COVID-19 may have hit Blaine County harder than previous testing numbers indicated, according to initial findings from an antibody study that was conducted throughout the county following a surge of cases in March and April.
The results estimate that 23 percent of the county’s adult population has an antibody to the coronavirus, meaning they were exposed, the City of Ketchum announced Tuesday afternoon.
The study aims to identify the prevalence of COVID-19 antibodies in symptomatic and asymptomatic individuals to determine how many asymptomatic cases there are in the community.
While the rate of COVID-19 infection in the county was significant, Ketchum bore the brunt of those infection rates. Antibody prevalence was highest in Ketchum at 35 percent, one of the highest rates per capita in the nation.
Of the more than 2,500 valley residents who completed the survey for possible participation in the study, tests were administered to 917 of those who were selected.
That percentage would translate to roughly 4,100 Blaine County adults exposed to the virus, eight times the amount of confirmed and probable cases reported by the South Central Public Health District. (Those numbers are based on a countywide population of roughly 23,000, according to the most recent census data, removing the 22 percent under the age of 18.)
“Our valley is certainly doing its part to help further the understanding of the coronavirus,” Ketchum Mayor Neil Bradshaw said in the city’s statement. “There is no doubt that COVID-19 hit us hard. Our recovery is testament to the health and safe practices of our community.”
The study was a collaboration between the Ketchum Fire Department, Blaine County Ambulance District, University of Washington, Albany College of Pharmacy and Health Sciences, and the Fred Hutchinson Cancer Research Center. The test they used in Blaine County has a specificity of 99.9 percent, according to the city, meaning only one in every one thousand would yield a false positive result.
While the antibodies may confer immunity, research is still underway to confirm that. Currently, most researchers estimate that 60 percent or more of the population might need immunity to reach a herd immunity threshold. Ketchum has not yet reached that milestone.