Chikungunya is a mosquito-borne viral infection spreading in the Americas and Europe, caused by the chikungunya virus (CHIKV), a Togaviridae virus transmitted by Aedes mosquitoes. Between 2013 and 2023, more than 3.7 million cases were reported in the Americas and the economic impact is considered to be significant1. The medical and economic burden is expected to grow as the CHIKV primary mosquito vectors continue to spread geographically.

VLA1553 – Valneva’s single-shot chikungunya vaccine candidate

  • VLA1553 is a live-attenuated, single dose investigational vaccine candidate targeting the chikungunya virus, which has spread to over 110 countries. It has been designed by deleting a part of the chikungunya virus genome.
  • VLA1553 received U.S. FDA approval2 in November 2023 under the brand name IXCHIQ®. The vaccine is indicated in the U.S. for the prevention of disease caused by 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 of clinical benefit in confirmatory studies.
  • In February 2024, the U.S. Advisory Committee on Immunization Practices (ACIP) developed recommendations on how to use the vaccine in the U.S and these recommendations were then adopted by the U.S. Centers for Disease Control and Prevention.
  • Final pivotal Phase 3 data in 4,115 adults, aged 18 years and above were published in The Lancet, the world’s leading peer-reviewed medical journal, in June 20234. The article provides a detailed analysis of the Phase 3 results showing that VLA1553 demonstrated a very high seroresponse rate of 98.9% in participants 28 days after receiving a single dose of the vaccine.
  • Earlier clinical data, published in the Lancet Infectious Diseases, showed a rapid onset of immune response with a single dose of VLA1553 between 7- and 14-days post-vaccination5. This was later confirmed in a further analysis of the Phase 1 data, which showed that 100% of vaccinated individuals reached the immune threshold established with the FDA at day 146.
  • Additionally, VLA1553 was able to demonstrate a robust immune response which was sustained for 12 and 24 months by 99% and 97% of participants, respectively, and was equally durable in younger and older adults8,9. This dedicated antibody persistence trial (VLA1553-303) will continue to evaluate persistence for a period of at least five years.
  • A clinical study in adolescents, VLA1553-321, is ongoing in Brazil10, for which Valneva reported initial safety data in August 2023 and further positive pivotal data in May 202411. The data 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.
  • To make VLA1553 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 VLA155312. The collaboration falls within the framework of the agreement signed between CEPI and Valneva in July 2019, which provides funding of up to $24.6 million with support from the European Union’s Horizon 2020 program13.
  • Additionally, the Company initiated a Phase 2 pediatric trial in children aged 1 to 11 years, VLA1553-221, in January 202414 to support a Phase 3 pivotal pediatric study and potentially extend the label to this age group following initial regulatory approvals in adults and possibly in adolescents.

Additional information about chikungunya:

Additional information about VLA1553, including information about safety, is available in Valneva’s prior press releases and in the IXCHIQ® prescribing information, which is available on the FDA’s website.

Valneva’s press releases about VLA1553

[1] 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.

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

[3] Valneva Announces Publication of its Chikungunya Vaccine Candidate Phase 3 Data in The Lancet

[5] Wressnigg N, Hochreiter R, Zoihsl O, Fritzer A, Bézay N, Klingler A, Lingnau K, Schneider M, Lundberg U, Meinke A, Larcher-Senn J, Čorbic-Ramljak I, Eder-Lingelbach S, Dubischar K, Bender W. “Single-shot live-attenuated chikungunya vaccine in healthy adults: a phase 1, randomised controlled trial.” Lancet ID, 2020: 20(10):1193-1203.

[6] McMahon R, Töpfer S, Schneider M, Hadl S, Hochreiter R, Kosulin K, Mader R, Zoihsl O, Wressnigg N, ​Dubischar K, Buerger V, Eder-Lingelbach S, Jaramillo JC. “One year antibody persistence and safety of a live-attenuated chikungunya virus (CHIKV) vaccine candidate (VLA1553) in adults aged 18 years and above.” CISTM. Basel, 2023.

[8] Valneva Reports Positive 12-Month Antibody Persistence Data for Single-Shot Chikungunya Vaccine Candidate – Valneva

[9] Valneva Reports Positive 24-Month Antibody Persistence Data for its Single-Shot Chikungunya Vaccine IXCHIQ® – Valneva

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

[11] Valneva Reports Further Positive Pivotal Phase 3 Data in Adolescents for its Single-Shot Chikungunya Vaccine

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

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

[14] Valneva Vaccinates First Participant in Pediatric Trial of Single-Shot Chikungunya Vaccine – Valneva