FIG. 1.

Summary “box-and-whiskers” plots based on the median, quartile, and extreme antibody values for the prevaccination sera from Icelandic teenagers evaluated for functionality (IRPA [a], SBA [b], OPA [c]) and quantity of meningococcal specific antibodies ([d to f]). On basis of the convergence or discrepancy of the IRPA and SBA data with the 44/76-SL (B:15:P1.7,16) strain, sera were divided into four different categories: category I, IRPA-positive, SBA-positive sera; category II, IRPA-negative, SBA-positive sera; category III, IRPA-positive, SBA-negative sera; and category IV, IRPA-negative, SBA-negative sera. The designated cutoff value (PI = 10) for IRPA is indicated by the horizontal dotted line.