I agree that’s the critical question. One possibility that seems reasonably likely to me (based on aïve SIR math) is that we wait until ICUs are overflowing and that’s too late for interventions to make a difference.
This isn’t compatible with what we saw in India/UK, though. 🤷♂️
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I’m not sure too late to make a difference would mean? It could mean ICUs are still overwhelmed for a while, but unless population immunity is high, why wouldn’t measures make some difference?
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Here’s how I’d see that happening: suppose that we’re pretty far into a big exponential wave. By the time the ICUs fill up (30/100k in ICU), that means that, say, 3000/100k = 3% have covid (at 1% chance of needing ICU given infection).
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Assume it takes two weeks to need an ICU bed from infection. At Delta growth rates (doubling roughly weekly or so?) that means you could end up with a peak load of >10% already “locked in” if you wait until ICUs are full to act.
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I actually don’t think that can happen in many places (like the US northeast) because they’re less than 10% of the population with immunity (via infection or vaccination) away from herd immunity. But you can still overwhelm ICUs.
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Yeah, I definitely agree ICUs can get overwhelmed. Is that true in the NE even though vaccines aren’t providing excellent sterilizing immunity against delta?
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I’m very uncertain one this. My current best guess is that there is enough sterilizing immunity from vaccines to make most vaccinated people a rounding error as *sources* of covid infection at a society level. If that’s true, this conclusion holds.
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One interesting point that supports this: my home province of Ontario has high Delta prevalence but has seen a much more moderate increase in cases compared to the Northeast, with only slightly higher vaccination rates (<10% difference).
They have kept more NPIs, though.
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Any chance you can share where you found the data regarding Ontario and prevalence of Delta specific cases? I’ve been unable to find that. Thanks!
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I've been following these stats: covid19-sciencetable.ca/ontario-dashbo
As far as I can tell this is from some kind of government advisory group.
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They aren't super clear on where those numbers come from; my best guess is it's from "Public Health Case and Contact Management Solution and other case management systems (CCM plus)", which sounds like it isn't public.🤷♂️