An outbreak in Marburg, a virus closely related to Ebola that can be deadly and often fatal deadly disease, is spreading out As Africa grapples with complex public health challenges, Rwanda presents a rare silver lining: an opportunity to test new vaccines that could save lives across the continent in the future.
The first patient infected with the virus in the country died on September 8, the World Health Organization (WHO) said at a press conference on Thursday. As of September 29, a total of 36 cases and 11 deaths have been reported, making it one of the highest the largest Marburg outbreak in history. While most of the infections are among health care workers at two hospitals in the East African country of Kigali, cases have been reported in seven of Rwanda’s 30 districts. it is the first The virus is known to cause infection in Rwanda.
WHO indicated The outbreak is more likely to spread to neighboring countries, but the risk of further global spread is low. Usually, people become infected when they come into contact with Egyptians carrying Marburg fruit batA species found throughout Africa, the Middle East and parts of western Asia. Once a person has contracted the virus, it can spread to others through contact with bodily fluids or contaminated surfaces and materials such as clothing or bedding. This mode of transmission means that the Marburg virus will not spread as easily as Covid-19 or other respiratory diseases.
This story first appeared in the Future Perfect Newsletter.
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However, as we have seen previous In Marburg virus outbreaks, travelers returning from countries experiencing outbreaks can introduce the disease into their home countries. already, a person Those who came into contact with an infected patient in Rwanda traveled to Belgium, raising the possibility of isolated foreign cases.
Historically, Marburg virus disease is almost fatal 50 percent patients, but in some previous outbreaks, the mortality rate exceeded 80 percent. people experience High fever, severe headache, extreme fatigue, the rashBloody diarrhea, flatulence, and Unexplained wound and bleeding from the nose and gums. Symptoms can appear from anywhere 2 to 21 days After initial infection.
all previous Outbreaks of Marburg virus have occurred in sub-Saharan Africa, most recently in Tanzania, where there were eight Confirmed cases and five deaths, and in Equatorial Guinea, where there were 16 confirmed cases and 12 deaths; Both outbreaks occurred in 2023. Between 1967 and 2008, the United States, Germany, Yugoslavia, and the Netherlands reported cases of Marburg disease in travelers returning from Uganda.
To date, there is no approved treatment or vaccine for Marburg virus disease, but at least there is four Vaccines in development. All four have happened effective In studies involving animals. A small, early-stage clinical trial There were promising results in humans; However, study participants receiving the Marburg vaccine were not exposed to the virus to test how protective the shot was. The other two vaccination For Ebola virus may also be effective against Marburg virus.
The Rwandan researchers are preparing to submit the protocol for the phase 3 trial to the Rwandan Ethics Committee for approval. This will be an opportunity to accelerate the development of vaccines and treatments for Marburg virus and to conduct larger trials in a real-world outbreak.
If the trial moves quickly, the current crisis could allow scientists to identify a shot that will protect millions of people for years to come.
Thin vaccination is the silver lining
WHO, Rwanda Public Health Officer and A group of scientists and institutions Vaccine research work see earlier this week to discuss quickly setting up a vaccine trial that could help contain the ongoing outbreak.
Among the vaccine candidates, the most promising that appears to be tested in Rwanda when the trial goes ahead is the cAd3-Marburg vaccine developed by National Institute Allergy and Infectious Diseases (NIAID). Last year, the NIAID conducted the first phase 1 clinical trials of the vaccine for human safety trial.
Forty healthy adults received two different doses of the vaccine and were monitored for adverse reactions and to see if their immune systems produced antibodies, an indication that the vaccine would be effective if the individuals were exposed to the virus. The vaccine was considered safe, and 95 percent of participants developed antibodies four weeks after receiving it. However, the participants were never exposed to the virus, so the practical effectiveness of the vaccine was not evaluated.
Earlier this year, The Sabin Vaccine Institute Start a Phase 2 Clinical trial For NIAID vaccines in Uganda and Kenya. Healthy adults will be randomly assigned to receive the vaccine or a placebo shot and then be monitored again for adverse reactions and antibody responses. Participants will also not be exposed to the Marburg virus during this trial.
Typically, if a Phase 2 trial is successful, scientists move on to a larger Phase 3 trial and roll out the vaccine to a larger group and then monitor its effects when individuals are exposed to the virus. The Rwandan emergency may accelerate this process. Scientists can move forward with Phase 3 trials even though Phase 2 results are not yet available.
Researchers and health officials are preparing for this. Earlier this year, the WHO and scientists from 17 countries at risk of Marburg virus outbreaks developed protocol To test both vaccination and treatment during an outbreak. A phase 3 clinical trial in Rwanda will follow a ring vaccination strategy in which contacts of infected individuals are vaccinated. The trial will consist of two groups, a group of contacts who are vaccinated immediately and then a second “delayed” group who are possibly vaccinated at a later time. Researchers will then compare the effects of the vaccine between the two groups.
Scientists may also test a treatment that uses antibodies, proteins made by the immune system, to fight viruses and other pathogens. one Study It has been shown that treatment of animals such as guinea pigs and monkeys after infection with Marburg virus prevents severe illness and death. Medical staff have successfully treated patients with antibodies cocktail During previous Ebola virus outbreaks.
The WHO’s ethics committee has already approved the protocol for the vaccine and antibody treatment, a spokesperson told Vox. The next step is to have these protocols approved by an ethics committee within Rwanda. Two Rwandan researchers have been selected to lead this effort in the country.
One more hurdle remains. There is less than that 2,000 Total vaccine doses currently available. As of April 2023, the Sabin Vaccine Institute had produced approximately 850 of these doses. Oxford University, which is developing another Marburg vaccine, had about 1,000 doses. Large-scale production may be necessary, especially if the outbreak is more widespread. Both the Sabin Vaccine Institute and the University of Oxford have existing manufacturing capacity for the Marburg vaccine and previously reported to WHO that they could rapidly produce additional doses.
The Marburg outbreak ignited a growing mpox outbreak in the region, which the World Health Organization announced August is an international health emergency. Democratic Republic of the Congo, which neighbors Rwanda epicentre mpox outbreak. (The DRC has not yet recorded any cases in Marburg.)
Fortunately, Rwanda has one strong African public health systems and have reported only a few empox cases. an approximation 90 percent The population has health insurance, much more than its neighbors. Rwanda also has a robust communicable disease surveillance system system and a history Successfully contain the outbreak.
This makes Marburg an ideal setting for testing a vaccine during the current outbreak – if public health authorities can move quickly. The race is on.
