Figure 1From: Persistence of antibodies in laboratory staff immunized with quadrivalent meningococcal polysaccharide vaccineKinetics of serum bactericidal antibody titers against meningococci of serogroups A, C, W135, and Y. Obs: observed titers, D: mean decay, PI: 95% prediction interval, PT: protective threshold, 5Y%: cropped contour line representing percentile of prediction interval below protective threshold five years after vaccination.Back to article page