Efficacy of marker vaccine candidate CP7_E2alf in piglets with maternally derived C-strain antibodies

► The CP7_E2alf chimeric vaccine protects piglet against CSFV challenge. ► Maternal immunity from C-strain vaccinated sows can be overcome when vaccinating piglets at 5 weeks. ► Piglets with maternal immunity are partly protected when infected at 7 weeks of age. ► Using the CP7_E2alf to vaccinate 5-week-old piglets will result in a very reduced number of susceptible piglet.