At least 2,000 people have died in the Ebola outbreak in the Democratic Republic of Congo, making it the fastest-growing outbreak on record, according to the latest government data. Health authorities said 4,381 confirmed cases have been reported across five provinces as of Tuesday. The outbreak has been difficult to contain because health workers struggle to reach remote localities due to rebel conflict, bad roads, and work stoppages over payment issues. In a related development, a clinical trial has been launched for the Zaire Ebolavirus vaccine Ervebo, which will be investigated against the current Bundibugyo strain. The vaccine trial comes as the outbreak continues to spread, with the death toll rising steadily. Authorities have not said how many of the confirmed cases have recovered, and the outbreak shows no sign of slowing.