In this Phase 1 study, two target dose levels of VLA1601, a purified, inactivated, whole Zika virus (ZIKV) vaccine candidate adsorbed on aluminum hydroxide (alum) will be evaluated: 6 antigen units (AU) and 3 AU of inactivated ZIKV vaccine.

Each dose will be administered intramuscularly (i.m.) in the deltoid muscle on Days 0 and 28. In addition, an accelerated 2-dose vaccination schedule on Days 0 and 7 will be assessed for both doses.