The third phase 1 clinical trial will examine how safe and effective the ChAdOx1 Mers vaccine is in adults aged 50 to 70.
Mers-CoV, a camel-linked coronavirus first identified in 2012, is much more deadly to infected people than SARS-CoV-2, but also significantly less transmissible.
Up to a third of all Mers infections are believed to be fatal, compared to a fraction of cases in Covid.
Professor Dame Sarah Gilbert at the University of Oxford’s Pandemic Sciences Institute, and developer of the ChAdOx1 Mers vaccine, told The National a shot against Mers is badly needed.
“Mers is a virus with pandemic potential and is on the World Health Organisation’s priority pathogen list. Investing in a vaccine to control Mers could prevent a global pandemic,” she said.
The majority of all known cases of Mers, which originate in dromedary camels, have been linked to the Middle East region.
Since the disease was first detected a decade ago there have been 2,613 confirmed cases, around 84 per cent of which occurred in Saudi Arabia.
But numbers plummeted since their peak in 2015 when there were 492 laboratory-confirmed cases.
In June the disease was detected in a 28-year-old man in Al Ain in the UAE in the first reported case of the virus in 2023.
From December 29, 2021, to October 31, 2022, four cases were reported to the World Health Organisation by Saudi Arabia's Ministry of Health, with no deaths.
There were 19 cases of Mers in 2021, 17 of them in Saudi Arabia and two in the UAE. Eight of the cases that year were fatal.
The WHO considers Mers as a priority infectious disease that requires urgent vaccine research.
The University of Oxford started developing its vaccine against the virus using the ChAdOx1 platform before the Coronavirus pandemic, which paved the way for the rapid development of the institution’s vaccine against Covid-19.
Prof Gilbert said the trial is “an important step” in the development of a vaccine against the virus.
“Prior to the Covid-19 pandemic, we had already tested our ChAdOx1 Mers vaccine in young adults in the UK and Saudi Arabia.
“Those trials provided information that was critical for the rapid development of the Oxford/AstraZeneca 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.”
But she told The National it is difficult to say how long the vaccine will take to develop.
“The development of a new vaccine typically takes several years. Larger clinical trials and other research will be needed to assess whether the vaccine can protect people from illness due to Mers,” she added.
In total, 84 people aged 50 to 70 will participate in the trial in Liverpool, which follows two previous Phase I clinical trials in the UK and Saudi Arabia.
The earlier trials found the vaccine generated a strong immune response against Mers after one dose and was well tolerated by healthy volunteers aged 18 to 50.
This trial will build on earlier results and will examine vaccine safety and immune responses in older people, after one and two doses of the vaccine.
Vaccitech retains commercialisation rights to ChAdOx1 Mers and is collaborating with the University of Oxford and CEPI to develop the vaccine, which uses the same ChAdOx1 platform as the Oxford/AstraZeneca Covid vaccine.
“The world continues to bear witness to the grave danger and devastation that coronavirus threats can bring through the Covid-19 pandemic – and its deadlier viral cousin Mers remains of regional and global concern as highlighted by recent cases in Abu Dhabi and Saudi Arabia,” said Dr Melanie Saville, executive director of vaccine research and development at CEPI, the funder of the trial.
“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.”