immunisation

A health worker gives polio vaccine drops to a boy in an outskirt of the Yemeni capital Sanaa

Khaled Abdullah/Reuters

A health worker gives polio vaccine drops to a boy on the outskirts of Sanaa, the Yemeni capital, on Monday.

An Afghan health worker (2R) administers a polio vaccination to a child on the first day of a vaccination campaign in Herat. A new three-day nationwide immunisation campaign against polio began supported by Afghanistan's Ministry of Public Health country wide, officials said.

Aref Karimi/AFP

A health worker administers a polio vaccination to a child in Herat, Afghanistan, at the start of a three-day nationwide immunisation campaign against polio, supported by the country’s Ministry of Public Health