The new suspected cases of the disease follow the reports of 45 others and 25 deaths across the country since April 4. Fourteen of those cases were confirmed as Ebola, according to the global health organization, which now assesses the risk of much wider spread in the region to be “very high,” the agency’s second-highest threat level.

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The WHO now says nine countries neighboring Congo are “at high risk of spread.”

In what could be a milestone of progress—and I emphasize “could be”—the threat of outbreak will be met this time with a new weapon, a vaccine that has been demonstrated in at least some human trials to have “high protective efficacy and effectiveness to prevent Ebola virus disease.” The Merck vaccine rVSV-ZEBOV, developed at the Public Health Agency of Canada’s National Microbiology Laboratory, was tested in several thousand people who were either contacts or “contacts of contacts” of individuals with confirmed Ebola virus disease after a 2015-16 outbreak in Guinea, West Africa. None of those vaccinated developed the disease after 10 days, even as 16 people in the unvaccinated comparator group did, according to a report in the Lancet. It remains unclear how long that apparent protective effect will last, though evidence suggests than antibodies to the disease in vaccinated individuals can last two years or more.

At least a few researchers have suggested that there should be a question mark on this recent study, despite the large number of people tested. But public health officials are moving forward with what they call a “ring vaccination.” The WHO tweeted out on Wednesday that “A first batch of 4000 #Ebola vaccine doses” had just arrived in Kinshasa, the Congo’s capital city.

We will see soon enough if we’ve reached a turning point in one of the greatest public health challenges around.