FIG 2.

Vaccination and prior infection prevent leukocytosis. Unvaccinated animals (n = 4), DTaP-vaccinated animals (n = 3), convalescent animals (n = 3), and animals vaccinated with DTwP (Triple Antigen, DT-COQ, or Quinvaxem; n = 2 per group) were directly challenged with B. pertussis (n = 2 to 4 per group). The mean circulating white blood cell counts before and after challenge are shown for each group of animals. *, P < 0.05 versus preinfection from the same group. For each group, the mean count is presented at every time point with error bars representing the SE.