Effect of intraperitoneal vaccination on survival of fish infected with a lethal dose of Piscirickettsia salmonis. Fish subjected to vaccination and challenged by intraperitoneal inoculation against P. salmonis. Survival was monitored on a daily basis. Kaplan–Meier and subsequent survival curves comparison by Log-rank test. Asterisks show statistically significant differences between groups and denote: **** p ≤ 0.0001. Red light line shows 50% cumulative survival.