A preprint from some non-medical scientists at Berkeley:
Total COVID-19 Mortality in Italy: Excess Mortality and Age Dependence through Time-Series Analysis
Chirag Modi, Vanessa Bohm, Simone Ferraro, George Stein, and Uros Seljak
We perform a counterfactual time series analysis using two different Data Science methods applied to 2020 mortality data reported from towns in Italy, with data from the previous five years as control. We find an excess mortality that is correlated in time with the COVID-19 reported death rate time series. Our analysis shows good agreement with reported COVID-19 mortality for age<70 years, but an excess in total mortality increasing with age above 70 years, suggesting there is a large population of predominantly old people missing from the official fatality statistics. We estimate that the number of COVID-19 deaths in Italy is 52,000 ± 2000 as of April 18 2020, more than a factor of 2 higher than the official number. The Population Fatality Rate (PFR) has reached 0.22% in the most affected region of Lombardia and 0.57% in the most affected province of Bergamo, which constitutes a lower bound to the Infection Fatality Rate (IFR).
Let’s review our acronyms: Case Fatality Rate (CFR) is what percentage of officially counted diagnosed cases (which are less than all infections) die.
Infection Fatality Rate (IFR) is what percentage of all infections, diagnosed or not, die.
The Population Fatality Rate (PFR) is what percentage of all people, infected or not, die.
Of course, counting fatalities is not simple either. There are typically official counts of people who died in hospitals who were counted as being infected by the new virus. (That of course leads to arguments about dying from the virus versus dying with the virus.)
But, typically, there are many deaths outside hospitals, which often have gone uncounted initially.
In many places in northern Italy, excess deaths in 2020 versus the average for that time period in previous years was much higher than official CV deaths.
But that doesn’t mean they necessarily died directly of CV, whether from or with CV. They might have never been infected and died of something else altogether because either medical care was stressed or because they feared putting themselves in the hands of the medical care system during a period of rapid transmission of the new disease in medical settings.
We estimate PFR as a function of age, finding a steep age dependence: in Lombardia (Bergamo province) 0.6% (1.7%) of the total population in age group 70-79 died, 1.6% (4.6%) in age group 80-89, and 3.41% (10.2%) in the age group above 90.
So the good news about the bad news about all the uncounted deaths in Bergamo province was that they appear to have been concentrated among the quite old, even more so than the official counted deaths.
We combine this with the Test Positivity Rate to estimate the lower bound of 0.84% on the IFR for Lombardia.
We observe IFR to trace the Yearly Mortality Rate (YMR) above 60 years, which can be used to estimate the IFR for other regions in the world. We predict an IFR lower bound of 0.5% for NYC and 26% of total COVID-19 mortality arising from the population below 65 years, in agreement with the existing data and several times higher than Lombardia. Combining PFR with the Princess Diamond cruise ship IFR for ages above 70 we estimate the infection rates (IR) of regions in Italy, which peak in Lombardia at 23% (12%-41%, 95% c.l.), and for provinces in Bergamo at 67% (33%- 100%, 95% c.l.). This suggests that Bergamo may have reached herd immunity, and that the number of infected people greatly exceeds the number of positive tests, by a factor of 35 in Lombardia.
So, who knows about this methodology that these physicists and data scientists used? But these numbers don’t sound too implausible.
Here’s one thing I wanted to mention. I’ve read a lot of speculation about, “Well, of course old Italians are dying like flies. Everybody knows Italians are lazy, fat from eating all that pasta, and the industrial cities like Turin have terrible air pollution. (In contrast, I am, physically and morally, in perfect shape, so because, unlike Italians, I deserve to live forever, I can never die.)”
But … the more I read about the hardest-hit places in Italy, the more they sound like paradises for outdoorsmen.
For example, here’s a picture of the Upper Town of the city of Bergamo with the 10,000 foot tall Bergamasque Alps in the background.
Bergamo is so hilly that a 52 degree funicular was installed in 1887 to connect the Lower City to the Upper City.
Perhaps the hardest hit of all small cities was Nembro northeast of Bergamo, with an unofficial death toll over 1%.
Okay, so … perhaps instead the reason the death rate in Bergamo Province was so much higher among the old than among the young was not because the old were so unhealthy, but because the young are so healthy relative to, say, average Americans?
The good news is that doctors are learning far more about this novel disease every week, so they ought to be able to bring the Infection Fatality Rate down over time.