Uganda started an Ebola Sudan virus vaccination trial on Monday, four days after an outbreak was confirmed, the WHO announced, beginning with those deemed at highest risk of the disease.

“This vaccination trial was initiated with record speed… while ensuring full compliance with international and national regulatory and ethical requirements. It is also the first trial to assess the clinical efficacy of a vaccine against Ebola Sudan virus disease,” World Health Organization chief Tedros Adhanom Ghebreyesus said on X.