by Will Schreiber

~2,412 people in the U.S. have SARS-CoV-2 (as of 3/5/2020)

South Korea is doing the best job testing for COVID-19.

They haven’t shut down internal migration like China (which leads to undiagnosed patients stuck inside apartments) and they’re offering exams in clinics and drivethroughs.

They’ve tested 140,000 people, resulting in 5,766 detected cases and 35 deaths. (So far.)

This implies a blended death rate of 0.607%.1

With 11 deaths and 154 reported cases, the U.S. has an implied death rate of 7.14%.


Either the virus has mutated, or we’re vastly under-reporting the number of cases in the U.S. Proof we’re under-testing, and thus under-reporting, is that the U.S. is an extreme outlier in tests coming out positive:


If COVID-19 has an actual death rate of 0.607%, and the U.S. has already recorded 11 deaths, then the U.S. should actually have around 1,812 active COVID-19 cases at the moment.

The average age of a population could affect the death rate, though. Countries with younger people could fare better than those with older people, like Italy.

42.3% of South Korea’s population is over the age of 60, compared to only 32.4% in the U.S.4

The death rate of patients 60 years old and older ranges from 3% on the young end to 20% on the oldest end, compared to only ~0.3% for everybody under the age of 60.

Based on stats I’ve seen in China,5 patients older than 60 are responsible for 81.0% of deaths. Thus, the proportion of the population that’s above-60 accounts for ~81% of the death rate potential.

If there are relatively 30.5% more people aged 60+ in South Korea as compared to the United States, then we should expect the death rate in the United States to be (1-0.81*0.305)*0.00607 = 0.457%.

And if the death rate in the U.S. is really 0.456%, then the number of implied cases (based on 11 deaths) is 2,412.

  1. Note, this number is likely low because there are still active cases in critical condition that will likely eventually add to the death toll. But it’s an optimistic and fairly realistic number to use.

  2. US Case Fatality Rate from #covid19 very lofty vs other DM countries

    At 7% vs the 1% average of other countries, the CFR suggests the number of cases could be massively understated

    Confirmed cases may soar as wide-spread testing starts

    H/T @darky999

    — Martin Enlund 🦆🚁 (@enlundm) March 5, 2020

  3. Few tests - Few infected. More tests to come: On March. 2, Dr. Stephen Hahn, FDA Commissioner, announced that the US will have, by the end of the week, the ability to perform 1 million tests.

    — Christian Börjesson (@cborjesson) March 5, 2020

  4. The median age in South Korea is 52.5yo vs. 44.3yo in the U.S.