MOVIE-TRACE

The challenge

Optimisation of control measures to prevent the spread of mpox, including the newly emerged clade Ib mpox virus, depends on a good understanding of viral transmission. Key issues include the time during which the virus replicates and a patient is infectious, and the virus's infectiousness (how easily it is transmitted to others). The latter is generally characterised by its ‘secondary attack rate’: the proportion of people in contact with a patient who also become infected.

Although these factors were well studied during the global mpox pandemic of 2022–2023, relatively few data are available from sub-Saharan Africa, from groups such as children and women, who were less affected in the global pandemic, and for clade Ib infections. 

The project

The MOVIE-TRACE project team collected important data on mpox virus infections during the global pandemic, characterising the kinetics of viral shedding from a range of tissues during an infection. Infection kinetics differed significantly across tissue compartments, with skin lesions in particular showing virus shedding for extended periods.

Building on this experience, the team is now conducting two complementary studies in the Democratic Republic of the Congo (DRC) to provide similar insights into clade Ib infections.

• MOVIE: To characterise viral kinetics, the MOVIE study will recruit 50 newly diagnosed patients, including women and children, and analyse samples from different tissues (skin, blood, urine and nose/throat) at five time points out to 8 weeks, measuring viral load and generating an estimate of the time to viral clearance.
• TRACE: To assess infectiousness and calculate secondary attack rate, 10 close contacts of each patient will be recruited and followed up to see which go on to develop mpox infections. Comparisons between those who become infected and those who do not could also reveal factors associated with susceptibility to infection.

MOVIE-TRACE is one of nine projects funded through an emergency call for proposals launched in response to the mpox outbreak in the DRC and other sub-Saharan African countries, which was declared a Public Health Emergency of International Concern (PHEIC) by WHO and a Public Health Emergency of Continental Security (PHECS) by Africa CDC in 2024.

Impact

The MOVIE-TRACE project will provide vital information to inform mpox infection control policies and practices. It will:

• Reveal how long patients are likely to be infectious and therefore need to be kept in isolation.
• Shed light on infectiousness and risks for infection, revealing potentially vulnerable groups and informing targeting of public health responses.
• Generate data on infectiousness that will provide a benchmark for assessing the effectiveness of vaccination.

The results of the MOVIE-TRACE project will therefore feed directly into patient management and the design of disease control strategies and will be a valuable input into trials of mpox interventions.