Valneva has announced the completion of subject enrolment and vaccination for the Phase III VLA1553-321 adolescent trial of VLA1553 for chikungunya.

Initial results from the double-blinded, multi-centre, randomised, placebo-controlled trial are expected in the middle of this year.

The VLA1553-321 adolescent trial is funded by the Coalition for Epidemic Preparedness Innovations (CEPI) and is intended to support the label extension in adolescents after potential initial regulatory approval from the US Food and Drugs Administration (FDA) in adults.

It is also expected to support the licensure of the single-shot chikungunya vaccine candidate VLA1553 in Europe and Brazil.

The Phase III trial is carried out in partnership between Instituto Butantan and Valneva.

In this trial, 754 adolescents aged 12 to 17 years were randomised in a 2:1 ratio to receive either VLA1553 or a placebo.

The trial’s primary objective is to assess safety and immunogenicity 28 days after a single vaccination with VLA1553.

Subjects will be assessed for the primary endpoint and followed up after 12 months.

Additionally, the trial will provide the first systematic immunogenicity and safety data in subjects who were exposed to chikungunya earlier.

Valneva chief medical officer Juan Carlos Jaramillo said: “Recruitment completion in this study is an important milestone for the overall programme.

“We reported compelling pivotal Phase III results in adults and in the elderly, and we are now looking forward to obtaining results in adolescents later this year.”

In December last year, Valneva completed the rolling submission of the Biologics License Application (BLA) for obtaining the FDA approval of VLA1553 in individuals aged 18 years and older.

It is expected to become the first chikungunya vaccine to be marketed in the US, once the BLA filing is accepted and approved.

Last May, Valneva completed the lot-to-lot Phase III consistency trial of VLA1553 for chikungunya.