Phase 3 Maternal Safety & Immunogenicity Trial of MVA-BN® in DRC (NCT06844500) | Clinical Trial Compass
Active — Not RecruitingPhase 3
Phase 3 Maternal Safety & Immunogenicity Trial of MVA-BN® in DRC
Democratic Republic of the Congo359 participantsStarted 2025-06-23
Plain-language 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.
Who can participate
Age range16 Years – 35 Years
SexFEMALE
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Inclusion criteria
✓. The participant must be between 16 and 35 years of age inclusive on the consent day.
✓. The participant must pass (≥9/10) the Test of Understanding after being advised of the risks and benefits of the trial in a language understood by the participant and before performing any trial-specific procedures.
✓. The participant must sign and date an informed consent form (≥18 years old) or assent form (16-17 years old) indicating that he or she understands the purpose of and procedures required for the study and is willing to participate in the study.
✓. The participant must be in her second (13-27 weeks) or early third trimester (28-32 weeks) of pregnancy at the time of vaccination.
✓. The participant and her unborn child must be generally healthy in the investigator's clinical judgment and on the basis of vital signs assessed at day 1 screening with no severe (chronic) conditions (as far as medically known) that might interfere with vaccine assessment.
✓. The participant must be pregnant with a singleton pregnancy.
✓. The participant must live in the Boende health zone or its surrounding health zones in the Tshuapa province of the DRC.
✓. The participant must be willing to deliver her child to the General Referral Hospital of Boende (the trial site location) or the satellite sites Motema Mosantu Health Centre or Marie-Louse Health Centre or the participant must be willing to inform the study staff when labour has started (either through the GRH or satellite site staff, through family or via mobile phone).
What they're measuring
1
Main study: Neutralising antibody response post-dose 2 vaccination with MVA-BN
Timeframe: 14 days after the second dose
2
Safety and reactogenicity of the MVA-BN vaccine in pregnant women
Timeframe: Throughout the trial period; from first vaccination to 13 months postpartum.
3
Neonatal/infant safety outcomes in offspring of vaccinated mothers
Timeframe: Throughout the trial period; from delivery to 13 months postpartum.
4
Maternal, fetal, and neonatal outcomes in vaccinated women
Timeframe: From vaccination to 13 months postpartum
5
Sub-study. Maternal immunity transferred via breastmilk
Timeframe: At delivery
6
Immunogenicity in maternal serum post-vaccination
Timeframe: Baseline to 13 months postpartum
7
Maternal immunity transferred via breastmilk (IgA antibodies)
✕. Having received any smallpox or licensed or investigational poxvirus-based (e.g. ACAM2000, MVA-BN based like MVA-BN-Filo) vaccine in the past.
✕. Must not have received another experimental or non-licensed vaccine within 4 weeks before receiving the MVA-BN vaccine and during the trial.
✕. Known allergy or history of anaphylaxis or other severe adverse reactions to vaccines or vaccine products (including any of the constituents of the study vaccines), including known allergy to egg, egg products and aminoglycosides.
✕. History of allergic disease or reactions likely to be exacerbated by any component of the vaccine, e.g., tris(hydroxymethyl)-amino methane, including a history of allergic asthma.
✕. Acute or chronic medical condition that, in the opinion of the investigator, would render the trial procedures unsafe or would interfere with the evaluation of responses, including but not limited to neurologic, cardiovascular, respiratory, hepatic, hematologic, rheumatologic, endocrine, gastrointestinal, renal, autoimmune, or immunosuppressive conditions.
Maternal immunity transferred via breastmilk (IgG antibodies)