On Monday, St. Louis County Executive Dr. Sam Page held a press conference to announce the results of COVID-19 tests taken in the county to measure active and past infections. From mid-August through mid-October, county residents were tested for active COVID-19 infections via nasal swab or past infections via antibody tests. The survey was commissioned by the County Department of Public Health and carried out by the Institute of Public Health at Washington University in St. Louis.
The results suggest that at least one out of every 100 adults in the county—about 9,500 people—had an active COVID-19 infection at some point during the testing period. Five out of every 100 people—about 39,000 residents—had COVID-19 antibodies, meaning they had contracted the disease earlier.
While those numbers, the first representative assessment of the burden of disease, may sound high, they actually raise concerns for researchers and public health officials. Antibodies likely confer immunity, and if only 5 percent of county residents are immune, that leaves a large portion of the population susceptible to the virus, especially with cases on the rise.
“With so many people actively infected with COVID-19 earlier this fall—and contagious—we’re already seeing that the illness can spread quickly to even larger portions of the population,” said Dr. Elvin Geng, a professor in the Division of Infectious Diseases at Washington University School of Medicine, in a statement. “The relatively small proportion of the population that had evidence of previous infection via antibody testing means that the size of the current surge we are experiencing in the region could be quite dramatic."
You can watch the full press conference below: