Fig 1. Pre-challenge reduces viral shedding in homologous challenge.

Patterns of CL shedding in pre-challenged and control groups for different age and time intervals at re-challenge. The panels show the variation in intensity of shedding (40 –mean Ct-values per group and standard error of the mean (SE), no data points indicate negative RRT-PCR, lines are drawn between days with consecutive positive results) for the different groups: initial pre-challenge and 5-, 11- or 15- week intervals between H3N8 homologous infections. Continuous lines and circles indicate the control groups and dashed lines with filled dots indicate the H3N8 pre-challenged groups. This indicates that pre-challenge induced protection and suppressed CL shedding.