Nicely conducted serological survey in Santa Clara as of April 4 finds COVID-19 prevalence of 2.81% (95%CI 2.24-3.37%). Prevalence estimates range from 48-81,000 people infected by early April, 50-85-fold more than the number of confirmed cases. https://t.co/MdWjudIW2I

— Nicholas A. Christakis (@NAChristakis) April 17, 2020