After more than two decades of research, the world finally has an approved Ebola vaccine.

The European Commission granted marketing authorization to Merck’s vaccine, known as Ervebo, on Monday, less than a month after the European Medicines Agency recommended it be licensed. It is currently being used in the Democratic Republic of the Congo under a “compassionate use” or research protocol similar to a clinical trial.

“The European Commission’s marketing authorization of Ervebo is the result of an unprecedented collaboration for which the entire world should be proud,” Ken Frazier, Merck’s chairman and chief executive officer, said in a statement.

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“It is a historic milestone and a testament to the power of science, innovation and public-private partnership,” Frazier said, adding the company will work with the Food and Drug Administration in the United States and regulatory agencies in a number of African countries to license the vaccine.

Frazier said Merck will also work with the World Health Organization on vaccine prequalification, a process in which the global health agency assesses vaccines and other medical processes in order to assure member countries that they are safe and effective. Developing countries often use WHO prequalification as guidance when they make their own decisions about whether to license a product.

WHO Director-General Tedros Adhanom Ghebreyesus said prequalification of the vaccine will now take place quickly. “This can be done in the next few days,” he said via email.

“This is great news that will change Ebola prevention in the future and protect the vulnerable,” Tedros, as he is known, said about the European approval.

The European Commission said licensing a vaccine has been a priority since the devastating outbreak in West Africa in 2014-2016, when more than 28,000 people were infected and over 11,000 died. It remains the largest Ebola outbreak in known history.

While the FDA has until March 2020 to issue a decision, a representative said recently that it expects to issue a ruling “well ahead of” the March action date.

The vaccine, which protects against the Zaire species of Ebola, was designed at Canada’s National Microbiology Laboratory with funding from the U.S. government’s Biomedical Advanced Research and Development Authority. Dr. Heinz Feldmann led the research. He now heads the National Institute of Allergy and Infectious Diseases’ virology laboratory in Hamilton, Mont.

For years Feldmann worried neither this nor any other Ebola vaccine would be made, because there isn’t a traditional market for such a product. Outbreaks are sporadic and typically occur in countries that cannot afford to pay the prices that might be attached to a vaccine that is sold in limited numbers of doses.

“I think it’s a good day,” he told STAT on Monday after learning the vaccine had finally been licensed.

The scientist whose work forms the structure on which the vaccine was built was also delighted by the news.

John “Jack” Rose, a research scientist at Yale University, developed what is effectively a delivery system to safely expose the immune system to pathogens for the purpose of vaccination. Rose and colleagues in his lab genetically modified a vesicular stomatitis virus (VSV) that infects livestock but that doesn’t cause illness in people. Feldmann’s team at the Canadian lab fused a key Ebola protein to that VSV backbone to make the vaccine that has come to be known as Ervebo.

“It is thrilling to see the first licensing of a VSV-based vaccine vector system for use in humans where it has already saved many lives!” Rose told STAT. “Numerous scientists worked for many years in my laboratory at Yale to develop this potent vaccine platform.”

While the vaccine has come to be known as Merck’s Ebola vaccine, in reality scores of researchers and Ebola outbreak response workers in Canada, the U.S., Europe, and Africa played a role in paving Ervebo’s path to licensure, whether that was in designing it, conducting pivotal pre-clinical studies in animals, or the clinical trials Merck used to support its application.

Tedros lauded the work of the teams of vaccinators who have been using Ervebo in the outbreak in the DRC, where more than 250,000 people have been vaccinated. Because the vaccine hasn’t been licensed yet in DRC, it will continue to be used there under the compassionate use protocol, which is more time consuming than administration of a fully licensed vaccine.

Merck has been donating the vaccine that is being used and will continue to do so for some time to come. Beth-Ann Coller, the team leader on the Ebola vaccine, said all existing stock of the vaccine is investigational — it was made before the vaccine was licensed. The company will continue to donate that vaccine.

Merck expects that licensed doses made at the company’s production facility in Burgwedel, Germany, will become available during the third quarter of 2020. Merck said it has not yet set a price for Ervebo, but has made a commitment to make the vaccine available to countries eligible for purchasing assistance through Gavi, the Vaccine Alliance, at the lowest price possible.

The vaccine was proved to be protective during the West African outbreak. But for that rare opportunity to test the vaccine, and for the concerns it raised about Ebola’s power to spread, Ervebo might still be a good idea gathering dust.

The vaccine was originally licensed to NewLink Genetics (NLNK), a small biotech company, which did little to advance it.

During the late summer and fall of 2014, when spread in Guinea, Sierra Leone, and Liberia was reaching crisis proportions, Merck entered into discussions to take over the product. A clinical trial conducted in Guinea near the end of the outbreak confirmed that the vaccine was highly protective.

“That big outbreak was a game-changer and reminded people that this exotic virus could become a real threat to public health regionally as well as in a global perspective,” Feldmann said.

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  • not to bust anyone’s chops
    but biologically speaking, the high mortality rates of Ebola virus is an indication of a parasite not yet well adapted to its host, that is, it hasn’t yet developed sophisticated mechanisms to evade the host immune system. Consequently, and luckily, it is a rather easy target for making a successful vaccine against it.

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