VLA1553 Chikungunya Virus Vaccine Shows Antibody Persistence Up to 2 Years Following Administration

The investigators of the phase 3b trial (NCT04838444) will continue to follow up with patients for up to 10 years.

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About the Trial

Trial Name: Antibody Persistence And Long Term Safety Of A Chikungunya Virus Vaccine (VLA1553)

ClinicalTrials.gov ID: NCT04838444

Sponsor: Valneva Austria GmbH

Completion Date (Estimated): May 2031

Results from a phase 3b trial (NCT04838444) indicate that vaccination with VLA1553 (Valneva Austria GmbH) is a safe, efficient intervention that offers high seroprotection against infection from the chikungunya virus. Additionally, there were no long-term serious adverse events (SAEs) related to vaccination among the patient population.¹

Chikungunya virus disease is caused by the chikungunya virus, which is present in Africa, Asia, parts of Europe, and the Americas. It is transmitted by the bites of mosquitoes infected with the virus, and the disease is characterized by both acute and chronic stages. Mild symptoms can include rash, headache, and muscle pain, and acute symptoms often including higher fever, intense myalgia, and polyarthralgia. Approximately 43% of individuals who are infected experience chronic and debilitating symptoms, such as arthralgia, which can persist for months and up to years after initial infection.^1,2

In November 2023, VLA1553 (Ixchiq; Valneva Austria GmbH) received FDA-approval for chikungunya disease, and was the first vaccine to be approved for this disease. It is indicated for patients who are 18 years and older and are at risk of exposure to chikungunya virus. The vaccine contains a live, weakened version of the chikungunya virus and is administered as a single dose intramuscularly. The FDA approval came after 2 clinical trials in which VLA1553 demonstrated immune response compared with placebo.²

The current clinical trial (NCT04838444) is a single-arm, open-label, phase 3b trial that evaluated the persistence of antibodies as well as long-term safety in 375 enrolled participants rolled over from the double-blind, randomized, placebo-controlled phase 3 VLA1553-301 clinical trial (NCT04546724). All participants received 1 dose of VLA1553 and will attend follow-up visits for up to 10 years following vaccination. The trial’s primary objective is the persistence of antibodies annually from 1 to 10 years post-immunization, and the secondary objective is long-term safety at 6 months to 2 years.^1,3

After a single vaccination of VLA1553, chikungunya virus-neutralizing antibodies above the threshold demonstrated persistence in patients, with a high proportion of individuals maintaining protective titers up to 2 years after vaccination. Seroprotection rates were nearly at or above 97% at the 1-year (98.9% [356 of 360 assessable participants; 97.2%–99.7%]) and 2-year (96.8% [306 of 316; 94.3%–98.5%]) follow-ups, according to the investigators. These findings were independent of age group and were very similar between those aged 18 to 64 years ( at 1 year follow up: 98.7% [303 of 307; 96.7%–99.6%]; at 2 year follow up: 96.6% [256 of 265; 93·7–98·4]) and those aged 65 years and older (1 year follow up: 100% [53 of 53; 93.3%–100%]; 2 year follow up: 98.0% [50 of 51; 89.6%–100%]).¹

Additionally, there were no safety concerns regarding long-term SAEs or AEs during the timeframe; however, there were 10 SAEs that occurred in 9 participants (2%) between 6 months and 2 years with 1 death, but this was because of a drug overdose and was deemed unrelated to VLA1553 vaccination. Despite the positive implications of VLA1553, the investigators note that immunogenicity will continue to be monitored for at least 5 years.¹

The investigators emphasize that the high antibody persistence at 2 years post-vaccination is important because of the unpredictable epidemiology of chikungunya virus infection. Notably, the findings may be of particular importance for those traveling internationally. VLA1553 continues to show promise as a chikungunya virus vaccine for the active immunization of those either living in or traveling to endemic areas, according to the investigators.¹

REFERENCES

1. McMahon R, Toepfer S, Sattler N, et al. Antibody persistence and safety of a live-attenuated chikungunya virus vaccine up to 2 years after single-dose administration in adults in the USA: a single-arm, multicentre, phase 3b study. The Lancet Infectious Diseases. 2024. doi:10.1016/S1473-3099(24)00357-8

2. US Food & Drug Administration. FDA Approves First Vaccine to Prevent Disease Caused by Chikungunya Virus. News release. November 9, 2023. Accessed September 11, 2024. https://www.fda.gov/news-events/press-announcements/fda-approves-first-vaccine-prevent-disease-caused-chikungunya-virus

3. Antibody Persistence And Long Term Safety Of A Chikungunya Virus Vaccine (VLA1553). ClinicalTrials.gov identifier: NCT04838444. Updated August 15, 2024. Accessed September 9, 2024. https://clinicaltrials.gov/study/NCT04838444