Athar Hussain/Reuters
Relatives of Nasima Bibi, a worker in a polio vaccination drive, at a hospital morgue in Karachi.
ISLAMABAD, Pakistan — Gunmen shot dead five female health workers who were immunizing children against polio on Tuesday, causing the Pakistani government to suspend vaccinations in two cities and dealing a fresh setback to an eradication campaign dogged by Taliban resistance in a country that is one of the disease’s last global strongholds.
“It is a blow, no doubt,” said Shahnaz Wazir Ali, an adviser on polio to Prime Minister Raja Pervez Ashraf. “Never before have female health workers been targeted like this in Pakistan. Clearly there will have to be more and better arrangements for security.”
No group claimed responsibility for the attacks, but most suspicion focused on the Pakistani Taliban, which has previously blocked polio vaccinators and complained that the United States is using the program as a cover for espionage.
The killings were a serious reversal for the multibillion-dollar global polio immunization effort, which over the past quarter century has reduced the number of endemic countries from 120 to just three: Pakistan, Afghanistan and Nigeria.
Nonetheless, United Nations officials insisted that the drive would be revived after a period for investigation and regrouping, as it had been after previous attacks on vaccinators here, in Afghanistan and elsewhere.
Pakistan has made solid gains against polio, with 56 new recorded cases of the diseases in 2012, compared with 192 at the same point last year, according to the government. Worldwide, cases of death and paralysis from polio have been reduced to less than 1,000 last year, from 350,000 worldwide in 1988.
But the campaign here has been deeply shaken by Taliban threats and intimidation, though several officials said Tuesday that they had never seen such a focused and deadly attack before.
Insurgents have long been suspicious of polio vaccinators, seeing them as potential spies. But that greatly intensified after the C.I.A. used a vaccination team headed by a local doctor, Shakil Afridi, to visit Osama bin Laden’s compound in Abbottabad, reportedly in an attempt to obtain DNA proof that the Bin Laden family was there before an American commando raid on it in May 2011.
In North Waziristan, one prominent warlord has banned polio vaccinations until the United States ceases drone strikes in the area.
Most new infections in Pakistan occur in the tribal belt and adjoining Khyber-Pakhtunkhwa Province — some of the most remote areas of the country, and also those with the strongest militant presence. People fleeing fighting in those areas have also spread the disease to Karachi, the country’s largest city, where the disease has been making a worrisome comeback in recent years.
After Tuesday’s attacks, witnesses described violence that was both disciplined and well coordinated. Five attacks occurred within an hour in different Karachi neighborhoods. In several cases, the killers traveled in pairs on motorcycle, opening fire on female health workers as they administered polio drops or moved between houses in crowded neighborhoods.
Of the five victims, three were teenagers, and some had been shot in the head, a senior government official said. Two male health workers were also wounded by gunfire; early reports incorrectly stated that one of them had died, the official said.
In Peshawar, the capital of Khyber-Pakhtunkhwa Province, gunmen opened fire on two sisters participating in the polio vaccination program, killing one of them. It was unclear whether that shooting was directly linked to the Karachi attacks.
In remote parts of the northwest, the Taliban threat is exacerbated by the government’s crumbling writ. In Bannu, on the edge of the tribal belt, one polio worker, Noor Khan, said he quit work on Tuesday once news of the attacks in Karachi and Peshawar filtered in.
“We were told to stop immediately,” he said by phone.
Still, the Pakistani government has engaged considerable political and financial capital in fighting polio. President Asif Ali Zardari and his daughter Aseefa have been at the forefront of immunization drives. With the help of international donors, including the Bill and Melinda Gates Foundation, they have mounted a huge vaccination campaign aimed at up to 35 million children younger than 5, usually in three-day bursts that can involve 225,000 health workers.
The plan seeks to have every child in Pakistan immunized at least four times per year, although in the hardest-hit areas one child could be reached as many as 12 times in a year.
