This is a prospective, randomized, double-blinded, multicenter Phase 3 clinical study investigating three Lots of VLA1553.

Overall, approximately 402 healthy subjects aged 18 to 45 years will be enrolled into the study, approximately 134 subjects per VLA1553 Lot.

Subjects will be block-randomized in a 1:1:1 ratio into the three study arms to receive one of three Lots of VLA1553 as a single i.m. vaccination.

The primary objective is to demonstrate Lot-to-Lot manufacturing consistency of VLA1553 28 days following vaccination.