Randomized, observer-blinded, multicenter, dose-escalation Phase 1 clinical study investigating three dose levels of VLA1553 after a single immunization.

120 study participants will be enrolled into the study to receive three different doses (30 subjects in the low and medium and 60 subjects in the high dose group). Vaccination will be given intramuscularly on Day 0. As safety precaution, the study will begin with enrolment of 20 sentinel subjects in an open-label fashion. Thereafter, subjects will be enrolled in a blinded, randomized manner in the three study arms.

A re-vaccination will be given at Month 6 or Month 12 to confirm that a single vaccination will be sufficient to induce high titer neutralizing antibodies and protect subjects from CHIKV viremia.

Study participants will be followed up until 13 months after initial vaccination.

Results

On August 29, 2019: Phase 1 unblinded results up to month 7 showed excellent immunogenicity and safety profile confirming Valneva's unique, single-shot vaccine candidate. These results strongly support further development acceleration. On June 1, 2020, The Lancet published a summary of this phase 1 study.