Health authorities in the Democratic Republic of Congo began vaccinating the first trial participants Sunday in a major clinical study of next-generation Ebola vaccines. The trial opened days after the outbreak centered in Equateur province continued spreading through rural health zones, and the World Health Organization confirmed enrollment.

Coordinated with the DR Congo health ministry and supported by the WHO and vaccine alliance Gavi, the trial is evaluating candidates beyond Merck's licensed Ervebo vaccine. The DR Congo health ministry launched the study on October 23 as confirmed and probable cases rose past 50, with multiple deaths among health workers and family contacts.

A WHO Africa regional office spokesperson said ring vaccination of contacts was running in parallel with the trial to contain transmission. The outbreak is the latest in a country that has recorded more Ebola epidemics than any other nation.

Jean Kaseya, director-general of the Africa Centres for Disease Control and Prevention, has urged donors to maintain emergency funding as competing health crises strain regional resources. "Every day counts in an Ebola response, and vaccinating contacts quickly is our strongest tool," the WHO spokesperson said. "This trial gives us the chance to test new options while protecting communities now."