We don't know what's behind the COVID-19 racial disparity. And that's a problem.

If you are in Belgium and have COVID-19, your odds are not good: About one in six Belgians who have contracted the disease have died. If you are in Rwanda, a former Belgian colony with a per capita GDP about 1/60th of Belgium’s, your odds are superb. Rwanda has reported 339 cases, and none has even required admission to an ICU. Rwandans are younger than Belgians, but zero is a very small number.

In Switzerland, a country with excellent universal health care, a French-speaking Swiss with COVID-19 is 1.6 times more likely to die than a German-speaking Swiss. An Italian-speaking Swiss is 2.4 times more likely to die than a German speaker. The magnitude of these disparities is comparable to the magnitude of the disparities among white, Latino, and black people in the United States—even though there is no modern history of enslavement and genocide of Switzerland’s Italian-speaking population. (Ticino, the center of Italian-speaking Switzerland, ranks seventh out of 26 cantons in per capita GDP.) You might be tempted to attribute the disparity to the Italian speakers’ connections with the death zone of northern Italy. That could account for the difference in the incidence of the disease—but why the difference in the likelihood that you’ll die, if you already have it?

Smaller puzzles abound. Why did the area around Milan get hit harder than almost anywhere on Earth, while Rome was spared? Why has Tokyo—which is densely populated, filled with old people, reliant on packed subways, and never fully shut down—not been crushed by the disease?