Phase 3 Infant Safety & Immunogenicity Trial of MVA-BN® in DRC

Summary

This Phase 3 double-blinded, randomized study aims to evaluate the safety and immunogenicity of the two-dose MVA-BN mpox vaccine regimen, administered subcutaneously, in infants and children aged 4 to 24 months in the Democratic Republic of the Congo (DRC), a population at high risk of mpox infection and complications. The study will compare the safety and immunogenicity of a full-dose regimen versus a half-dose regimen in this population. A hierarchical testing strategy will be applied as follows: first, non-inferiority of the full-dose regimen in infants/children (4-24 months old) will be evaluated against the full-dose regimen in adults from the POX-MVA-045 study. If non-inferiority is demonstrated, the immunogenicity of the half dose in infants/children (4-24 months old) will subsequently be tested for non-inferiority vs the full dose in adult. The trial will be conducted in Boende, Tshuapa Province, DRC.

The trial plans to enroll 344 male and female infants/children, who will be randomized to receive two doses of the MVA-BN vaccine administered 28 days apart. Participants in Child Group 1 (N=172) will receive the standard vaccine dose (0.5 mL), while those in Child Group 2 (N=172) will receive half the standard dose (0.25 mL), with both groups following the same dosing schedule.

This study builds on positive safety and immunogenicity data from prior trials that support the use of the standard dose regimen in younger children. However, considering the developmental differences in the immune systems of infants and young children/adolescents, it aims to evaluate whether a half-dose regimen can provide similar immunogenicity while potentially reducing reactogenicity. The findings will offer valuable insights into the optimal dosing strategy for this age group, balancing safety and immunogenicity to inform future vaccination recommendations.

Conditions

• Mpox (Monkeypox)
• Vaccination
• Immunogenicity
• Safety
• Infants
• Children

Interventions

BIOLOGICAL

MVA-BN standard regimen

The MVA-BN vaccine, with the active ingredient: Modified Vaccinia Ankara-Bavarian Nordic, will be administered as a standard two-dose regimen at 1x10\^8 TCID50 Inf.U./0.5 mL. The doses will be given 28 days apart (±3 days) via subcutaneous injection into the deltoid muscle, preferably in the non-dominant arm.

BIOLOGICAL

MVA-BN half-dose regimen

The MVA-BN vaccine, with the active ingredient: Modified Vaccinia Ankara-Bavarian Nordic, will be administered as two half doses of the standard regimen; meaning infants/children allocated to Child Group 2 will receive 0.25 mL of the 0.5 mL. 1x10\^8 TCID50 Inf.U./0.5 mL standard regimen. The doses will be given 28 days apart (±3 days) via subcutaneous injection into the deltoid muscle, preferably in the non-dominant arm. Only one vial will be used per infant/child.

Sponsors & Collaborators

• Ace Africa

  collaborator OTHER

• PENTA Foundation

  collaborator NETWORK

• Bavarian Nordic

  collaborator INDUSTRY

• European and Developing Countries Clinical Trials Partnership (EDCTP)

  collaborator OTHER_GOV

• University of Kinshasa

  collaborator OTHER

• CEPI

  collaborator OTHER

• Jean-Pierre Van geertruyden

  lead OTHER

Study Design

Allocation

RANDOMIZED

Purpose

PREVENTION

Masking

QUADRUPLE

Model

PARALLEL

Eligibility

Min Age

4 Months

Max Age

24 Months

Sex

ALL

Healthy Volunteers

Yes

Timeline & Regulatory

Start

2025-05-29

Primary Completion

2026-06-30

Completion

2027-05-31

Countries

• Democratic Republic of the Congo

Study Locations