Fig. 3.

A) Serum samples collected with PCR-confirmed diagnosis of seasonal respiratory viruses (Coronavirus OC43, blue; Coronavirus HKU-1, green; Coronavirus NL-63, pink; influenza A, orange, influenza B, red; parainfluenza, purple; rhinovirus, teal; respiratory syncycial virus, yellow; and adenovirus, black were run on the LFA as described in Methods. A positive control serum from a convalescent COVID-19 patient is shown on the far right of the bar graph in white. B) Serum samples collected pre-December 2019. Cutoff value of 263,000 density units was calculated based on receiver operating characteristic curves (see Fig. 6).