A new case of Ebola has been recorded in the Democratic Republic of the Congo (DRC). It was the first such report in 52 days, and came just two days before the WHO was set to declare the official end of the outbreak.

Already, clinicians and scientists on the frontline of that crisis have shifted their attention to COVID-19. But now, their efforts at the site of the Ebola outbreak must continue, too.

“I am so sad,” says Marie-Roseline Darnycka Bélizaire , an epidemiologist who has coordinated the WHO’s Ebola response in northeastern DRC for two years.

Experts have called the Ebola outbreak, which started in August 2018, one of the most complex health emergencies the world has ever seen because it occurred in a region of the DRC ravaged by decades of war and political instability. More than 2,270 people have died of Ebola — around two-thirds of the outbreak’s reported infections. In addition, more than 70 responders and people with the disease were injured in targeted attacks by armed groups.

Cases began dwindling in January this year, and until today, the most recent person with the disease was diagnosed on 17 February. She survived, and was discharged from the hospital on 3 March. In the 40 days that followed, more than 2,000 people had been tested for Ebola, and no new cases had come to light—until now. This case means that the 42-day count-down to an official declaration of victory must begin again.

Yesterday, when it seemed the outbreak was nearly over, Bélizaire said she felt an “indescribable joy.” Today, she says, “I expected a sporadic case earlier, but not two days before the end.”