Now, those workers have become quarry. After militants stalked and killed eight of them over the course of a three-day, nationwide vaccination drive, the United Nations suspended its anti-polio work in Pakistan on Wednesday, and one of Pakistan’s most crucial public health campaigns has been plunged into crisis.
The World Health Organization and Unicef ordered their staff members off the streets, while government officials reported that some polio volunteers — especially women — were afraid to show up for work.
At the ground level, it is those female health workers who are essential, allowed privileged entrance into private homes to meet and help children in situations denied to men because of conservative rural culture. “They are on the front line; they are the backbone,” said Imtiaz Ali Shah, a polio coordinator in Peshawar.
The killings started in the port city of Karachi on Monday, the first day of a vaccination drive aimed at the worst affected areas, with the shooting of a male health worker. On Tuesday four female polio workers were killed, all gunned down by men on motorcycles in what appeared to be closely coordinated attacks.
The hit jobs then moved to Peshawar, the capital of Khyber-Pakhtunkhwa Province, which, along with the adjoining tribal belt, constitutes Pakistan’s main reservoir of new polio infections. The first victim there was one of two sisters who had volunteered as polio vaccinators. Men on motorcycles shadowed them as they walked from house to house. Once the sisters entered a quiet street, the gunmen opened fire. One of the sisters, Farzana, died instantly; the other was uninjured.
On Wednesday, a man working on the polio campaign was shot dead as he made a chalk mark on the door of a house in a suburb of Peshawar. Later, a female health supervisor in Charsadda, 15 miles to the north, was shot dead in a car she shared with her cousin.
Yet again, Pakistani militants are making a point of attacking women who stand for something larger. In October, it was Malala Yousafzai, a schoolgirl advocate for education who was gunned down by a Pakistani Taliban attacker in the Swat Valley. She was grievously wounded, and the militants vowed they would try again until they had killed her. The result was a tidal wave of public anger that clearly unsettled the Pakistani Taliban.
In singling out the core workers in one of Pakistan’s most crucial public health initiatives, militants seem to have resolved to harden their stance against immunization drives, and declared anew that they consider women to be legitimate targets. Until this week, vaccinators had never been targeted with such violence in such numbers.
Government officials in Peshawar said that they believe a Taliban faction in Mohmand, a tribal area near Peshawar, was behind at least some of the shootings. Still, the Pakistani Taliban have been uncharacteristically silent about the attacks, with no official claims of responsibility. In staying quiet, the militants may be trying to blunt any public backlash like the huge demonstrations over the attack on Ms. Yousafzai.
Female polio workers here make for easy targets. They wear no uniform but are readily recognizable, with clipboards and refrigerated vaccine boxes, walking door to door. They work in pairs — including at least one woman — and are paid just over $2.50 a day. Most days one team can vaccinate 150 to 200 children.
Faced with suspicious or recalcitrant parents, their only weapon is reassurance: a gentle pat on the hand, a shared cup of tea, an offer to seek religious assurances from a pro-vaccine cleric. “The whole program is dependent on them,” said Mr. Shah, in Peshawar. “If they do good work, and talk well to the parents, then they will vaccinate the children.”
That has happened with increasing frequency in Pakistan over the past year. A concerted immunization drive, involving up to 225,000 vaccination workers, drove the number of newly infected polio victims down to 52. Several high-profile groups shouldered the program forward — at the global level, donors like the Bill and Melinda Gates Foundation, the United Nations and Rotary International; and at the national level, President Asif Ali Zardari and his daughter Aseefa, who have made polio eradication a “personal mission.”
On a global scale, setbacks are not unusual in polio vaccination campaigns, which, by dint of their massive scale and need to reach deep inside conservative societies, end up grappling with more than just medical challenges. In other campaigns in Africa and South Asia, vaccinators have grappled with natural disaster, virulent opposition from conservative clerics and sudden outbreaks of mysterious strains of the disease.
Declan Walsh reported from Lahore, and Donald G. McNeil Jr. from New York. Ismail Khan contributed reporting from Peshawar, Pakistan.