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.
Age range
16 Years – 35 Years
Sex
FEMALE
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Main study: Neutralising antibody response post-dose 2 vaccination with MVA-BN
Timeframe: 14 days after the second dose
Safety and reactogenicity of the MVA-BN vaccine in pregnant women
Timeframe: Throughout the trial period; from first vaccination to 13 months postpartum.
Neonatal/infant safety outcomes in offspring of vaccinated mothers
Timeframe: Throughout the trial period; from delivery to 13 months postpartum.
Maternal, fetal, and neonatal outcomes in vaccinated women
Timeframe: From vaccination to 13 months postpartum
Sub-study. Maternal immunity transferred via breastmilk
Timeframe: At delivery
Immunogenicity in maternal serum post-vaccination
Timeframe: Baseline to 13 months postpartum
Maternal immunity transferred via breastmilk (IgA antibodies)
Timeframe: Delivery to 13 months postpartum
Maternal immunity transferred via breastmilk (IgG antibodies)
Timeframe: 6 weeks and 12 weeks postpartum
Persistence of maternal immunity in infants
Timeframe: 6 weeks to 6 months postpartum