The European observational study, MOSAIC, provides evidence on how the clade IIb mpox virus affects patients and the risks of onward transmission
In May 2022, a new variant of the mpox virus caused a global outbreak. This variant, known as clade IIb, differs from the mpox typically seen in Africa, particularly in how it spreads and the symptoms it causes.
To address the limited availability of clinical evidence regarding mpox and of therapeutic options available to patients, ISARIC has implemented a multi-pronged approach, encompassing the development of advanced methodological frameworks and standardised data collection tools, providing support to other research groups, and executing both observational and interventional studies.
Following the 2022 outbreak, the observational study MOSAIC was conducted to better understand the clinical features of the disease and to measure how long it took for skin lesions to heal and for the virus to clear. Data were collected through hospital visits, phone interviews, and self-completed questionnaires over six months of follow-up.
The results of MOSAIC recently published in Clinical Infectious Diseases provide insights into the clinical presentation and clinical and virologic outcomes of a cohort of 575 participants with confirmed mpox virus infection, recruited between May 2022 and July 2023 in six European countries (Belgium, France, Italy, Spain, Switzerland, and the United Kingdom).
Study participants were mostly men aged 30-45 years; nearly half were living with HIV. The majority could be cared for at home without specific treatments and without requiring hospitalisation. Only ten percent received putative antiviral treatment specifically for mpox – shortages in drug supplies meant only few selected patients could be offered those medications. The study design did not allow researchers to fully assess the effectiveness of the antiviral treatments, as it was not designed to compare treated and untreated groups.
Lesions were mostly affecting the skin around the genitals and anus. It took time for lesions to heal and to shed the virus. Importantly, 5% of the participants still had viable virus in skin lesions, which means they can still transmit the infection, 7-8 weeks after testing positive. There were no deaths, and no participants experienced a recurrence of infection within the six-month follow-up period. People living with HIV/AIDS had well-controlled infections and their presentation and outcomes did not differ from participants without HIV infection.
Professor Piero Olliaro, Chief Investigator of MOSAIC, said: ”The evidence generated by this study on how the clade IIb mpox variant affects patients and on risks of onward transmission are useful for case management, public health measures, and personal behaviours.”
The findings of this study underscore the need for further research to improve responses to ongoing outbreaks.
Read the paper in Clinical Infectious Diseases
ISARIC is supporting groups working in Africa and elsewhere to build and sustain clinical research on mpox. This work includes the clinical characterisation protocol (CCP), a standardised Mpox Case Report Form (CRF) template, and analytical tools that were recently used in the First Observational Study on Clade Ib Mpox Transmission and Disease Severity in South Kivu.
