Estimated SARS-CoV-2 seroprevalence in the US as of September 2020

A CDC-led investigation estimated the share of people across the United States and Puerto Rico who had detectable coronavirus antibodies during July–September. Researchers examined nearly 178,000 residual clinical specimens provided by two private commercial laboratories for individuals of all ages. Over four distinct sampling periods during the 3-month study period, they discovered that seroprevalence differed significantly from jurisdiction to jurisdiction, from as low as 1% to as high as 23%. Even so, the investigators found that most people in the United States—fewer than 10% in 42 of 49 jurisdictions with adequate samples for estimation—showed signs indicating they had previously been infected with coronavirus. Seroprevalence varied not only by jurisdiction but also according to age, gender, and metropolitan/nonmetropolitan classification. According to the team behind the study, “biweekly nationwide testing of commercial clinical laboratory sera can play an important role in helping track the spread of [coronavirus] in the US.”