Mpox Comprehensive Assessment for Responsive Immunisation in Emergency Outbreaks

Cases of Mpox in Central and East Africa have been climbing since December 2022 when Democratic Republic of Congo (DRC) declared a national outbreak of the disease. There are two strains of circulating virus, clade Ia (previously known as clade I) in northwestern DRC primarily affecting children, and a new strain clade Ib in northeastern DRC which has since spread to bordering countries. The clade Ib strain, sub-lineage A was first identified in South Kivu. This strain has been found to have a APOBEC3-type mutations allowing increased circulation between humans. This novel clade is mainly characterized by the gene insertions and deletions including the deletion on C3L gene that effect the CDC recommended Clade I-specific real-time PCR detection. The WHO Director General declared the outbreak a public health emergency on 14th August 202433 as a result of escalating case numbers of both clade I strains. As of 28July 2024, this year there have been a total of 14,250 cases in 10 African countries, with a case fatality of 3.2%. This is likely to be an underestimate given the limited testing and healthcare capacity in some of the regions affected. The clade 1b Mpox outbreak is an urgent public health emergency in need of scientific countermeasures to control the spread of disease and protect African communities.

The primary clinical aim of this study to develop novel immune diagnostics to estimate Mpox's sero-prevalence and determine exposure to Mpox virus and/or previous vaccination as a tool for vaccine prioritization among at risk populations.

Participants will be recruited from the following groups:

• Group 1 (suspected exposure cohort): asymptomatic volunteers at risk of Mpox including:

• Those who live within or adjacent to, or spend prolonged amounts of time in an epidemiologically identified region of Mpox transmission
• Close contacts of those with microbiologically confirmed Mpox
• Group 2 (post-exposure/vaccinated cohort):

• asymptomatic volunteers who have had clinically or microbiologically confirmed Mpox infection within the last one-month (group 2a) or more than one-month ago (group 2b)
• Those who have received a smallpox/MVA vaccine within the last one-month (group 2c) or more than one-month ago (group 2d)
• Group 3 (control cohort): asymptomatic volunteers with no known exposure to Mpox

Inclusion criteria

• Healthy males and females aged between ages 5-80 years, who are able and willing to provide informed consent and will comply with the study requirements.
• Group 1 (suspected exposure cohort) only

• Live within or adjacent to an epidemiologically identified region of Mpox transmission
• Close contacts of those with microbiologically confirmed Mpox
• Group 2 (post-exposure/vaccinated cohort) only

• Previous clinically or microbiologically confirmed Mpox or confirmed previous vaccination with a smallpox/MVA vaccine
• Fully recovered from Mpox infection
• Group 3 (control cohort) only:

• Asymptomatic with no known exposure to Mpox

Exclusion criteria

• Unwilling or unable to provide informed consent to take part
• Unwilling or unable to comply with study procedures
• History of any suspected or confirmed disorder of the immune system that, in the opinion of the investigators, might impair the results of the study
• Have a bleeding disorder deemed significant by a member of the study team
• Pregnant or breast-feeding females
• Group 1 (suspected exposure cohort) only

• Known history of Mpox infection
• Current symptoms consistent with Mpox
• Known exposure to Mpox in the last month
• Group 2 (post-exposure/vaccinated cohort) only

• Participants with any ongoing symptoms of Mpox, indicating incomplete recovery.
• Group 3 (control cohort only)

• Symptoms of Mpox
• Known exposure to Mpox in the last month