Pakistani police say unidentified gunmen shot and killed a police officer working on Pakistan’s first polio vaccination drive of the year.

Officials say Pakistan has begun its last nationwide vaccination campaign for the year to protect 45 million children from polio after a surge in new cases hampered efforts to stop the disease.

Pakistan has begun a nationwide vaccination campaign to protect 45 million children from polio after a surge in new cases that has hampered years of efforts to stop the disease in one of the two countries where it has never been eradicated.