[timr]

"No regular influenza could do that."

Sure it could. The whole point of the IFR calculation is that it gives you an average perspective on how fatal a disease is, relative to other diseases. It's not an absolute maximum fatality rate, for every circumstance.

Put a strain of "normal" flu in a vulnerable population with no pre-existing immunity, and it would do a lot of damage. But if you don't count all the other people who had it without symptoms, then you get a misleading picture.

Also, of course, you have to realize that the population of "Lombardy" (~10M) is a bit larger than the population of New York City (~8M), where we see 100-300 deaths per day as a baseline mortality rate:

https://www.baruch.cuny.edu/nycdata/population-geography/pop...

[bonzini]

450 deaths a day was not the total, those were only those from confirmed COVID patients. Excess mortality was more like 650.

[timr]

Citation required (I've looked, and all I can find are annual mortality rates per capita, which are higher, certainly, but not double the rate for a year). Even if you're right, a doubling of baseline mortality per day is certainly something plausible for influenza in specific scenarios.

Italy as a whole is now seeing new cases per day roughly twice that observed in the spring, and yet deaths are up a tiny fraction of what you would expect from the Lombardy example. So it's not clear that Lombardy represents a typical outcome, even for Italy:

http://opendatadpc.maps.arcgis.com/apps/opsdashboard/index.h...

Point being, again, it's difficult to draw conclusions from data points that are on the extremes of the distribution. The IFR is a measurement of average behavior.

[bonzini]

Source: https://www.corriere.it/dataroom-milena-gabanelli/covid-risc... (in Italian). 45000 excess people are estimated to have died in about 60 days, for an average of 750 per day so I was even remembering fewer than the actual value.

Testing was awful in the spring, serological surveys were made in June and estimated that only 15% roughly of the cases were caught and other surveys estimated even lower percentages (as low as 6%). The territorial distribution is also much more even this time, so it is easier to cope for the healthcare system.

My point is that any a priori estimate of the IFR falls apart if the healthcare system fails and the purpose of lockdown is to avoid that. You don't lock down because it's the only way to keep the IFR down; you lock down when you realize that tracing is failing to capture and/or isolate many cases, and therefore lockdown is the only remaining way to keep the IFR down.

[timr]

OK, first, I need to say this: that news article has a number of false claims. Most notably, it claims that the fatality rate (# deceased / # infected) is 1-3%. Regardless of your opinions on the paper being discussed here, no credible source believes that the IFR for this virus is over 1%. That information is simply wrong.

That said, the claim for 45,000 excess deaths in March and April appears to come from this:

https://www.thelancet.com/journals/lancet/article/PIIS0140-6...

With this table having the details:

https://www.thelancet.com/cms/10.1016/S0140-6736(20)31865-1/...

The 45,000 number in that table is for all of Italy, whereas Lombardy specifically had excess mortality of 25,212 in March and April, with another ~700 in May. So that's 420 excess deaths a day in March/April, over a baseline of 275 (16,480 deaths in Lombardy, on average, for March and April of 2015-2019). This is nowhere near the 650 excess deaths per day you claimed in the GGP comment, but is a factor of about 2.5x over baseline.

For whatever it's worth, here's a paper that makes a claim of a much lower excess mortality figure of 5740 for Bergamo, and 3703 in Lombardy in the first four months of 2020, using better-controlled models for mortality in the regions:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7520169/

I think it's somewhat pointless to debate the exact number of people dying every day, because we'll never know, and in any case, the virus was clearly quite deadly in that place at that time. However, both of these sources note that excess mortality spiked in March and April, and by May, had returned to below normal levels. So whatever happened in Lombardy, it was a statistical anomaly, and we should be careful extrapolating from it.

Did the virus cause significant excess mortality in Lombardy in March and April? Yes. Could the flu cause similar levels of excess mortality in a naive population? It can, and it has. The 1958 pandemic killed about 116,000 people in the US, which is well above the 12,000-60,000 people we see per year in modern times, and worse on a population-adjusted basis:

https://www.cdc.gov/flu/pandemic-resources/1957-1958-pandemi...

https://en.wikipedia.org/wiki/United_States_influenza_statis...

People like to make comparisons to the 1918 pandemic, but if anything, Covid-19 appears to be on par with the 1958 pandemic in terms of overall severity.