In September 2023 the University of Oxford’s Pandemic Sciences Institute (PSI) announced that a Phase I clinical trial for a vaccine against Middle East Respiratory Syndrome (MERS) had launched. This is the third Phase I clinical trial of the ChAdOx1 MERS vaccine but the first in older patients. The trial, led by the University of Oxford’s Oxford Vaccine Group, is funded by CEPI. It will be delivered by the Liverpool School of Tropical Medicine and the Liverpool University Hospitals NIHR Liverpool Clinical Research Facility and Royal Liverpool University Hospital. Vaccitech plc is collaborating with the University of Oxford and CEPI to develop the vaccine.  


MERS is a viral respiratory illness caused by MERS coronavirus (MERS-CoV). It is from the same viral family as COVID-19. WHO suggests that typical symptoms include fever, cough, and shortness of breath, with pneumonia also being common. Gastrointestinal symptoms have also been reported. Up to 35% of MERS cases result in death.  

It is a zoonotic virus, with human infections linked to dromedary camels in parts of the Middle East, Africa, and South Asia. It was first identified in Saudi Arabia in 2012 and is one of WHO’s priority infectious diseases. There are currently no approved vaccines or treatments.  


The University of Oxford was working on a vaccine against MERS using the ChAdOx1 platform before the COVID-19 pandemic began. PSI suggests that this research “paved the way” for the rapid development of the Oxford/AstraZeneca vaccine 2020.  

“This underlines the need for continued global funding and focus on vaccine development for lesser-known diseases.” 

84 people between the ages of 50 and 70 will take part in the trial in Liverpool, following two Phase I clinical trials in the UK and Saudi Arabia. Professor Dame Sarah Gilbert at the University of Oxford’s Pandemic Sciences Institute believes the trial is an “important step”. It follows the previous trials that “provided information that was critical for the rapid development” of a COVID-19 vaccine. 

“We are now returning to the task of developing a vaccine against MERS, and for the first time will test it in older adults, which is the age group most in need of protection against this life-threatening virus.”  

The previous trials found the vaccine generated a “strong immune response” after one dose; it was “well tolerated” by healthy volunteers between the ages of 18 and 50. The latest trial will build on these results and examine safety and immune responses in older people.  

Regional and global need 

Dr Melanie Saville, CEPI’s Executive Director of Vaccine Research and Development, commented that the world “continues to bear witness to the grave danger and devastation” of coronavirus threats through the COVID-19 pandemic. However, MERS is a “deadlier viral cousin” that remains of “regional and global concern”.  

“This latest Phase I trial of Oxford’s MERS vaccine, developed on the ChAdOx1 platform – one of only a few clinically validated rapid-response platforms globally – is of particular importance as the findings will provide critical guidance on how we can better protect vulnerable communities from the health and socioeconomic impact of this deadly pathogen.”  

Professor Maheshi Ramasamy, Clinician Scientist at the Oxford Vaccine group and Chief Investigator of the trial, agreed that “MERS has a higher fatality rate than COVID-19″.  

“This trial is an exciting opportunity to build on our partnership with Liverpool, developed during the Oxford COVID-19 vaccine trials, to investigate a promising vaccine against another potentially lethal coronavirus.”  

Dr Andrea Collins, Senior Clinical Lecturer in Respiratory Medicine at Liverpool School of Tropical Medicine and Principal Investigator for the trial is “excited” to deliver it.  

“We have a database of amazing volunteers in Liverpool stepping forward to participate just like they did during the COVID-19 pandemic. We couldn’t do this without them, so thank you to every one of them.” 

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