In this open-label Phase 3b, single arm trial, persistence of antibodies and long term safety in up to 375 participants rolled over from trial VLA1553-301 (NCT number: NCT04546724)
These participants will have annual follow-up visits at Months 12, 24, 36, 48, 60, 72, 84, 96, 108 and 120 after immunization. The primary objective of this trial will be to evaluate persistence of antibodies annually from 1 to 10 years after the single immunization with VLA1553. The secondary objective is to evaluate long-term safety 6 months to 2 years after the single immunization with VLA1553.
