Ebola Outbreak in the DRC: Current Situation and Response Efforts

The recent Ebola outbreak in the Democratic Republic of Congo has caught global attention, and it’s now marked as the third-largest recorded outbreak. It’s worth noting that this is the 17th outbreak the DRC has faced since the virus was first identified back in 1976.

Ebola can be deadly, with fatality rates ranging from 25% to as high as 90% in infected individuals. Currently, scientists are in a race to develop potential vaccines and treatments to combat this outbreak, but authorities have made it clear that none have been approved just yet. The question is, why is that?

This particular outbreak stems from the Bundibugyo strain of the virus, previously linked to two earlier outbreaks—one in 2012 that resulted in 38 confirmed cases and 13 deaths, and another in 2007 along the DRC-Uganda border, which saw 131 cases and 42 deaths.

Infections are most often associated with the Zaire strain, which has caused the largest outbreaks in history. The outbreak from 2014 to 2016 in West Africa was particularly devastating, followed by another significant outbreak in the DRC from 2018 to 2020. Combined, these outbreaks claimed over 11,000 and more than 3,000 lives, respectively.

During the West Africa outbreak, a vaccine named Ervebo was successfully developed and tested in 2015, later receiving FDA approval in 2019. It’s been authorized in various countries across Europe and Africa.

However, the development efforts haven’t quite extended to cover other strains like Bundibugyo.

Dr. Anne Ancia, a representative for the World Health Organization in the DRC, mentioned that the idea of utilizing existing vaccines has been considered. But, there’s not enough data to clearly establish how well a Zaire-targeted vaccine would protect against Bundibugyo, and safety remains a significant concern.

“I wouldn’t want to be the doctor making that call,” shared Dr. Thomas Geisbert from the University of Texas Medical Branch, who researches Ebola interventions. He noted that while a similar vaccine to Ervebo showed success in protecting monkeys against Bundibugyo, the initial study involved only four animals due to ethical and financial constraints.

In this small test, three out of four monkeys were protected after receiving the Zaire-targeted vaccine and then being exposed to Bundibugyo 28 days later. “That’s promising,” Geisbert commented. Yet, models indicate Bundibugyo might be less lethal than Zaire, suggesting that perhaps 50% protection is feasible, though more extensive research is necessary.

There’s also a pressing question of safety: administering a vaccine designed for a different strain could potentially interfere with a person’s immune response if they’ve already been exposed to Bundibugyo. “You don’t want to make things worse,” he advised.

Dr. Sylvie Briand, WHO’s chief scientist, expressed concerns as well, stating there’s minimal evidence indicating cross-protection for Bundibugyo, thus Ervebo isn’t regarded as a primary vaccine candidate presently.

On the production front, Merck, the makers of Ervebo, has distributed over 500,000 doses to a global Ebola vaccine stockpile over the last five years. The company also mentioned that it could ramp up manufacturing if the decision is made to deploy Ervebo in this ongoing outbreak.

The experiences with the Covid-19 pandemic and the 2014 Ebola crisis demonstrate that vaccines can be developed more quickly during emergencies. Currently, there’s ongoing work in that direction.

A promising avenue seems to be an experimental vaccine, similar to Ervebo but specifically aimed at Bundibugyo. Dr. Vasee Moorthy, a senior WHO adviser, elaborated on this approach, which utilizes a different virus to train the immune system to recognize an Ebola protein.

Encouragingly, Geisbert noted that this vaccine has provided complete protection in nonhuman primates and has potential as a post-exposure treatment, akin to rabies vaccines. However, clinical-grade materials for human testing aren’t available yet and may take around six to nine months to prepare.

This particular vaccine deserves high priority, according to Moorthy. Additionally, the nonprofit biomedical group IAVI is focusing on an investigational Bundibugyo vaccine, having utilized similar technology for other viruses.

Merck is also in discussions about potential collaborations with global health organizations for both research and vaccine development as they explore their support options.

Another candidate vaccine is being developed with technology similar to the one used in the Oxford/AstraZeneca Covid-19 vaccine. While it could be rapidly produced, it has less supporting data. Nonetheless, in life-or-death situations like Ebola, the risks could be justified.

Oxford stated that its Covid-19 vaccine was credited with saving millions of lives in 2021 alone.

This vaccine would employ an adenovirus to deliver genetic material that helps train the immune system to identify the Ebola virus protein. Doses could potentially enter human trials within a couple of months through collaboration with the Serum Institute of India.

As manufacturing is underway, the availability of animal data will dictate whether this becomes a viable candidate for Bundibugyo.

There’s a sense of optimism regarding therapeutics as well. Moorthy mentioned the possibility of starting trials soon with some existing drugs that may be effective against Bundibugyo.

Broad-spectrum strategies are on the table too, especially since the options for directly targeting Bundibugyo are scant. Antiviral medicines like remdesivir, used for Covid-19, and a monoclonal antibody cocktail called MBP134 are being considered. However, logistical hurdles may come into play, given the challenging operational context in Ituri province, where the outbreak is currently centered.

Geisbert highlighted that MBP134 currently boasts promising preclinical data, showing effectiveness in protecting monkeys even at advanced illness stages, spanning various Ebola strains.

There’s also Regeneron’s approved antibody cocktail Inmazeb, which contains components effective against Bundibugyo, albeit not yet tested in clinical settings.

WHO scientists have indicated that both Regeneron’s cocktail and MBP134 will be prioritized for clinical trials. An oral antiviral, obeldesivir, is also under consideration for post-exposure prevention in high-risk individuals, which could simplify administration considerably.

“This could potentially prevent the disease from developing in contacts exposed to the virus,” noted WHO’s Briand.

Is the US Government Supporting Drug and Vaccine Development?

Historically, the U.S. has played a significant role in funding trials during health crises, although support for global aid programs has seen declines recently. The Biomedical Advanced Research and Development Authority (BARDA) backed the development of Ervebo and related antibody therapies.

In 2018, Mapp Pharmaceuticals received substantial funding to initiate human clinical trials for MBP134 after prior animal studies indicated its effectiveness against Ebola.

Almost immediately, BARDA facilitated the shipment of experimental antibody treatments for possible use among high-risk individuals in the U.S. But there hasn’t been a clear response regarding potential support for trial efforts in the DRC for vaccines targeting Bundibugyo.

Mapp, while unable to comment on supply questions, stated that they have sufficient quantities for trials and that the drugs are managed by BARDA.

Regeneron has previously offered its FDA-approved treatment at no cost in outbreak regions. They’ve also contributed to the government stockpile, setting plans to provide their antibody with Bundibugyo action in response to the current outbreak.

“We’re enhancing production of the single antibody, maftovimab, in case further treatment is needed,” Yancopoulos mentioned.

Rojek pointed out a troubling pattern: funding for Ebola research often swings drastically between panic during outbreaks and neglect in quieter times, leading to frustration in countries constantly dealing with Ebola.

“If this outbreak occurred in Europe or the U.S., I assure you that vaccines and treatments would be readily available,” voiced Dr. Jean Kaseya, who heads Africa’s Centers for Disease Control and Prevention. “We must push forward with research and development.”

Reflecting on the 2014 Ebola outbreak, Geisbert noted a similar sense of urgency: “Everyone was scrambling back then too,” emphasizing the progress that’s been made but acknowledging the challenges that remain.

Despite the hurdles, Rojek believes there’s been progress since a decade ago: robust surveillance systems, quicker diagnostics, and better international coordination are vital improvements. However, the current outbreak’s complexity requires more than just vaccines—effective strategies such as rapid diagnosis, isolation, and community trust are also essential.

“Vaccines and therapeutics are invaluable, but they’re not the sole solutions to controlling outbreaks,” she concluded.