Fig. 1.

Agreement between dried blood spot (DBS) and reference serum at 7 days post-collection A. Agreement between qualitative results, where each OD ratio was categorized as being IgG negative, IgG positive or equivocal based on the manufacturer's test cutoff values. Only the first DBS spot analyzed 7 days post-collection is presented, and the agreement is summarized using Cohen's κ. B. Association between quantitative results, showing the Pearson correlation between DBS and reference serum OD ratio for the first DBS spot analyzed 7 days post-collection. C. Differences between DBS and reference serum OD ratios versus the average ratios using all spots per study participant 7 days post-collection. PA = phlebotomist acquired sample; Self = self-stick acquired sample.