Is there any light at the end of this dark tunnel that is not the headlight of an oncoming train?
There are some glimmers of hope in the data from China and South Korea where they seemed to have successfully “controlled” their COVID-19 infection. This does not mean that they have no new cases and certainly does not mean that they have no more deaths. It just means that they have flattened the curve, and reduced the number of active cases in their country. The number of net new infections — i.e., the number of confirmed cases minus the number of resolved cases (deaths plus cures) — is an important statistic to track (shown in the last column in the table below).
The number of net new infections is an important statistic to track because it tells us whether the situation is likely to get out of control. If this number is increasing every day the country might run out of hospital beds and doctors and lose their ability to treat every patient well. If this number plateaus or decreases it means that enough patients leave the system to allow new patients to be handled properly. For China, this statistic turned negative on Feb 18 when the number of newly recovered and dead exceeded the number of newly infected. This occurred 26 days after they locked down Wuhan and Hubei Province. For South Korea, they flattened the curve on Mar 11th, roughly a month after their infections started to accelerate in mid-February. For some countries like Singapore, Taiwan, and Hong Kong they seemed to have been able to control their infections for periods of time. However, as COVID-19 has spread globally, these countries have experienced periods of re-infection from international travelers.
The other important “good news” is that the basic underlying mortality for COVID-19 is closer to 1% rather than the WHO estimate of 3.4%. The table below summarizes the data for China, South Korea, and Singapore and gives their infection rate per million citizens, the total infections experienced to date, the total death count, and the mortality rate estimated three different ways: using contemporaneous data, using time-lagged data, and using resolved case data. The coincident mortality rate is the easiest to calculate for all countries and merely takes the total death count and divide it by the cumulative number of confirmed cases. For a rapidly spreading infection, this estimate is always too low but for a mature outbreak, this estimate is more correct. This lagged5 mortality rate is calculated as the death count divided by the average case count 3–7 days prior. In general, it takes about that amount of time for a confirmed diagnosis to result in death. For outbreaks that are near the end, we can just look at the final death count and divide it by the total cases resolved. For China, all three estimates are very close to 4.0% with the resolved case estimate falling slowly toward 4% as more patients finally get released from the hospitals. This rate for China is high due to the disastrous situation in Wuhan where the health care system was overwhelmed. The mortality rate in the rest of China is closer to the base mortality rate of 1% experienced by other countries whose health systems were able to keep up with the infection spread. You can see in South Korea the mortality rate estimate has held steady near 1% for weeks. They also have one of the best health systems in the world in terms of hospital beds per capita –1.2%. Singapore has had no deaths for about 2 months and even after reporting their first two deaths yesterday they still show a reasonable low mortality rate, albeit with large statistical errors.
In our opinion, the prescription for success in the COVID-19 fight — measured in terms of limiting the total number of death per million citizens — is:
- Test, track, and treat every possible case immediately — US
- Enforce strict travel restrictions and social distancing rules immediately
- Endure one month of hardship until the curve turns — Italy
- Endure another month of more bad news regarding high infections and deaths — South Korea
- Be sure to vigorously attack re-infections — China, Singapore, Taiwan, HK
- Light at the end of the tunnel with just 1% of those infected dying over the next 2 months — better than the millions currently projected for the US with little action.