Trial Outcomes & Findings for Antibody Persistence And Long Term Safety Of A Chikungunya Virus Vaccine (VLA1553) (NCT NCT04838444)
NCT ID: NCT04838444
Last Updated: 2026-07-09
Results Overview
Data for Visit 1 - Day 1 are collected from Trial VLA1553-301
Recruitment status
ACTIVE_NOT_RECRUITING
Study phase
PHASE3
Target enrollment
363 participants
Primary outcome timeframe
Year 2
Results posted on
2026-07-09
Participant Flow
Participant milestones
| Measure |
VLA1553
Participants previously vaccinated with VLA1553 in trial VLA1553-301 will be followed up for safety and immunogenicity.
|
|---|---|
|
Overall Study
STARTED
|
363
|
|
Overall Study
COMPLETED
|
317
|
|
Overall Study
NOT COMPLETED
|
46
|
Reasons for withdrawal
Withdrawal data not reported
Baseline Characteristics
Antibody Persistence And Long Term Safety Of A Chikungunya Virus Vaccine (VLA1553)
Baseline characteristics by cohort
| Measure |
VLA1553: 18 - 64 Years
n=310 Participants
Participant aged between 18 - 64 Years
|
VLA1553: >=65 Years
n=53 Participants
Participants aged \>=65 Years
|
Total
n=363 Participants
Total of all reporting groups
|
|---|---|---|---|
|
Age, Customized
|
44.1 years
STANDARD_DEVIATION 12.02 • n=20 Participants
|
68.7 years
STANDARD_DEVIATION 3.37 • n=20 Participants
|
47.7 years
STANDARD_DEVIATION 14.15 • n=40 Participants
|
|
Sex: Female, Male
Female
|
177 Participants
n=20 Participants
|
30 Participants
n=20 Participants
|
207 Participants
n=40 Participants
|
|
Sex: Female, Male
Male
|
133 Participants
n=20 Participants
|
23 Participants
n=20 Participants
|
156 Participants
n=40 Participants
|
|
Ethnicity (NIH/OMB)
Hispanic or Latino
|
40 Participants
n=20 Participants
|
3 Participants
n=20 Participants
|
43 Participants
n=40 Participants
|
|
Ethnicity (NIH/OMB)
Not Hispanic or Latino
|
265 Participants
n=20 Participants
|
49 Participants
n=20 Participants
|
314 Participants
n=40 Participants
|
|
Ethnicity (NIH/OMB)
Unknown or Not Reported
|
5 Participants
n=20 Participants
|
1 Participants
n=20 Participants
|
6 Participants
n=40 Participants
|
|
Race/Ethnicity, Customized
American Indian or Alaska Native
|
2 Participants
n=20 Participants
|
0 Participants
n=20 Participants
|
2 Participants
n=40 Participants
|
|
Race/Ethnicity, Customized
Asian
|
6 Participants
n=20 Participants
|
0 Participants
n=20 Participants
|
6 Participants
n=40 Participants
|
|
Race/Ethnicity, Customized
Native Hawaiian or Other Pacific Islander
|
2 Participants
n=20 Participants
|
1 Participants
n=20 Participants
|
3 Participants
n=40 Participants
|
|
Race/Ethnicity, Customized
Black or African American
|
44 Participants
n=20 Participants
|
8 Participants
n=20 Participants
|
52 Participants
n=40 Participants
|
|
Race/Ethnicity, Customized
White
|
237 Participants
n=20 Participants
|
43 Participants
n=20 Participants
|
280 Participants
n=40 Participants
|
|
Race/Ethnicity, Customized
Other
|
19 Participants
n=20 Participants
|
1 Participants
n=20 Participants
|
20 Participants
n=40 Participants
|
PRIMARY outcome
Timeframe: Year 2Population: The Per Protocol Population (PPP) is a subset of the WSP and contains * All participants who were CHIKV-seronegative at baseline (defined as μPRNT50 titer ≤40). * Have at least one or more evaluable post-baseline titer measurements at either Day 29, Day 85 or Day 180 (within SAP visit windows for trial VLA1553-301). * In addition, the participants must have no major PDs at the start of VLA1553-303 trial being analyzed that could impact immune response.
Data for Visit 1 - Day 1 are collected from Trial VLA1553-301
Outcome measures
| Measure |
VLA1553: 18 - 64 Years
n=290 Participants
Participant aged between 18 - 64 Years
|
VLA1553: >=65 Years
n=49 Participants
Participants aged \>=65 Years
|
|---|---|---|
|
Proportion of Participants With Seroresponse Levels Post-vaccination. (Defined as µPRNT50 ≥150)
Visit 1 - Day 1
|
0 percentage of participants with SRR
Interval 0.0 to 0.0
|
0 percentage of participants with SRR
Interval 0.0 to 0.0
|
|
Proportion of Participants With Seroresponse Levels Post-vaccination. (Defined as µPRNT50 ≥150)
Visit 1 - Year 1
|
99.4 percentage of participants with SRR
Interval 96.5 to 100.0
|
100 percentage of participants with SRR
Interval 87.2 to 100.0
|
|
Proportion of Participants With Seroresponse Levels Post-vaccination. (Defined as µPRNT50 ≥150)
Visit 2 - Year 2
|
97 percentage of participants with SRR
Interval 93.9 to 98.8
|
97.6 percentage of participants with SRR
Interval 87.4 to 99.9
|
SECONDARY outcome
Timeframe: until Year 2Outcome measures
Outcome data not reported
SECONDARY outcome
Timeframe: until Year 2Outcome measures
Outcome data not reported
SECONDARY outcome
Timeframe: until Year 10Outcome measures
Outcome data not reported
SECONDARY outcome
Timeframe: until Year 10Outcome measures
Outcome data not reported
SECONDARY outcome
Timeframe: until Year 10Outcome measures
Outcome data not reported
SECONDARY outcome
Timeframe: until Year 10Outcome measures
Outcome data not reported
Adverse Events
VLA1553: 18 - 64 Years
Serious events: 6 serious events
Other events: 0 other events
Deaths: 1 deaths
VLA1553: >=65 Years
Serious events: 2 serious events
Other events: 0 other events
Deaths: 0 deaths
Serious adverse events
| Measure |
VLA1553: 18 - 64 Years
n=310 participants at risk
Participant aged between 18 - 64 Years
|
VLA1553: >=65 Years
n=53 participants at risk
Participants aged \>=65 Years
|
|---|---|---|
|
Injury, poisoning and procedural complications
Gun shot wound
|
0.32%
1/310 • Number of events 1 • Long-term safety (i.e. Serious Adverse Events [SAEs]) was collected 6 months to 2 years after the single immunization with VLA1553.
Only new information on ongoing SAEs from the precursor trial VLA1553-301 and new SAEs since the end of the VLA1553-301 trial had to be captured. AEs which did not fulfil the criteria for an SAE did not have to be captured.
|
0.00%
0/53 • Long-term safety (i.e. Serious Adverse Events [SAEs]) was collected 6 months to 2 years after the single immunization with VLA1553.
Only new information on ongoing SAEs from the precursor trial VLA1553-301 and new SAEs since the end of the VLA1553-301 trial had to be captured. AEs which did not fulfil the criteria for an SAE did not have to be captured.
|
|
Injury, poisoning and procedural complications
Overdose
|
0.32%
1/310 • Number of events 1 • Long-term safety (i.e. Serious Adverse Events [SAEs]) was collected 6 months to 2 years after the single immunization with VLA1553.
Only new information on ongoing SAEs from the precursor trial VLA1553-301 and new SAEs since the end of the VLA1553-301 trial had to be captured. AEs which did not fulfil the criteria for an SAE did not have to be captured.
|
0.00%
0/53 • Long-term safety (i.e. Serious Adverse Events [SAEs]) was collected 6 months to 2 years after the single immunization with VLA1553.
Only new information on ongoing SAEs from the precursor trial VLA1553-301 and new SAEs since the end of the VLA1553-301 trial had to be captured. AEs which did not fulfil the criteria for an SAE did not have to be captured.
|
|
Injury, poisoning and procedural complications
Pelvic fracture
|
0.32%
1/310 • Number of events 1 • Long-term safety (i.e. Serious Adverse Events [SAEs]) was collected 6 months to 2 years after the single immunization with VLA1553.
Only new information on ongoing SAEs from the precursor trial VLA1553-301 and new SAEs since the end of the VLA1553-301 trial had to be captured. AEs which did not fulfil the criteria for an SAE did not have to be captured.
|
0.00%
0/53 • Long-term safety (i.e. Serious Adverse Events [SAEs]) was collected 6 months to 2 years after the single immunization with VLA1553.
Only new information on ongoing SAEs from the precursor trial VLA1553-301 and new SAEs since the end of the VLA1553-301 trial had to be captured. AEs which did not fulfil the criteria for an SAE did not have to be captured.
|
|
Nervous system disorders
Intracranial aneurysm
|
0.00%
0/310 • Long-term safety (i.e. Serious Adverse Events [SAEs]) was collected 6 months to 2 years after the single immunization with VLA1553.
Only new information on ongoing SAEs from the precursor trial VLA1553-301 and new SAEs since the end of the VLA1553-301 trial had to be captured. AEs which did not fulfil the criteria for an SAE did not have to be captured.
|
1.9%
1/53 • Number of events 1 • Long-term safety (i.e. Serious Adverse Events [SAEs]) was collected 6 months to 2 years after the single immunization with VLA1553.
Only new information on ongoing SAEs from the precursor trial VLA1553-301 and new SAEs since the end of the VLA1553-301 trial had to be captured. AEs which did not fulfil the criteria for an SAE did not have to be captured.
|
|
Nervous system disorders
Seizure
|
0.32%
1/310 • Number of events 1 • Long-term safety (i.e. Serious Adverse Events [SAEs]) was collected 6 months to 2 years after the single immunization with VLA1553.
Only new information on ongoing SAEs from the precursor trial VLA1553-301 and new SAEs since the end of the VLA1553-301 trial had to be captured. AEs which did not fulfil the criteria for an SAE did not have to be captured.
|
0.00%
0/53 • Long-term safety (i.e. Serious Adverse Events [SAEs]) was collected 6 months to 2 years after the single immunization with VLA1553.
Only new information on ongoing SAEs from the precursor trial VLA1553-301 and new SAEs since the end of the VLA1553-301 trial had to be captured. AEs which did not fulfil the criteria for an SAE did not have to be captured.
|
|
Cardiac disorders
Coronary artery disease
|
0.00%
0/310 • Long-term safety (i.e. Serious Adverse Events [SAEs]) was collected 6 months to 2 years after the single immunization with VLA1553.
Only new information on ongoing SAEs from the precursor trial VLA1553-301 and new SAEs since the end of the VLA1553-301 trial had to be captured. AEs which did not fulfil the criteria for an SAE did not have to be captured.
|
1.9%
1/53 • Number of events 1 • Long-term safety (i.e. Serious Adverse Events [SAEs]) was collected 6 months to 2 years after the single immunization with VLA1553.
Only new information on ongoing SAEs from the precursor trial VLA1553-301 and new SAEs since the end of the VLA1553-301 trial had to be captured. AEs which did not fulfil the criteria for an SAE did not have to be captured.
|
|
Gastrointestinal disorders
Abdominal pain upper
|
0.32%
1/310 • Number of events 1 • Long-term safety (i.e. Serious Adverse Events [SAEs]) was collected 6 months to 2 years after the single immunization with VLA1553.
Only new information on ongoing SAEs from the precursor trial VLA1553-301 and new SAEs since the end of the VLA1553-301 trial had to be captured. AEs which did not fulfil the criteria for an SAE did not have to be captured.
|
0.00%
0/53 • Long-term safety (i.e. Serious Adverse Events [SAEs]) was collected 6 months to 2 years after the single immunization with VLA1553.
Only new information on ongoing SAEs from the precursor trial VLA1553-301 and new SAEs since the end of the VLA1553-301 trial had to be captured. AEs which did not fulfil the criteria for an SAE did not have to be captured.
|
|
Hepatobiliary disorders
Cholecystitis
|
0.32%
1/310 • Number of events 1 • Long-term safety (i.e. Serious Adverse Events [SAEs]) was collected 6 months to 2 years after the single immunization with VLA1553.
Only new information on ongoing SAEs from the precursor trial VLA1553-301 and new SAEs since the end of the VLA1553-301 trial had to be captured. AEs which did not fulfil the criteria for an SAE did not have to be captured.
|
0.00%
0/53 • Long-term safety (i.e. Serious Adverse Events [SAEs]) was collected 6 months to 2 years after the single immunization with VLA1553.
Only new information on ongoing SAEs from the precursor trial VLA1553-301 and new SAEs since the end of the VLA1553-301 trial had to be captured. AEs which did not fulfil the criteria for an SAE did not have to be captured.
|
Other adverse events
Adverse event data not reported
Additional Information
Results disclosure agreements
- Principal investigator is a sponsor employee
- Publication restrictions are in place