Africa¡¯s top public health official said the latest Ebola outbreak in eastern Congo is being fought without one of the most important tools in epidemic response: vaccines.

Jean Kaseya, director-general of the Africa Centres for Disease Control and Prevention, said response efforts to the disease are now heavily dependent on community outreach and behavioral change campaigns to slow transmission.

The outbreak, now the ¡°second largest¡± after the 2014-2016 West Africa epidemic, is caused by the rare Bundibugyo strain of the virus and has no approved vaccine or antibody treatment. Kaseya said hopes that existing vaccine options could provide even partial protection have faded in recent weeks.