Ebola Vaccine tested on the monkeys in Bethesda in Washington, United States on November 22, 2000. [Getty Images]

UNITED STATES - NOVEMBER 22: Ebola Vaccine tested on the monkeys in Bethesda in Washington, United States on November 22, 2000 - Taking of a sample of "naked" DNA vaccine PGP/NP before inserting it into the Biojector (Photo by Raphael GAILLARDE/Gamma-Rapho via Getty Images)

Gamma-Rapho Raphael GAILLARDE