The World Health Organization has declared an Ebola outbreak in the Democratic Republic of Congo “largely contained” less than two months after it began thanks to a new vaccine and rapid-response medical units. After the first cases of Ebola were confirmed in on May 8, more than 3,200 people were vaccinated with a new Merck vaccine that was first tested in the wake of the 2014 epidemic. The Congolese health ministry has said none of those vaccinated were infected, and as of Tuesday, no confirmed cases of the virus have been reported since June 6. The WHO said 1,500 contacts of confirmed or probable cases were monitored for 21 days—the maximum incubation period—and had not shown any signs of the virus. Rapid response medical teams had acted swiftly to stop the virus from spreading, deploying the new vaccine to the heavily populated river port city of Mbandaka almost immediately after cases were confirmed there.