vaccine

A health worker administers a polio vaccine to a child, in Enjil district of Herat, Afghanistan, 11 May 2015. Pakistan, Nigeria and Afghanistan are considered to be the only countries where the poliovirus is still endemic.

Jalil Rezayee/EPA

A health worker administers a polio vaccine to a child, in Enjil district of Herat, Afghanistan on Monday. Pakistan, Nigeria and Afghanistan are considered to be the only countries where the poliovirus is still endemic

An Afghan health worker administers polio vaccine drops to a child on the second day of a vaccination campaign in Kabul on March 16, 2015. Nearly nine million children throughout Afghanistan will be immunized during a three-day national polio immunization drive launched on March 15.The immunization campaign comes shortly after Afghanistan reported its first case of polio virus for 2015, in Helmand, in the Southern Region. Afghanistan and Pakistan are the only two countries in the world to have reported cases of the crippling polio virus in the past eight months and it is increasingly likely that these are the last two countries on Earth with active polio transmission

Shah Marai/AFP

A health worker gives polio vaccine drops to a child on the second day of a national campaign in Afghanistan on Monday. Nearly nine million children in the country are being immunised during the three-day programme.

A local health worker administers a vaccine at a local health center at the financial district of Makati, east of Manila, Philippines, Friday, Sept. 12, 2014. The World Health Organization and the British government are working with the Philippine Department of Health, UNICEF and a host of other partners to help deliver a month-long campaign to immunize children against Measles, Rubella, commonly known as German measles, and Polio which aims to immunize 13 million children nationwide. (AP Photo/Bullit Marquez)

Bullit Marquez/AP

A local health worker administers a vaccine at a local health centre at the financial district of Makati, Manila

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

A Pakistani boy suffering from Measles lies asleep after getting vaccinated at a medical camp in Peshawar, Pakistan, 26 April 2013. Pakistani health authorities were scrambling to vaccinate thousands of children across the country after a measles outbreak. Measles was suspected to be the main cause for dozens of deaths last year in Sindh, Punjab, Balochistan and Khyber Pakhtunkhwa provinces, with most children dying because of post-measles complications, including pneumonia and diarrhea, according to media report.

Arshad Arbab/EPA

A Pakistani boy suffering from Measles lies asleep after getting vaccinated at a medical camp in Peshawar, Pakistan, on Friday. Pakistani health authorities were scrambling to vaccinate thousands of children across the country after a measles outbreak. Measles was suspected to be the main cause for dozens of deaths last year in Sindh. 

Pakistani health worker Salma Saleem, right, marks the finger of a child after giving him a polio vaccine

Muhammed Muheisen/AP Photo

Pakistani health worker Salma Saleem, right, marks the finger of a child after giving him a polio vaccine in a neighborhood in Islamabad, Pakistan on April 15 2013. In December, gunmen killed nine polio workers in different parts of Pakistan. Several more workers have been killed since then, as well as policemen who were protecting them. The UN said last month that some 240,000 children missed vaccinations since July in parts of Pakistan’s tribal region, the main sanctuary for Islamic militants, because of security concerns.