Implied COVID spread in Bergamo (Italy)

Post #784

In this prior post, the uncanny excess death found in Bergamo province in Italy was documented. But in an earlier post, the upper bound infection fatality rate of wild-type COVID was found to be 0.196%. Applying that IFR to the weekly excess deaths in Bergamo up to the week beginning 6 May 2020 reveals astonishing COVID spread:

If COVID infections were thought to explain 100% of the excess deaths, then 100% of the people of Bergamo would have had COVID by the week beginning 11 Mar 2020. Before the week beginning 25 Mar 2020, everyone in Bergamo would have gotten COVID a second time. By April Fool’s Day, the average person had it 2.5 times.

The highest spread ever expected from disease is approximately 90%, with 10% of a given population innately immune. Even relaxing assumptions — e.g., doubling the upper bound IFR to 0.392% so as to account for a high age distribution — does not make the numbers conducive to a realistic epidemiology of contagious disease:

Even at double the upper bound infection fatality rate, you cannot explain the excess deaths in Bergamo by postulating that it was due to the spread of a viral disease. Before the week beginning 25 Mar 2020, over 100% of residents would have already had to have been infected.

A complement to this post, focusing on New York City instead, is found here.