Ebola vaccine halves the chance of dying from the disease, says new study

Whenever Miriam Alia, head of vaccines and outbreak response at Doctors Without Borders, went to visit an Ebola patient in their community, she only had a notebook to write down the names of the people who had been in contact with them and very little hope. “I knew that a lot of people were going to die. Sometimes, it was up to 90% of those who became infected.”

That was until 2015, when in the middle of the epidemic in Guinea, Sierra Leone, and Liberia — the worst in history with 11,300 dead and 28,000 infected — an effective vaccine was developed against several of the six species of the virus.

“Now,” says Alia, “you arrive at the place where an outbreak has occurred and you have something which prevents transmission and protects the community. You give families hope.” A study carried out by Epicenter, the NGO’s medical research and epidemiology center, whose results have been published by The Lancet, shows that the rVSVΔG-ZEBOV-GP injection — the single-dose vaccine recommended by the WHO in the event of an epidemic — not only reduces the risk of infection, but also reduces mortality among patients by half.

The researchers analyzed the cases of 2,279 confirmed Ebola patients between July 2018 and April 2020 in the Democratic Republic of the Congo (DRC). According to their findings, 56% of unvaccinated patients died, compared to 25% of those who had received the Ervebo injection, the commercial name of the vaccine.

“It is important because we now know that if a person is already incubating the virus when they receive the vaccine, they are still more likely to survive,” Etienne Gignoux, director of the Department of Epidemiology and Training at Epicenter, stresses in a phone interview. “These are lives saved. Ebola leaves many children orphaned, families destroyed, and health systems in tatters,” adds Alia, who has intervened in most of the outbreaks declared in the DRC, “before there was a vaccine and after.”

Jean-Pierre Kaposo, a doctor at the hospital in Goma knows this well. The health center in which the research was carried out is in the capital of the province of North Kivu. It is one of the epicenters where that great epidemic of 2018–2020 occurred. “We faced insurmountable challenges. The fear was pervasive. At first, the residents of Beni did not want to accept that Ebola was real,” he says about those dark days. “They believed it was staged by the government to secure international financing.” Despite these difficulties, the doctor and his team worked tirelessly to save lives and contain the spread of the virus. “Every day was a struggle, but we found strength in our commitment to our patients and our community,” he adds.

Now you arrive at the community where an outbreak has occurred and you have something which prevents transmission and protects people. You give families hope

Miriam Alia, MSF

According to data from the Center for Disease Prevention and Control, until June 25, 2020, when the WHO declared the end of the worst Ebola epidemic that the DRC has ever suffered, 3,470 cases had been reported, of which 2,287 (66%) were deaths. Marie, a mother from Goma who does not want to give her full name, was one of the survivors. “When I realized I had Ebola, I feared for my life and the lives of my children. But thanks to the doctors’ care and my own determination, I beat the disease,” she says.

The Ebola virus is named after the river in the DRC next to which an outbreak occurred in 1976. That was the outbreak in which Belgian microbiologist Pier Pior discovered the infectious agent that had killed 400. Since then, 15 outbreaks have been recorded in the country. The last was at the end of August 2022, when a case was detected in Beni, in the troubled province of North Kivu. The sole patient in that outbreak died, but no further infections occurred and the Congolese government declared the end of the crisis just a month later.

Today it is known that the incubation period of the worm-shaped virus that wriggled under Pior’s microscope is between two and 21 days. It is of animal origin, but it also spreads among humans through direct contact with the blood or bodily fluids of infected people, and it is extremely deadly. On average, it kills half of infected patients, although it has been known to wipe out up to 90% of those it infects.

The most common thing is that the early symptoms — tiredness and headaches, aching muscles and joints — usually appear a week after being infected. Their extreme similarity to the symptoms of malaria and other common ailments, makes early diagnosis difficult when a first case occurs in a community. Moreover, infections almost always take place in rural areas. This causes front-line health personnel and the people close to the patient to also become infected.

“Pain behind the eyes and hiccups are very typical symptoms of Ebola, and they indicate that it will be especially aggressive,” says Alia. But the alerts that it may be this disease are not usually sounded until a few days after the patient’s fever rises, and vomiting, diarrhea, and internal and external bleeding occur. With antiretroviral treatment, rehydration therapy, and blood transfusions, among other interventions, patient survival has been increased. It is now known that if they are also vaccinated, even if they have already been exposed to the virus, it will further contribute to reducing the chances of dying.

The Ebola virus is extremely deadly. On average, it kills half of infected patients

Research also shows that the sooner those who have been exposed to the virus are vaccinated, the higher the likelihood of them surviving. Of the patients who were immunized at least 10 days before the appearance of the first symptoms, 17% died. Of those who were vaccinated between three and nine days before developing the disease, 20.1% died. Finally, 27.3% of deaths were recorded among those who received the injection just two days before presenting fever and pain. “When an outbreak is declared, we recommend vaccinating front-line health professionals and the ring vaccination of contacts of positive cases. Now we also add that it must be done as soon as possible,” Gignoux notes.

“As there is very little production of the vaccine and it is expensive — each dose costs about $107 — so the vaccine is only used when there is an outbreak. However, it was used preventively among health professionals for the first time in 2023. Now we also know that it has therapeutic value,” explains Alia. “This means that we are certain that we can vaccinate contacts and, although they are already incubating the virus, the injection will not make them worse. In fact, it will contribute to reducing mortality.”

The researchers have also verified that the administration of Ervebo is compatible with the medication prescribed to Ebola patients. “This opens the door to post-exposure vaccination of people with symptoms, which was not done until now,” the MSF specialist says. “Now, an unvaccinated person who is admitted with Ebola can be administered the vaccine at the same time as the treatment,” she explains.

Stop transmission, avoid stigma

A single confirmed case of Ebola is an outbreak. Normally, the patient has already deceased. It might be that a nurse sees unexplained deaths in their community or entire families fall ill after a funeral. Similarly, it might be the professional themself who becomes infected after caring for patients with Ebola-like symptoms. In these cases, the health worker communicates their suspicions as best they can, by telephone or by sending a message by bicycle. This alerts an investigation team that travels to the affected area. “In the outbreak in Congo in 2014, the nurse began to treat the sick with garbage bags on his hands as the only protection while he sent someone to ask for help. “And he didn’t get infected!” Alia recalls with surprise, since the Ebola virus is extremely contagious.

When the diagnosis of patient zero is confirmed, a single treatment center is established to which all suspected and confirmed cases are referred. First it is usually the local dispensary, which ceases all other activity, and, only when a specific health complex has been built, is the previous one disinfected and it regains its function. Positive cases are isolated and treated. Within this clinic, specialists care for patients in teams of two: one works directly on the patient, and the other helps them put on and take off the protective suit (PPE) and ensures that they do not make mistakes that put their own safety at risk.

Outside, the investigation team draws up a list of contacts (including front-line healthcare workers), quickly isolates suspected cases, carries out rapid testing — the results of which are obtained in two hours — and now also vaccinates those who want it.

The containment and treatment of hemorrhagic fevers is a scheduled process that the affected countries and the professionals from the organizations that support them know very well. Ebola almost always manifests itself in small outbreaks in rural areas with a widely dispersed population. These outbreaks can be quickly extinguished with this early isolation strategy, helped by the lack of contact between neighbors, and now vaccination to stop transmission.

People were afraid of me even after I was cured. But I refuse to let my illness define me

Pierre, superviviente del ébola en DRC

So what happened in the 2014 epidemic, which lasted two years and affected thousands in three countries? “The outbreak began in March 2014 in a rural area that was a border intersection point where there is a lot of population movement,” explains Alia. Once the virus reached the capitals and large hospitals, it spread like wildfire. “The WHO response was massively delayed, and didn’t occur until August. They said we were exaggerating when we said we couldn’t cope,” she recalls. By then there were already 500 new infections per week between Guinea, Sierra Leone, and Liberia. “And there was a lack of coordination between the countries that made contact tracing difficult,” says the MSF specialist.

The stigma associated with Ebola is very strong, which is why it is so important to stop transmission and prevent the spread of infections thanks to the vaccine. For Pierre, a young man from Beni, the social stigma that followed his recovery from Ebola posed an additional challenge. “People were afraid of me, even after I was cured,” he says in a telephone conversation. “But I refuse to let my illness define me. “I am a survivor and I am proud of it.”

Alia remembers Salomé, a Liberian nurse who survived the 2014 epidemic and who featured on the cover of Time magazine. She died in 2017, at only 29 years old, after suffering complications after giving birth to her fourth child, as she was not treated in the hospital when health workers found out that she had been sick with Ebola. “Any scientific advance in disease prevention not only prevents people from dying, but also prevents them from getting sick in the first place,” the expert concludes.

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