Fig. 2

Transition of five HI titre pairs that exhibited a four-fold rise or greater in antibody titres against sH3N2 and pH1N1. The colour legend indicates the study rounds from which the sera pair was drawn. The start of each arrow represents titre values of the samples taken from the former study round and the end of the arrow represents that of the samples from the latter round. Titre values against pH1N1 is on x-axis and that against sH3N2 is on the y-axis. A small amount of noise was added to distinguish lines that start or end at the same coordinate