Results Intended to Support Filing for Potential Label Extension for Use in Adolescents

Saint-Herblain (France), May 13, 2024Valneva SE (Nasdaq: VALN; Euronext Paris: VLA), a specialty vaccine company, today reported further positive pivotal Phase 3 data in adolescents for its single-shot chikungunya virus (CHIKV) vaccine. Following the initial analysis up to Day 29 post-vaccination, the most recent analysis of study VLA1553-321 evaluated the safety and immunogenicity six months (Day 180) after vaccination with a single dose of the vaccine. The Day 180 results confirm the initial positive immunogenicity and safety data Valneva reported previously[1],[2], and are intended to support filing for potential label extension for use in adolescents aged 12 to 17 years. The data are also expected to support licensure of IXCHIQ® in Brazil, which would be the first potential approval for use in endemic populations.

The latest VLA1553-321 data confirmed that a single-dose vaccination with VLA1553 induced a high, sustained immune response with a seroresponse rate of 99.1% (232 out of 234 participants) at Day 180 compared to 98.8% (248 out of 251 participants) at Day 29 in an immunogenicity subset of individuals who were CHIKV negative at baseline.

Geometric mean antibody titers (GMTs) consistently surpassed the seroresponse threshold defined with the U.S. Food and Drug Administration (FDA)[3] as the surrogate of protection in baseline seronegative participants who received a single dose of VLA1553.

Additionally, the Day 180 data confirmed that a single dose of the vaccine was generally safe and well tolerated in adolescents receiving VLA1553, irrespective of previous infection with the chikungunya virus. Throughout the trial, an Independent Data Safety Monitoring Board (IDSMB) consistently assessed safety data and found no safety issues. The majority of solicited adverse events observed following VLA1553 administration were mild or moderate and resolved within three days post vaccination.

Juan Carlos Jaramillo M.D., Chief Medical Officer of Valneva, said, “We are highly encouraged by these data, as they reinforce the strong immunity and safety observed in adults and the elderly, upon which FDA approval was granted. Given the substantial risk that chikungunya presents to individuals residing in or traveling to endemic regions, it’s imperative to ensure the vaccine is available to all age groups. This broader accessibility can help provide protection and mitigate the burden of this debilitating illness.”

Conducted in collaboration with Instituto Butantan in Brazil and funded by the Coalition for Epidemic Preparedness Innovations (CEPI) with support from the European Union’s Horizon 2020 program, the VLA1553-321 trial represents the first clinical trial conducted in an endemic area and with individuals previously infected with CHIKV.

Valneva’s vaccine IXCHIQ® is the world’s first and only licensed chikungunya vaccine available to address this significant unmet medical need. It was approved by the U.S. FDA in November 2023[4], and the Centers for Disease Control and Prevention (CDC) recently adopted the Advisory Committee on Immunization Practices’ (ACIP) recommendations on use of the vaccine in the U.S.[5]. Three marketing applications are currently under review by the European Medicines Agency, Health Canada and the Brazilian Health Regulatory Agency (ANVISA) with potential approvals in 2024. IXCHIQ®’s final pivotal Phase 3 data were published in The Lancet, the world’s leading peer-reviewed medical journal, in June 2023[6].

About Phase 3 Study VLA1553-321
VLA1553-321 is a prospective, double-blinded, multicenter, randomized, placebo-controlled pivotal Phase 3 trial conducted in 754 adolescents aged 12 to 17 years old in Brazil. The VLA1553-321 clinical trial was initiated in January 2022 and Valneva reported initial immunogenicity and safety data in November[7] and August 2023[8], respectively. VLA1553 or placebo was administered as a single intramuscular immunization to participants who were randomized into two study groups at a 2:1 ratio. The primary objective is to evaluate the immunogenicity and safety of the adult dose of VLA1553 in adolescents 28 days following a single vaccination. Secondary objectives of the trial include assessment of safety and immunogenicity up to twelve months following a single vaccination with VLA1553. Additional information, including a detailed description of the study design, eligibility criteria and investigator sites, is available at (Identifier: NCT04650399).

About Chikungunya
Chikungunya is a mosquito-borne viral disease caused by the chikungunya virus (CHIKV), a Togaviridae virus, transmitted by Aedes mosquitoes. Infection leads to symptomatic disease in up to 97% of humans after four to seven days following the mosquito bite[9]. While mortality with CHIKV is low, morbidity is high, and the global market for vaccines against chikungunya is estimated to exceed $500 million annually by 2032[10]. Clinical symptoms include acute onset of fever, debilitating joint and muscle pain, headache, nausea, rash and chronic arthralgia. The Chikungunya virus often causes sudden large outbreaks with high attack rates, affecting one-third to three-quarters of the population in areas where the virus is circulating. The high-risk areas of infection for travelers are places where chikungunya virus-carrying mosquitos are endemic, including the Americas, parts of Africa, and Southeast Asia, and the virus has spread to more than 110 countries[11]. Between 2013 and 2023, more than 3.7 million cases were reported in the Americas[12] and the economic impact is considered to be significant. The medical and economic burden is expected to grow as the CHIKV primary mosquito vectors continue to spread geographically. Before IXCHIQ®, there were no preventive vaccines or effective treatments available and, as such, chikungunya is considered to be a major public health threat.

To make the vaccine more accessible to Low- and Middle-Income Countries (LMIC), Valneva and Instituto Butantan in Brazil signed an agreement in January 2021 for the development, manufacturing and marketing of VLA1553[13]. The collaboration falls within the framework of the agreement signed between CEPI and Valneva in July 2019[14], which provides funding of up to $24.6 million with support from the European Union’s Horizon 2020 program. Regulatory review by the Brazilian authority ANVISA is ongoing.

In the U.S., IXCHIQ® is a live-attenuated vaccine indicated for the prevention of disease caused by chikungunya virus (CHIKV) in individuals 18 years of age and older who are at increased risk of exposure to CHIKV. As for all products approved under FDA’s accelerated approval pathway, continued approval for this indication is contingent upon verification and description of clinical benefit in confirmatory studies.

Please click here for full Prescribing Information for IXCHIQ®.

About Valneva SE
We are a specialty vaccine company that develops, manufactures, and commercializes prophylactic vaccines for infectious diseases addressing unmet medical needs. We take a highly specialized and targeted approach, applying our deep expertise across multiple vaccine modalities, focused on providing either first-, best- or only-in-class vaccine solutions.

We have a strong track record, having advanced multiple vaccines from early R&D to approvals, and currently market three proprietary travel vaccines as well as certain third-party vaccines leveraging our established commercial infrastructure.

Revenues from our growing commercial business help fuel the continued advancement of our vaccine pipeline. This includes the only Lyme disease vaccine candidate in advanced clinical development, which is partnered with Pfizer, as well as vaccine candidates against the Zika virus and other global public health threats.

Valneva Investor and Media Contacts
Laetitia Bachelot-Fontaine
VP Global Communications & European Investor Relations
M +33 (0)6 4516 7099

Joshua Drumm, Ph.D.
VP Global Investor Relations
M +001 917 815 4520

Forward-Looking Statements
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[1] Valneva Reports Positive Pivotal Phase 3 Immunogenicity Data in Adolescents for its Single-Shot Chikungunya Vaccine Candidate

[2] Valneva Reports Positive Initial Phase 3 Safety Data in Adolescents for its Single-Shot Chikungunya Vaccine Candidate

[3] Defined as µPRNT50 antibody titer ≥ 150 agreed with the FDA as surrogate of protection to support accelerated approval

[4] Valneva Announces U.S. FDA Approval of World’s First Chikungunya Vaccine, IXCHIQ® – Valneva

[5] ACIP Vaccine Recommendations and Schedules | CDC

[6] Safety and immunogenicity of a single-shot live-attenuated chikungunya vaccine: a double-blind, multicentre, randomised, placebo-controlled, phase 3 trial – The Lancet

[7] Valneva Reports Positive Pivotal Phase 3 Immunogenicity Data in Adolescents for its Single-Shot Chikungunya Vaccine Candidate

[8] Valneva Reports Positive Initial Phase 3 Safety Data in Adolescents for its Single-Shot Chikungunya Vaccine Candidate

[9] Staples, J.E. Hills, S.L. Powers, A.M. “Chikungunya.” In CDC Yellow Book 2020: Health Information for International Travel, by Centers for Disease Control and Prevention. New York: Oxford University Press, 2020

[10] VacZine Analytics Chikungunya virus vaccines Global demand analysis. February 2020


[12] PAHO/WHO data: Number of reported cases of chikungunya fever in the Americas (Cumulative Cases 2018-2023 and Cases per year 2013-2017). Last accessed 01 Aug 2023.

[13] Valneva and Instituto Butantan Sign Final Agreement on Single-Shot Chikungunya Vaccine for Low and Middle Income Countries

[14] CEPI awards up to $23.4 million to Valneva for late-stage development of a single-dose Chikungunya vaccine