Health workers go door-to-door on the outskirts of Pakistan's Mardan city, dripping bitter doses of polio vaccine into infants' mouths. The last infection of the wild poliovirus was recorded on January 27, 2021, according to officials, and Friday marks the first time in Pakistan's history that a year has passed with no new cases. To formally eradicate the disease, a nation must be polio-free for three consecutive years -- but even 12 months is a long time in a country where vaccination teams are in the crosshairs of a simmering insurgency. Since the Taliban takeover of neighbouring Afghanistan, the Pakistan version of the movement has become emboldened and its fighters frequently target polio teams. "Life or death is in God's hands. We have to come, we can't just turn back because it's difficult," says Sidra Hussain, a health worker involved in the door-to-door vaccination programme. IMAGES AND SOUNDBITES