It’s an eye-catching statistic: 58% of the whole population and 75% of kids in the U.S. had been infected by the coronavirus by the end of February 2022. That’s a pretty big jump from the official case count that hovered around a quarter of Americans having been diagnosed with COVID-19. A report from the U.S. Centers for Disease Control and Prevention based these higher proportions on what’s called a serosurvey: a study that looks at people’s blood to see if they’ve had a particular illness.
Isobel Routledge is an infectious disease epidemiologist who uses serosurveys in her own research. Here she explains the science behind the approach and what a serosurvey can – and can’t – tell you.
