A Phase 1 interventional study of VLA1601 and CpG 1018® in Zika and Zika Virus Infection, sponsored by Valneva Austria GmbH. Completed at 4 sites in United States. Open to participants aged 18 Years to 49 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2026-03-09.
Sponsored by Valneva Austria GmbH · Phase 1, Interventional, and Prevention
This phase 1 clinical trial consists of an initial open-label sentinel run-in (n=25) and a randomized, double-blind, dose-finding (n=125) investigating three antigen dose levels (low, medium and high) of VLA1601 and bedside mixing of the low-dose formulation with one of the two additional adjuvants (CpG1018®, 3M-052-AF/AP 60-702). VLA1601 will be administered according to a two-dose regimen (i.e., on Day 1 and Day 29).
The primary objective of this trial is to assess the safety and tolerability of the vaccine candidate up to 7 days after each vaccination; and to assess the immune response induced by the vaccine candidate 28 days after the second vaccination. Additionally, safety and immune response of the vaccine candidate will be monitored throughout the trial.
VLA1601 is a second generation, highly purified, inactivated, whole ZIKV vaccine candidate (adsorbed on aluminum hydroxide) designed for active immunization for the prevention of disease caused by the flavivirus ZIKV.
This is a phase 1 trial, consisting of an initial open-label sentinel run-in (n=25) phase and a randomized, double-blind, dose-finding trial (n=125) in flavivirus naïve adults aged 18 to 49 years. In total approximately 150 participants will be vaccinated in this trial.
The trial will investigate three antigen dose levels (low, medium and high) of VLA1601. In addition, CpG 1018® or 3M-052-AF/AP 60-702 are investigated as add-on adjuvants in the low dose group (bedside mixing). Each dose is formulated with alum (aluminum hydroxide) adjuvant.
In each of the five treatment arms 30 participants (each with 5 sentinel/run-in and 25 randomized participants) will be vaccinated. Each participant will receive 2 vaccinations, one on Day 1 and one on Day 29, which will be administered intramuscularly (i.m.) in the deltoid muscle (non-dominant arm). The screening period can last up to 21 days.
The trial began with the vaccination of 25 sentinel participants (5 participants in each of the 5 treatment arms) in a sequential open-label, staggered dose-escalation manner.
Up to approximately 125 participants will be randomized 1:1:1:1:1, stratified by trial site to 5 treatment arms. The injection volume in each treatment arm will be 0.45 mL at each of the 2 vaccinations.
The primary objective of this trial is to assess the safety and tolerability of the vaccine candidate up to 7 days after each vaccination; and to assess the immune response induced by the vaccine candidate 28 days after the second vaccination.
Following a sponsor review of available safety and immunogenicity data up to 6 months after the second vaccination, all sentinels and randomized participants from most favorable treatment arm(s) will be selected for an on-site visit at Day 395 for long-term safety and immunogenicity assessment. All other treatment arms will be followed only by phone-call for the Day 395 assessment of long-term safety.
63 studies on the registry are indexed under Zika Virus Infection; 5 are open to participants now.
This study's enrollment of 150 is above the median of 85 across 34 interventional studies indexed under Zika Virus Infection.
Browse Zika Virus Infection studies →Valneva Austria GmbH is the lead sponsor of 44 studies on the registry; 2 are open to participants now.
Of its 7 completed or terminated interventional studies of FDA-regulated products, 4 (57%) have results posted.
Counted across the registry records on this site, refreshed daily.
Key Inclusion Criteria:
Key Exclusion Criteria:
Participant
Biological: VLA1601
Biological: VLA1601 · Biological: CpG 1018®
Biological: VLA1601 · Biological: 3M-052-AF
Biological: VLA1601
Biological: VLA1601
0.45mL (milliliter), Day 1 and 29
CpG 1018® will be investigated in combination with VLA1601 Low dose
3M-052-AF will be investigated in combination with VLA1601 Low dose
Solicited Adverse Events
frequency of solicited AEs (injection site and systemic reactions)
Time frame: 7 days after each vaccination
Solicited Adverse Events
severity of solicited AEs (injection site and systemic reactions)
Time frame: 7 days after each vaccination
Neutralizing antibodies against ZIKA virus (ZIKV)
Geometric mean titer (GMT) for neutralizing antibodies against (ZIKV) determined by virus neutralization assay
Time frame: Day 57
Solicited Adverse Events
frequency of solicited AEs (injection site and systemic reactions)
Time frame: 7 days after any vaccination
Solicited Adverse Events
severity of solicited AEs (injection site and systemic reactions)
Time frame: 7 days after any vaccination
Unsolicited AEs
frequency of unsolicited AEs
Time frame: Day 395
Unsolicited AEs
severity of unsolicited AEs
Time frame: Day 395
Vaccine-related unsolicited AEs
frequency of vaccine-related unsolicited AEs
Time frame: Day 395
Vaccine-related unsolicited AEs
severity of vaccine-related unsolicited AEs
Time frame: Day 395
Any AEs
severity of any AEs (including solicited and unsolicited AEs)
Time frame: Day 395
Any AEs
frequency of any AEs (including solicited and unsolicited AEs)
Time frame: Day 395
Any vaccine-related AEs
severity of any vaccine-related AEs (including solicited and unsolicited AEs)
Time frame: Day 395
Any Vaccine-related AEs
frequency of vaccine-related AEs (including solicited and unsolicited AEs)
Time frame: Day 395
Adverse Events of Special Interest (AESI)
severity of AESI
Time frame: Day 395
Adverse Events of Special Interest (AESI)
frequency of AESI
Time frame: Day 395
Vaccine-related Adverse Events of Special Interest (AESI)
frequency of vaccine-related AESI
Time frame: Day 395
Vaccine-related Adverse Events of Special Interest (AESI)
severity of vaccine-related AESI
Time frame: Day 395
Serious Adverse Events (SAE)
frequency of SAEs
Time frame: Day 395
Serious Adverse Events (SAE)
severity of SAEs
Time frame: Day 395
Vaccine-related Serious Adverse Events (SAE)
frequency of vaccine-related SAEs
Time frame: Day 395
Vaccine-related Serious Adverse Events (SAE)
severity of vaccine-related SAEs
Time frame: Day 395
ZIKV-specific neutralizing antibodies
Geometric Mean Titer (GMT) as determined by virus neutralization assay
Time frame: up to Day 395 (including Day 1, 15, 29, 43, 208)
Seroconversion rate (SCR)
Rate of participants with seroconversion (SCR defined as proportion of participants achieving a \>4-fold increase in neutralizing anti-ZIKV antibody titer from baseline) compared to baseline determined by virus neutralization assay
Time frame: up to Day 395 (including Day 1, 15, 29, 43, 57, 208)
Geometric Mean Fold Increase (GMFI)
Geometric Mean Fold Increase compared to baseline determined by virus neutralization assay
Time frame: up to Day 395 (including Day 1, 15, 29, 43, 57, 208)
Plan to share: Yes — After trial completion, Valneva may provide access to individual de-identified participant data and related trial documents (e.g. protocol, Statistical Analysis Plan (SAP), Clinical Trial Report (CTR)) upon request from qualified researchers, and subject to Valneva's review and approval.
No publications or documents are linked to this record.
This study is completed, as verified in Mar 2026. You cannot join it, but the record below documents what was studied.
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Valneva Austria GmbH