COVID-19 official counts can miss mild cases – here's how serosurveys that analyze blood for signs of past infection can help
- Written by Isobel Routledge, Postdoctoral Scholar in Medicine, University of California, San Francisco

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...