How to Know If You Can Trust That Headline-Grabbing COVID-19 Study

There has been a lot of talk lately about a few COVID-19 studies that use antibody testing to estimate the prevalence of infection across the population. In theory, antibody tests detect evidence that a person has already had and recovered from COVID-19, which, given the lack of available testing while people are still experiencing symptoms (or may be experiencing only mild symptoms, if they aren’t completely asymptomatic), can be a useful tool for estimating the full scope of the pandemic.

In particular, a study of prevalence rates in Santa Clara...