Efficacy of camel vaccination and behavioural intervention for MERS-CoV prevention in high-risk camel-owning households: a randomised controlled trial

Middle East respiratory syndrome coronavirus (MERS-CoV) is one of three deadly zoonotic betacoronaviruses to emerge globally in the past two decades. The first known MERS outbreak occurred in a hospital in Jordan in 2012. Since then, as of May 2025, a total of 2,638 cases and 957 deaths have been reported, most of them in the Arabian Peninsula. With a high case fatality rate and ongoing zoonotic transmission, MERS-CoV remains a significant public health threat and is classified by the World Health Organisation (WHO) as a priority pathogen, given its potential for large-scale outbreaks and pandemic risk. In Jordan, MERS-CoV is a recognized One Health priority by both the Ministry of Health (MoH) and the Ministry of Agriculture (MoA). This project addresses a key evidence gap by evaluating two interventions: behavioural changes and camel vaccination to reduce zoonotic MERS-CoV transmission within high-risk camel-owning households in Jordan. The study uses a randomized factorial design to evaluate the protective effects of a behavioural intervention package and camel vaccination, both separately and in combination. The behavioural intervention, which has been recently piloted successfully, promotes safer camel-handling practices, improved hygiene, and management of comorbidities, while the camel vaccination employs the MVA-MERS-S vaccine, which has been shown to reduce viral shedding in camels and to protect against camel pox. A registry of camel-owning households maintained by Jordan's MoA will be used to recruit 700 households to randomise into the four trial arms including a control arm. Outcome measurement will include RT-qPCR testing of nasal swabs in household members, observational assessments of behaviour as well as process measures. The primary outcome will be the reduction in positive MERS-CoV RT-qPCR of nasal swabs. In addition, the trial will assess viral shedding and serological responses in camels as secondary outcomes, providing further evidence of vaccine impact and field performance. The project builds on a decade-long partnership between institutions in the UK, Jordan, and the US, combining expertise in epidemiology, virology, anthropology and community-based interventions. Our team was the first to identify MERS-CoV in dromedary camels in Jordan, providing evidence of its zoonotic transmission and identifying risk factors in both camels and humans. More recently, in a pilot trial evaluating behavioural changes to mitigate MERS-CoV exposure, our team conducted systematic community-based RT-qPCR testing of respiratory samples from members of high-risk camel-owning households, detecting multiple asymptomatic infections prior to any intervention. Despite their considerable potential, robust trials of interventions in animals to protect humans are rare. In line with One Health principles and the WHO's emphasis on integrated strategies to tackle health risks at the human-animal interface, this project represents such an approach. The anticipated outcomes are to provide actionable evidence to support the sustainable deployment of interventions in Jordan and other high-risk settings. The project prioritizes responsible research practices, including community engagement, co-leadership with Jordanian researchers, and local capacity building, ensuring interventions are culturally appropriate and sustainable. We partner with the World Organization for Animal Health (WOAH) and the Food and Agriculture Organization of the United Nations (FAO) underscoring the project's alignment with both regional and international priorities and enhancing its potential for scalability and broader implementation. This research will not only provide critical evidence to mitigate MERS-CoV transmission and strengthen global health security but also serve as a model for addressing zoonotic diseases through integrated human-animal health approaches.