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Marburg vaccines are set to arrive in Rwanda in the coming days to help protect healthcare workers fighting an outbreak of the deadly haemorrhagic fever.
The jabs, developed by the Sabin Vaccine Institute initially to treat Ebola, are currently in phase 2 of clinical trials for use against the virus, which has a fatality rate of almost 90 per cent.
They will likely be deployed in a ring vaccination strategy, targeting healthcare workers and others linked to the 410 individuals currently under observation, the country’s health minister Dr Sabin Nsanzimana told a press briefing on Thursday.
It is hoped the approach will not only help to curb the outbreak but also gather valuable data as part of the ongoing trial.
If it goes ahead within the coming days or weeks, it will be a remarkable achievement. In 2022, Uganda set a new record when it rolled out the first doses of a candidate Ebola virus vaccine just 79 days after an outbreak was declared. Rwanda only declared its outbreak on September 27 – seven days ago.
‘This is a very aggressive virus’
The haemorrhagic fever has now killed 11 people in Rwanda, with at least 25 more patients – predominantly healthcare workers – still fighting for their lives in isolation units.
But according to the World Health Organization (WHO), the first person infected died on September 8. The patient also tested positive for malaria, which delayed the identification of Marburg and helps to explain why so many cases have been confirmed since the Ministry of Health announced the outbreak last week.
Although symptoms typically develop between two or three days, the incubation period can be as long as three weeks.
“This is a very aggressive virus that destroys the immune response and multiple organs,” Health Minister Dr Sabin Nsanzimana said. “It is the second if not the first most deadly virus ever known.”
“The good news is some patients are improving, five patients have tested negative already and we are awaiting a second round of testing to make sure they are clear of the virus,” Dr Nsanzimana added.
Ring vaccination
Currently, there are no approved rapid tests, treatments or vaccines to combat Marburg virus. The latest epidemic is therefore a rare opportunity to test candidates currently in development.
The last outbreak, which took place in Equatorial Guinea in 2023, ended before any novel medical tools were tested. Then, there were 12 deaths and 17 survivors among people who tested positive for the virus, as well as 23 other suspected fatalities.
After that outbreak, broad stroke plans for a vaccine trial were drawn up, and a WHO advisory board has suggested that a candidate developed by the Sabin Vaccine Institute in Washington DC should be prioritised for trial in any new outbreak.
The vaccine platform uses a modified chimpanzee adenovirus, and a previous trial in 40 healthy volunteers in the United States found it was safe and generated an immune response.
A larger trial in Uganda and Kenya is currently underway, but these studies cannot prove if the shot is effective against Marburg.
“You can’t test the vaccine unless you have the disease, so when there is an outbreak that’s when you can see if it works,” said Dr Krutika Kuppalli, a spokesperson for the Infectious Disease Society of America and former WHO medical officer.
“I would assume healthcare workers will be vaccinated and it will be used in a ring vaccination, contacts of cases, and contacts of contacts,” Dr Kuppalli added.
Trial acceleration
Ring vaccination has been successfully used in West Africa and the Democratic Republic of the Congo to curb past Ebola outbreaks. The method creates a protective “ring” around those at risk of infection. When a case is identified, officials trace the infected person and prioritise vaccination for their immediate contacts—like family members, coworkers, and healthcare workers who have treated them.
On September 30, a strategy for this was further discussed in a virtual meeting featuring the WHO, Rwandan scientists, the Coalition for Epidemic Preparedness Innovations, and members of the Marburg virus vaccine consortium on September 30.
Though reluctant to announce concrete plans publicly, the Rwandan Health Ministry said on Thursday that it is working to accelerate trials.
“In terms of therapeutics and vaccines, protocol has been finalised and submitted and our national review and ethical boards have provided approval so we should get these products in terms of days,” Dr Nsanzimana, the health minister, said on Thursday.
“We should have an update next week in terms of where we are at,” he added.
But although it is the furthest along in trials, Sabin’s shot is not the only Marburg vaccine candidate in development. The International Aids Vaccine Initiative in New York is set to start production of its shot – which is similar to an approved Ebola vaccine – this week, while the University of Oxford launched a phase one trial in July.
‘We need more to stop this outbreak’
This vaccine uses a similar viral technology as the Sabin candidate, according to Prof Teresa Lambe, a vaccinologist leading Oxford’s Marburg vaccine’s development.
“The rollout of vaccines along with testing of therapeutics and other interventions is incredibly important during an outbreak,” she told the Telegraph, adding that the early UK study will test the safety and immune response.
The Oxford candidate went into phase one clinical trials in July, the first UK-based study of a Marburg shot. The researchers are currently testing the safety and immune response of the vaccine in a group of the shot in 46 healthy adults aged between 18 and 55.
There are also plans to use other tools.
Gilead Sciences, an American pharmaceutical company that develops antivirals for the treatment of diseases like HIV/Aids, influenza, and Covid-19, said on Thursday it would donate 5,000 vials of the drug Remedesivr to Rwanda for use against Marburg.
The drug is not approved for treatment against the disease and its safety and efficacy against the virus is unknown, Gilead said.
Amid all this, Rwandan health authorities are working on community awareness to make sure anyone with symptoms knows to seek care urgently.
It is easy to confuse early symptoms of Marburg with other diseases like Covid-19 and mpox, Dr Nsanzimana said, and co-infections are common.
“We will do everything that is possible, we are doing our best, but Africa CDC, Rwanda, and all partners will need more to stop this outbreak,” Dr Jean Kaseya, Director-General of Africa Centres for Disease Control and Prevention said.
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