Genomic surveillance
Dr Leandre Murhula Masirika (speaking on behalf of Dr Pacifique Ndishimye) described work in South Kivu in eastern DRC at the start of the outbreak, which made use of genomic sequencing capacity developed through the EDCTP3-funded GREAT-LIFE project. Genomic sequencing identified a cluster of clade-I-like sequences distinct from existing strains. This was subsequently categorised as a novel clade of mpox, Ib.
The genetic changes seen in clade Ib genomes meant that existing PCR-based tools could no longer be used to distinguish clade I and II viral genomes. The team developed new PCR primers to address this issue.
The team also found that the virus was associated with a range of complications, including various eye disorders and reproductive health conditions and adverse birth outcomes. Metagenomic approaches also identified a range of coinfections associated with mpox lesions.
Dr Néhémie Nzoyikorera (National Public Health Institute of Burundi) described an analysis of nearly 100 samples from Burundi, mostly from Bujumbura, the country’s largest city. The sequences were similar to those from DRC clade Ib isolates, suggesting that the Burundi cases were likely the result of imports from DRC.
However, the sequences also contained mutations that were indicative of modification of the genome within human cells, suggesting that sustained human-to-human transmission has been occurring in Burundi.
Mpox in pregnancy
The adverse effects in pregnancy emphasise the need to protect pregnant women against infection. However, the vaccine mostly used to control mpox, MVA-BN, has not been approved for use in such women, due to a lack of safety data. However, no safety issues have been identified for MVA-BN, it is a non-replicating virus, and a related vaccine has been safely used in pregnant women.
Dr Paulina Morales Ruiz (Global Health Institute, Belgium) described the design of the PregInPoxVac study, which is assessing the safety and immunogenicity of MVA-BN in pregnant and breastfeeding women. It is comparing neutralising antibody levels after vaccination during pregnancy or immediately after birth with that seen in adults. It is also monitoring for adverse events. The study is also examining antibody levels in cord blood and breast milk to assess the potential for protection of infants. The trial results should provide regulators with guidance on whether to approve the vaccine for use in pregnant women.
The PregInPoxVac study has included an intensive social science component, described by Dr Marthe Le Prevost (Fondazione Penta ETS, Italy). The pre-trial work has involved workshops with pregnant women, parents and guardians, and influential community members, to provide information about the trial and to understand perceptions and possible barriers to participation. These consultations identified several key issues, including concern about what was done with blood samples and the possible impact of misinformation.
This work led to the adaptation of the trial design, with a community liaison contact appointed to address misinformation about the trial. In addition, participatory research workshops were held, with a local artist working with the project team and local community members to design detailed information materials. Further community engagement is planned during and after the trial.