Vaccine company Valneva SE has shared positive results of its VLA1553 vaccine against chikungunya in adolescents. This progress, supported by SEPI – A foundation that seeks to accelerate the development of vaccines to combat emerging pandemics — and the European Union — aims to expand use of a vaccine already approved in the United States for adults.

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Valneva SE, a biotechnology company focused on vaccine development, recently announced promising results for its chikungunya virus vaccine VLA1553. These results come from Phase 3 of their study focused on adolescents, and add to preliminary safety data published in August 2023.

Expand vaccine to adolescent population

This project is funded by the Coalition for Epidemic Preparedness Innovations (CEPI) Coalition for Epidemic Preparedness Innovations, in English) and is carried out in collaboration with the Butantan Institute in Brazil, supported by the European Union’s Horizon 2020 programme. The study, named VLA1553-321, targets adolescents and aims to expand authorization for use of the vaccine for this age group.

This approach follows the recent approval of the vaccine for adults Food and Drug Administration (FDA) in the United States. This approval of the vaccine in the United States is based on a Phase 3 study conducted on more than 4,000 adults. The results of these studies are expected to be published in 2022 and 2023, confirming the effectiveness and safety of the vaccine. These data, along with positive results on batch stability and antibody persistence over twelve months, were instrumental in obtaining regulatory approval.

In Europe, preliminary safety data were included in a document submitted to the European Medicines Agency (EMA) in October 2023.

promising results

The study showed that a single administration of VLA1553 produced a strong immune response in adolescents aged 12 to 18 years. These results confirm the effectiveness of the vaccine previously seen in adults.

The primary endpoint of the trial was met, with 98.8% of participants developing protective antibodies 28 days after vaccination. This performance far exceeds FDA requirements, which set a seroconversion rate greater than 70% for a study to be considered successful.

The vaccine showed high immunogenicity, with levels of neutralizing antibodies in adolescents comparable to those seen in adults who have already been infected with the virus. The tolerability of VLA1553 was generally good in adolescents, whether or not they were previously infected with chikungunya, similar to the safety profile seen in adults.

The trial involved 754 adolescents, of whom data was collected from 29I Day after vaccination. An independent safety data monitoring board reviewed the data regularly throughout the trial, without identifying any major safety concerns. Most of the adverse reactions observed were mild or moderate and resolved within a few days.

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