COVID-19: Down the Rabbit Hole of Death Rate Calculations - Part 6

Note: Written June 26th

Using information from the Diamond Princes, I calculate an Infection Fatality Rate (IFR) of 5.6%. This assumes that the total number of infections can be obtained by knowing the number of confirmed cases and adding 17.9% more to cover the asymptomatic cases that were never tested because,,,well they never knew they were sick.

The issue with this IFR calculation is that it is based on what took place within a population with a median age over 60.

Need more better data!

The WorldoMeters calculates a mortality rate by looking at antibody testing performed in New York and the data out of New York they reported this.

Considering that a large number of cases are asymptomatic (or present with very mild symptoms) and that testing has not been performed on the entire population, only a fraction of the SARS-CoV-2 infected population is detected, confirmed through a laboratory test, and officially reported as a COVID-19 case. The number of actual cases is therefore estimated to be at several multiples above the number of reported cases. The number of deaths also tends to be underestimated, as some patients are not hospitalized and not tested.

Based on the "analyzed the data provided by New York City, the New York State antibody study, and the excess deaths analysis by the CDC. Combining these 3 sources together we can derive the most accurate estimate to date on the mortality rate for COVID-19, as well as the mortality rate by age group and underlying condition."

The survey developed a baseline infection rate by testing 15,103 people at grocery stores and community centers across the state over the preceding two weeks. 

What they found was:

• 12.3% of the population in the state had COVID-19 antibodies as of May 1, 2020.
• 19.9% of the population of New York City had COVID-19 antibodies.

Looking at New York City...:

With a population of 8,398,748 people in NYC, this percentage would indicate that 1,671,351 people had been infected with SARS-CoV-2 and had recovered as of May 1 in New York City. The number of confirmed cases reported as of May 1 by New York City was 166,883, more than 10 times less.

What this says to me is that if you were tested and found with antibodies you were past the active infection period and on May 1 you had ether recovered or died. I am going to calculate this a bit different than WorldoMeters because I am going to assume the deaths on May 1 happened 7 days prior. So I am going to look at the deaths reported in NYC on May 9. [I am using 7 days to account for the lag in reporting the deaths, so if we stop on May1 our deaths should - should - be accounted for in the May 9th report]

The IFR is therefore [total deaths] divided by [total recovered plus total deaths].This gives me the pool to pull from, what portion died and what portion survived.

If the New York serum data is correct, we have an IFR of 0.86 to 1.17%. What this could mean in terms of deaths of real people should we continue down the path of waiting for herd immunity as the stopping point looks like this:

If my calculations are correct, and y'all can check my math, if we rely on herd immunity - as some are recommending - we could see 1.97 to 2.68 million of our fellow Americans dead assuming 70% needed to reach herd immunity.

Maybe Boston presents a better estimate...

Down the rabbit hole to Boston we go!

Part 7