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

Summary

This Phase 3 open-label study aims to assess the safety and immune response of the MVA-BN mpox vaccine when administered subcutaneously to pregnant and postpartum women in the Democratic Republic of the Congo (DRC), a population at high risk of mpox infection. The study will be conducted in Boende, Tshuapa Province, DRC.

A total of 359 maternal participants, aged 16 to 35 and in their second or third trimester of pregnancy, will be enrolled. Participants will be randomly assigned to receive two subcutaneous doses of the MVA-BN vaccine, given 28 days apart, either during pregnancy (Maternal Group 1) or within 72 hours after delivery (Maternal Group 2). Additionally, pregnant women in any trimester who have been recently exposed to a confirmed mpox case will be enrolled in the post-exposure prophylaxis (PEP) arm (Maternal Group 3), receiving the vaccine as soon as possible after exposure-ideally within four days but up to 14 days if they remain asymptomatic.

The study will evaluate the safety, reactogenicity, and immune responses of vaccinated pregnant women compared to healthy adults in the POX-MVA-045 study (NCT06549530) through non-inferiority analyses. Participants will be monitored for immunogenicity and safety for 13 months post-delivery, while neonates will be observed for safety over the same period. The trial will also compare outcomes between women vaccinated during pregnancy and those vaccinated postpartum, assess the transfer of maternal immunity to neonates, and explore correlations between maternal antibody levels in serum and breast milk.

This study seeks to provide strong evidence supporting the safety and immunogenicity of the MVA-BN mpox vaccine in pregnancy, contributing to global public health efforts to protect at-risk women and their infants in mpox-endemic regions.

Conditions

• Neonate
• Maternal Transmission
• Mpox
• Vaccination
• Immunogenicity
• Safety
• Pregnancy
• Postpartum

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 standard regimen (Administered as PEP)

MVA-BN. Post Exposure Prophylaxis (PEP) 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. For Maternal Group 3, MVA-Bn will be administered as PEP as soon as possible after exposure, preferably within 4 days after exposure. However, as per WHO guidelines, PEP will be offered up to 14 days after exposure if the pregnant woman has not yet developed symptoms.

Sponsors & Collaborators

• PENTA Foundation

  collaborator NETWORK

• Ace Africa

  collaborator OTHER

• European and Developing Countries Clinical Trials Partnership (EDCTP)

  collaborator OTHER_GOV

• Bavarian Nordic

  collaborator INDUSTRY

• University of Kinshasa

  collaborator OTHER

• Jean-Pierre Van geertruyden

  lead OTHER

Principal Investigators

• Jean Pierre Van geertruyden Van geertruyden, Prof. Dr · Universiteit Antwerpen

Study Design

Allocation

RANDOMIZED

Purpose

PREVENTION

Masking

NONE

Model

PARALLEL

Eligibility

Min Age

16 Years

Max Age

35 Years

Sex

FEMALE

Healthy Volunteers

Yes

Timeline & Regulatory

Start

2025-06-23

Primary Completion

2026-06-30

Completion

2027-05-31

Countries

• Democratic Republic of the Congo

Study Locations