Survival of S. suis in blood drawn from vaccinated or placebo-treated piglets. Eleven days after booster immunization with a multicomponent vaccine or application of a placebo blood was drawn from 8-week-old piglets (n = 8 per group) and incubated with S. suis strains V3117/2 (cps14), 10 (cps2) and 16085/3b (cps9). Significant differences were not recorded between vaccinated and placebo-treated piglets in these bactericidal assays using the Mann–Whitney-U test. The survival factor represents the ratio of CFU at 120 min to CFU at timepoint zero. Bars and error bars represent mean values and standard deviations, respectively.