COVID-19: A Lesson in Numbers

Our World in Data reports that there have been 4831 COVID-19 tests performed per million people in South Korea. The number of COVID-19 cases in South Korea currently stands at 159 per million people. Assuming that there is ample testing in Korea, the rate of positive COVID-19 tests is around 3 percent. This infection rate looks very promising. There is another piece of data that is equally reliable and this is the case of the cruise ship Diamond Princess, where virtually everyone has been tested. 696 out of 3711 people aboard this ship tested positive for the virus. This means a little less than 20 percent got infected. This is probably the worst case scenario since a cruise ship is similar to a Petri dish. The current fatality rate from the novel coronavirus for South Korea stands at about 0.9 percent, while for the cruise ship, it is 1 percent.  Thus, we have a range of numbers, for infection rate, South Korea provides 3 percent, and the cruise ship gives the worst case scenario of 20 percent. From both cases, the fatality rate seems to be close to 1 percent. This fatality rate, however, is dependent on age. Most of the fatalities involve the elderly and individuals with underlying health conditions.

While looking at these numbers, I read an article this morning from CTech. It was an interview of Nobel laureate and Stanford biophysics professor Michael Levitt:

Above copied from CTech

The part of this interview that caught my attention is the following:

Quarantine makes a difference, according to Levitt, but there are other factors at work. “We know China was under almost complete quarantine, people only left home to do crucial shopping and avoided contact with others. In Wuhan, which had the highest number of infection cases in the Hubei province, everyone had a chance of getting infected, but only 3% caught it,” he explained. “Even on the Diamond Princess (the virus-stricken cruise ship), the infection rate did not top 20%.” Based on these statistics, Levitt said, he concluded that many people are just naturally immune to the virus.
The explosion of cases in Italy is worrying, Levitt said, but he estimates it is a result of a higher percentage of elderly people than in China, France, or Spain. “Furthermore, Italian culture is very warm, and Italians have a very rich social life. For these reasons, it is important to keep people apart and prevent sick people from coming into contact with healthy people.”

The percent infection is not a hundred percent. Still, three percent of 7 billion is indeed staggering, it is 210,000,000. It is difficult to highlight Levitt's message especially when all of us need to be committed to keeping social distance, but we must not lose sight of this fact.  Still, China, with its 1 billion population, at this time, has only 81,000 cases, which is 0.008 percent. There is no perfect measure out there that can curb the spread of COVID-19 except for staying at home when one is feeling any one of the following symptoms COVID-19 brings: fever, cough, and shortness of breath. This is what we all need to do to prevent us from reaching 210 million cases.