A World Health Organization (WHO) worker administers a vaccination during the launch of a campaign against an outbreak of Ebola in the port city of Mbandaka, Democratic Republic of Congo, May 21, 2018.

A World Health Organization (WHO) worker administers a vaccination during the launch of a campaign against an outbreak of Ebola in the port city of Mbandaka, Democratic Republic of Congo, May 21, 2018.

© 2018 Kenny Katombe/Reuters