Home›Drug Pipeline› VLA1553 Chikungunya Vaccine Maintains 94.5% Seroresponse at 4 Years
VLA1553 Chikungunya Vaccine Maintains 94.5% Seroresponse at 4 YearsTrial Shows VLA1553 Vaccine Maintains Protection Against Chikungunya Virus
Human vaccines & immunotherapeuticsPublished September 20, 2026Study authors: Sattler Natascha, Scheiblauer Susanne, Hochreiter Romana, Kosulin Karin, Buerger VeraPubMed ↗DOI ↗Editorial oversight: Dr. Julia Lee, PhD · Oncology, Genomics & Drug Development
AI-generated summary of the cited source, checked by automated accuracy review.
How we work
Share
Key Takeaway
Interpret 4-year VLA1553 antibody persistence cautiously; it is a surrogate endpoint from a single-arm study.
This single-arm observational study followed 254 adults, predominantly White and without Hispanic or Latino background, for 4 years after a single dose of VLA1553, a chikungunya vaccine candidate. The primary outcome was antibody persistence, and the secondary outcome was seroresponse rate.
At 4 years, 240 of 254 participants (94.5%, 95% CI 90.9% to 97.0%) maintained seroresponse. Day 29 geometric mean titers (GMTs) remained above the threshold of 150 at each annual assessment: 1056 at Year 1, 785 at Year 2, 737 at Year 3, and 589 at Year 4. Antibody persistence in adults aged 65 years and older was similar to that in younger adults.
Safety data, including adverse events, serious adverse events, discontinuations, and tolerability, were not reported. The study was limited by its single-arm design, and no comparator was reported. Funding and conflicts of interest were not reported.
The findings suggest that VLA1553 elicits neutralizing antibody titers that persist above the defined seroresponse threshold for at least 4 years. However, the seroresponse threshold is a surrogate endpoint, and clinical benefit has not been established. These results should be interpreted with caution given the observational, single-arm design and the absence of safety reporting.
How this fits prior evidence
This 4-year antibody persistence finding extends prior coverage of chikungunya by providing longer-term immunogenicity data for a vaccine candidate, whereas a prior narrative review noted a lack of specific clinical data. It also complements an observational study that evaluated clinical prediction models for arbovirus surveillance and a meta-analysis that associated maternal chikungunya infection with adverse pregnancy outcomes. The current study does not address musculoskeletal pathology or environmental drivers covered previously, and it uses a surrogate endpoint rather than clinical outcomes.
Researchers conducted a clinical trial to see how well a single dose of the VLA1553 vaccine works against the Chikungunya virus. The study included 254 adults. The main goal was to see if the vaccine could create lasting antibodies that stay in the body over time.
The results showed a 94.5% seroresponse rate among the participants. Importantly, the study found that antibody levels remained well above the required threshold for at least four years. This means the vaccine provided lasting protection in the body for a long period after just one dose.
One important finding was that older adults aged 65 and over showed similar antibody levels to younger adults. While the study is a single-arm trial and uses a laboratory marker to predict protection, the data suggests the vaccine is durable. You should talk with a healthcare provider to see how this vaccine fits into current prevention plans.
What this means for you:
A single dose of VLA1553 showed lasting antibody levels against Chikungunya for at least four years.
Common questions
How long does the protection from the VLA1553 vaccine last?
The study found that the vaccine produced antibody levels that stayed well above the required threshold for at least four years. This suggests that a single dose can provide long-lasting protection in the body for several years.
Is the vaccine effective for older adults?
Yes, the study found that adults aged 65 and older showed antibody levels similar to those of younger adults. This indicates the vaccine's response was consistent across different age groups in the study.
What was the success rate for the vaccine in the study?
The study reported a seroresponse rate of 94.5% among the 254 participants. This means the vast majority of people who received the single dose developed the expected antibody response.
VLA1553 is a live-attenuated chikungunya virus vaccine approved for active immunization, in the EU, Brazil, Canada and the UK, as a prophylactic measure for individuals travelling to or living in areas where the chikungunya virus is circulating. Due to the unpredictable epidemic occurrence of chikungunya, a 50% micro-plaque reduction neutralization test titre (μPRNT) of ≥150, was previously accepted by regulators as an immunological surrogate endpoint that is reasonably likely to predict clinical benefit. At this point in time, this phase 3b open-label, single-arm long-term focuses on antibody persistence in a subset (N = 363) of VLA1553 vaccinees from a pivotal phase 3 trial (Schneider et al., 2023) where 4115 adult participants received VLA1553 or placebo. At Year 4, 254 participants remained in follow-up with slightly more females than males. The population is predominantly White with no Hispanic or Latino background. The seroresponse rate was 94.5% (240/254, 95% CI 90.9% to 97.0%). The Day 29 GMT for the long-term follow-up cohort was 3542, and remained high with 1056 at Year 1, 785 at Year 2, 737 at Year 3 and 589 at Year 4, considerably exceeding the seroresponse threshold of 150. In adults aged ≥65 years, antibody persistence was similar to younger adults throughout the follow-up. Single dose vaccination with our live-attenuated chikungunya virus vaccine VLA1553 resulted in persistent neutralizing antibody titers well above the defined seroresponse threshold for at least 4 years.
