’re not. They reflect: a) transmission between 12-18 days ago, b) onset and course of illness 7-14 days ago, c) hospitalization and testing, 7-1 days ago. Strictly: the present is the past.
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Hm. I thought the median incubation time was 5 days? But it’s a good point: people won’t necessarily go to the hospital at symptom onset, and the tests will take several more days. ncbi.nlm.nih.gov/pubmed/32150748
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Oh, interesting. My reading was that it was 5 days. ncbi.nlm.nih.gov/pubmed/32150748
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I think it's mainly because people don't generally get the really bad symptoms until the end of the 2nd week. That's when they're more likely to go get tested. A few more days and we'll see more flattening.
Also think compliance with the order has likely gotten better over time.
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This delayed flattening seems about what we should expect, given that symptoms appear up to 14 days after initial exposure? (Or maybe I'm misinterpreting what data the graph is showing?)
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(Unless SF is testing even asymptomatic people? I'm in NY, so our situation is a little different.)
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If it's 5 days incubation, you probably won't think about getting tested the first day, but maybe on day 2 or 3. Then it takes time to get an appointment. Then it takes time for the results to be determined. Then it takes time for the results to be officially reported.
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Also testing is getting ramped up. So if you had a very poor testing rate before initially and it has since been increase that, the number of *known* cases can still go up.
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