NUMBERS

March 26, 2020, Thursday

The headlines are alarming when they report that Covid-10 deaths in the U.S. are about  to overtake the number of those in Italy. But 82,000 cases in Italy with a population of about 61 million, and 82,000 cases in the U.S. with a population of 330 million are two different stories. What we usually see are only raw numbers and they have not been presented in any context.

The easiest and most obvious way to make a sensible comparison of the numbers is to relate them to the population of the area being reported: the per capita number or the percentage of people affected. Population figures are easy to obtain, but few journalists seem to be using them.

We're not even sure how accurate the raw numbers are;  let's assume they're roughly correct. But we often don't know what they're counting. Are the numbers of Covid-19 cases only those that have been confirmed? Some news outlets are beginning to use the term "known cases".  Several different kinds of tests are being used in California. Counties are requesting that all labs that process tests --- public heath, commercial, research, and hospital testing facilities --- report their numbers, not only the positive results, but also the total number of people tested. In California, tens of thousands of tests have not yet been processed.

Then there are more nuanced factors like the numbers of people who are infected but do not have obvious symptoms and have not been tested. How long before symptoms arise are people infectious? How long is a person with a confirmed diagnosis infectious? What is the length of time it takes to recover? How many people have been tested compared to the number not tested? If a person tests negative one day, they could test positive the following day if the disease is just getting started.

I hope we get more realistic reports as time passes. In the mean time, stay home, practice strict social distancing, and wash your hands.