Vaccination against ebola virus in Kirembo village
A Ugandan health worker prepares to administer the ebola vaccine to a man in Kirembo village, near the border with the Democratic Republic of Congo in Kasese district, Uganda, June 16, 2019. Reuters

The United States sent Gilead Sciences' remdesivir and Mapp Biopharmaceutical Inc's experimental Ebola antibody drug MBP134 to Uganda last week to help safeguard healthcare workers responding to an outbreak that has infected 60 people and killed 44, U.S. government sources told Reuters.

There are currently no proven vaccines or treatments for the Sudan species of Ebola, one of four known Ebola viruses to cause hemorrhagic fever in humans. The outbreak confirmed by the Ugandan health ministry on Sept. 20 is the largest of the Sudan species since 2000.

Uganda health minister Jane Ruth Aceng disclosed the U.S. shipments at a meeting of African region health officials last week in Kampala and said remdesivir, which has been widely used as a COVID-19 treatment, and an undisclosed monoclonal antibody had been given to healthcare workers.

Providing treatment that protects the lives of healthcare workers could be central to containing the outbreak, said Joel Montgomery, the U.S. Centers for Disease Control and Prevention's chief of the viral special pathogens branch and incident manager for the outbreak.

"If healthcare workers start to fall ill and die, it's going to negatively impact the response," said Montgomery, who had just returned from a trip to Uganda.

For instance, healthcare workers may be reluctant to assist in the response, he said in a phone interview.

The World Health Organization said in a statement the agency is working with partners in Uganda to set up the infrastructure for a clinical trial and is supporting use of the untested antivirals and monoclonal antibodies and will collect data on their efficacy.

A large outbreak of the Zaire species of Ebola in West Africa from 2014-2016 led to effective vaccines and treatment, but there are no proven treatments or vaccines for the Sudan species.

San Diego-based Mapp Biopharmaceutical received a $110 million contract from the U.S. government's Biomedical Advanced Research and Development Authority (BARDA) on Oct. 4 for advanced development and potential purchases of MBP134, a combination of monoclonal antibodies.

Gilead did not immediately respond to a request for comment.

A study of MBP134 and remdesivir in non-human primates showed that either drug given individually rescued 20% of animals infected with the Sudan species of Ebola, but when given in combination, 80% of infected animals survived.

MBP134 is currently being tested in early safety trials in healthy human volunteers, Mapp President Larry Zeitlin said in an email. All participants have completed the study, and the data are currently being analyzed. Overall, MBP134 was well tolerated, he said.

Zeitlin said when requested, the company does provide its drug for free for compassionate use, pending regulatory and ethics approvals. He declined to say how many doses the company provided.