[burger]

One thing that would result in an earlier peak is social distancing measures. Another is if prevalence is much higher than we expect. Say instead of unmeasured cases being 10x, they are actually 20 or 30x of measured cases. This means its spreading faster than initial models predicted, and so peak will be sooner. Also total deaths lower.

I suspect both of these are true to some extent.

Perhaps, although there's no universe where the prevalence rates are approaching where more have been exposed/infected than have not. Indeed, the best modeling I've seen done recently suggests the highest rates of infection are in Italy (est. of 9.8%) and Spain (15%). Even the worst (best?) case scenario estimates for prevalence in Italy are ~1/4 of the population infected. That is a long way off from herd immunity formation:

[tweet]https://twitter.com/joshmich/status/1244645729664106497?s=20[/tweet]

These Imperial College models are full of shit.  They can only get those giant numbers of infected people (the %s are small, but the numbers imply millions infected in each country) if they assume a giant number of asymptomatic or very mild infections--like 10+ asymptomatics for every symptomatic.  Data from places with heavy testing, like the Diamond Princess, suggest a much lower rate of asymptomatic infections more like a 1:1 or 2:1 ratio.

So my advice is to ignore these sorts of estimates until people start doing widespread, random surveillance or, even better, testing for antibodies.  And that's probably months away at best.

[burger]

One thing that would result in an earlier peak is social distancing measures. Another is if prevalence is much higher than we expect. Say instead of unmeasured cases being 10x, they are actually 20 or 30x of measured cases. This means its spreading faster than initial models predicted, and so peak will be sooner. Also total deaths lower.

I suspect both of these are true to some extent.

Perhaps, although there's no universe where the prevalence rates are approaching where more have been exposed/infected than have not. Indeed, the best modeling I've seen done recently suggests the highest rates of infection are in Italy (est. of 9.8%) and Spain (15%). Even the worst (best?) case scenario estimates for prevalence in Italy are ~1/4 of the population infected. That is a long way off from herd immunity formation:

[tweet]https://twitter.com/joshmich/status/1244645729664106497?s=20[/tweet]

These Imperial College models are full of shit.  They can only get those giant numbers of infected people (the %s are small, but the numbers imply millions infected in each country) if they assume a giant number of asymptomatic or very mild infections--like 10+ asymptomatics for every symptomatic.  Data from places with heavy testing, like the Diamond Princess, suggest a much lower rate of asymptomatic infections more like a 1:1 or 2:1 ratio.

So my advice is to ignore these sorts of estimates until people start doing widespread, random surveillance or, even better, testing for antibodies.  And that's probably months away at best.