Marburg disease outbreak: Why has no vaccine been approved for a deadly disease like Ebola?

Marburg disease epidemic. It is closely related to Ebola hemorrhagic fever and can cause severe symptoms. deadly The disease is spread In Rwanda. While Africa is facing difficulties, exacerbating public health challengeswhich brings a rare sign of hope. It's a chance to test new vaccines that could potentially save lives across the continent in the future.

The World Health Organization (WHO) announced in a press conference on Thursday that the country's first patient infected with the virus died on September 8th. As of September 29, a total of 36 infections and 11 deaths have been reported, making it one of the most dangerous countries. maximum Historical Marburg craze. Most of the infections are among healthcare workers at two hospitals in the East African capital, Kigali, but cases have been reported in seven of Rwanda's 30 districts. it is beginning Since the virus became known to cause infections in Rwanda.

WHO shown This outbreak is likely to spread to neighboring countries, but the risk of further global spread is low. Humans usually become infected when they come into contact with Egyptians who carry Marburg disease. fruit bata species found in parts of Africa, the Middle East, and western Asia. However, once a person is infected with the virus, they can spread it to others through bodily fluids or contact with contaminated surfaces or materials (such as clothing or bedding). This mode of transmission means that Marburg virus does not spread as easily as, for example, COVID-19 or other respiratory diseases.

However, as we have seen, previous Due to the Marburg virus outbreak, travelers returning from countries with outbreaks can bring the disease to their home country. already, 1 person The man who came into contact with the infected person in Rwanda had traveled to Belgium, highlighting the possibility of isolated cases occurring overseas.

Historically, Marburg virus disease becomes fatal in about 10 years. 50 percent However, in past outbreaks, mortality rates have exceeded 80%. people experience High fever, severe headache, extreme fatigue, rashbloody diarrhea, abdominal pain, and Bruises of unknown cause Bleeding from the nose and gums. Symptoms can appear anywhere 2nd to 21st After the first infection.

all previous Marburg virus outbreaks have occurred in sub-Saharan Africa, most recently in Tanzania. eight Five cases of infection and five deaths were confirmed, and a case of infection was also confirmed in Equatorial Guinea. 16 confirmed cases And 12 people died. Both outbreaks occurred in 2023. From 1967 to 2008, Marburg disease was reported in the United States, Germany, Yugoslavia, and the Netherlands among travelers returning from Uganda.

To date, there are no approved treatments or vaccines for Marburg virus disease, but at least treatments and vaccines exist. 4 Vaccine under development. All four of us were like that. effective In research involving animals. small early stage clinical trial Promising results were obtained in humans. However, study participants who received the Marburg vaccine were not exposed to the virus to test how well the vaccine protected. 2 more vaccine This is because Ebola virus may also be effective against Marburg virus.

Rwandan researchers are preparing to submit a phase 3 trial protocol to Rwanda's Ethics Committee for approval. This will be an opportunity to accelerate the development of vaccines and treatments for Marburg virus and conduct large-scale trials in real-world outbreaks.

If trials move quickly, the current crisis could lead to scientists identifying a vaccine that will protect millions of people in the coming years.

WHO, Rwanda Public Health Authority, and group of scientists and institutes working on vaccine research met They will meet earlier this week to discuss quickly starting vaccine trials that could help quell the ongoing outbreak.

Of the vaccine candidates in development, the one most likely to be tested if trials proceed in Rwanda is the cAd3-Marburg vaccine developed by the National Research and Development Agency. research institute National Institute of Allergy and Infectious Diseases (NIAID). Last year, NIAID tested the vaccine's safety in humans for the first time in a Phase 1 clinical trial. trial.

Forty healthy adults were given one of two different doses of the vaccine, and side effects were observed and whether their immune systems produced antibodies. This indicates that the vaccine is effective if the individual is exposed to the virus. The vaccine was deemed safe, with 95% of participants developing antibodies four weeks after vaccination. However, because the participants had not been exposed to the virus, the vaccine's actual effectiveness could not be assessed.

Early this year, Sabin Vaccine Institute started Phase 2 clinical trial for NIAID vaccines in Uganda and Kenya; Healthy adults will be randomly assigned to receive either the vaccine or a placebo and then monitored again for adverse reactions and antibody responses. Additionally, participants will not be infected with Marburg virus during this trial.

Typically, if Phase 2 trials are successful, scientists move on to large-scale Phase 3 trials, where they roll out the vaccine to large groups of people and observe the effects when individuals are exposed to the virus. The emergency situation in Rwanda could accelerate this process. Even if Phase 2 results are not yet available, scientists may proceed with Phase 3 trials.

Researchers and health officials have been preparing for this. Earlier this year, WHO and scientists from 17 countries at risk of Marburg virus outbreaks protocol To test both vaccine Treatment during an epidemic. The phase 3 clinical trial in Rwanda will follow a ring vaccination strategy in which contacts of infected people are vaccinated. There are two groups in the trial: a group of contacts who will be vaccinated immediately, and a “delayed” group who will probably be vaccinated later. Researchers will then compare the effects of the vaccine between the two groups.

Scientists may also test treatments that use antibodies, proteins made by the immune system, against viruses to kill viruses and other pathogens. one study They found that treating animals such as guinea pigs and monkeys with these antibodies after being infected with Marburg virus could prevent severe illness and death. Medical workers successfully treat patients using antibodies cocktail Also during the previous Ebola virus outbreak.

The WHO's ethics committee has already approved trial protocols for vaccines and antibody treatments, a spokesperson told Vox. The next step is for these protocols to be approved by Rwanda's national ethics committee. Two Rwandan researchers have been selected to lead these efforts in the country.

One more hurdle remains. is less than 2,000 Total vaccine doses currently available. As of April 2023, the Sabin Vaccine Institute had produced about 850 of those doses. Oxford University is developing another Marburg vaccine and has around 1,000 doses available. Larger scale production may be needed, especially if the infection spreads further. The Sabin Vaccine Institute and the University of Oxford both have existing manufacturing capacity for the Marburg vaccine and have previously informed the WHO that additional doses can be produced quickly.

The Marburg disease outbreak comes amid a surge in mpox outbreaks in the region, leading to the World Health Organization declared Global Health Emergency in August. The Democratic Republic of the Congo, which borders Rwanda, epicenter About the Npox craze. (The Democratic Republic of the Congo has not yet recorded the Marburg incident.)

Fortunately, Rwanda strongest Africa has poorly developed public health systems and only a handful of mpox cases have been reported. Estimation 90 percent The majority of the population has health insurance, which is much more expensive than most of its neighboring countries. Rwanda also has strong infectious disease surveillance system and history success in containing the outbreak;

This makes it an ideal environment to test the Marburg vaccine during the current outbreak, if public health authorities can act quickly. The race is on.