Why the silent spread of coronavirus might actually be a good sign

In China, the death rate has been reported as zero in children under 10 and very low, 0.2 percent, in healthy adults. Unfortunately, the rate is far higher, as high as 14.8 percent, in the sick and elderly (though as is always the case in outbreaks like this, it is hard to know how many of these older and often chronically ill hospitalized patients died with COVID-19, not of COVID-19). The reported overall death rate of 2 percent is essentially a weighted average of these numbers.

So what does the case of a young and otherwise healthy patient contracting the disease despite no obvious exposure to a contagious source patient imply? That there are likely many asymptomatic cases in our communities already. Asymptomatic transmission has already been reported in China. In the first reported case, the source patient transmitted the infection to others but never became sick herself.

If this turns out to be common, it’s a good thing. It implies that the case fatality rate—the number of deaths divided by the number of infections—of this novel coronavirus is likely to be far, far lower than the reported statistics.