On May 25th the CDC released its most recent report on COVID-19. There is a lot of useful information in the report, but there are a couple of things I would like to spotlight.
The first key statistic is that their best guess estimate for the mortality rate of symptomatic cases is 0.4%. They also estimate an asymptomatic rate of 35%. Using that rate, it would bring the infection mortality rate of COVID to 0.26%.
Here is a quick chart comparing the CDC’s current best guess infection mortality rate of COVID to some bad years of the flu. The worst year recently was in 2018 which had an infection mortality rate of 0.13%
The question becomes if future estimates will go higher or lower. There is little doubt in my mind that it will continue to go lower because they are projecting a 35% asymptomatic rate, which is almost certainly low. This CDC report was based upon information through the end of April.
On May 5th, the CMMID Repository (Centre for Mathematical Modeling of Infectious Diseases) released a study reviewing the data from the Diamond Princess Cruise Ship. Their math indicated that the asymptomatic rate on that cruise ship was 74%, and this is in a population that averaged just under 60 years of age. At this point, we all know that COVID’s virulence decreases with age, so the overall rate of asymptomatic infections could be even higher than the 74% the CMMID is indicating.
Based on recent antibody studies, the rate may be as high as 90%, but that is not as solid as the math from the CMMID. Let’s just propose that the rate of asymptomatic cases is 75%. That would bring the infection mortality rate set by the CDC down to 0.1%.
In case you are not familiar with that number, it is generally associated with an “average” year of the flu. This means that the infection mortality rate of COVID is likely to be akin to the average year of the flu.
However, the problem with COVID is that it is highly contagious. This increases the chances of any one person becoming infected making it dangerous to us as a whole, even if it is not more severe individually. The good news is that it was a novel coronavirus and no longer is. COVID will never again be as dangerous as it was because it will never be new again.
And once we have a vaccine for the most vulnerable, it will be even less deadly. There is hope folks, the sky is not falling, and we are not entering a new normal.