Three years ago, 49 people died of Ebola in the Democratic Republic of Congo—and in the unrelated outbreak that devastated West Africa between 2014 and 2016, over 11,000 deaths were recorded. So it’s no wonder that news of Ebola’s return to Congo set off alarm bells for health officials, who are now watching to make sure an outbreak does not become an epidemic.
But now, reports NPR’s Michaeleen Doucleff, there’s a new tool available in the fight against the deadly virus: the Ebola vaccie. And the Democratic Republic of Congo has agreed to use it.
The highly effective vaccine, rVSV-ZEBOV, was recently tested in Guinea. When the trial started in 2015, outbreaks of the virus were still happening in the region. According to the World Health Organization, the 5,837 people who were vaccinated did not contract Ebola, while people in the same area who did not receive it did. Ira Longini, a biostatistician who helped test the vaccine, tells Doucleff that while the efficacy was 100 percent during the trial, the vaccine is likely between 70 and 100 percent effective.
As Smithsonian.com reported earlier this month, Ebola returned to the Democratic Republic of Congo in late April when a group of people in a remote area were stricken with hemorrhagic fever. According to the most recent World Health Organization update, there have been a total of two confirmed, three probable and 12 suspected cases thus far.
Gavi, the Vaccine Alliance, a public-private global health partnership that focuses on immunizations in poor countries, committed to purchasing the vaccine before it was licensed, Nature’s Erika Check Hayden reported last year. Merck, the vaccine’s manufacturer, provided a stockpile of 300,000 doses of the vaccine.
Saving all of those vaccines for a rainy day seems to have worked: Now, the vaccine is available for use where it’s needed. However, the vaccine is still technically experimental and, Reuters reports, will only be used if someone outside the known chain of transmission is identified as having Ebola.
The known cases occurred in an extremely remote, forested area and it’s still unclear if the logistics of organizing a vaccination campaign and transporting the precious immunizations will be possible. Still, the existence of the vaccine and the willingness to deploy it if necessary is a relief—until the vaccine was developed, the only way to fight the disease was to isolate people from those infected with Ebola.