As coronavirus disease 2019 (COVID-19) raged around the globe in late March, hundreds of San Miguel County, Colorado, residents turned out for a blood test. Standing 6 feet apart outside a Telluride school gym, they waited for the blood draw that would tell them whether they had mounted an immune response to the disease-causing virus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)—a sign that they’d been infected.
In the first such community-wide campaign in the US, the San Miguel County Department of Health offered the voluntary screening to most of the area’s 8000 residents over 2 weeks. Just 8 of the 986 individuals tested on March 26 and 27 were positive for SARS-CoV-2 antibodies. Another 23 were borderline, suggesting that they’d recently been exposed to the virus and were just starting to make antibodies against it. But those were early days. The screenings, paid for by test manufacturer United Biomedical Inc and the county, eventually would be repeated to see how much things had changed.