PESHAWAR, Pakistan — Gunmen shot and killed a woman working on U.N.-backed polio vaccination efforts and her driver in northwestern Pakistan on Wednesday, officials said, raising to eight the number of people killed in 48 hours who were part of the immunization drive.
The attack on the woman was one of five Wednesday on polio workers in northwestern Pakistan. On Tuesday, gunmen killed five female polio workers, three of them teenagers, in a series of attacks in Karachi.
The killings prompted the U.N.'s public health arm to suspend work on the vaccination drive in two of Pakistan's four provinces Wednesday, a major setback for a campaign that international health officials consider vital to contain the crippling disease.
No group has claimed responsibility for the attacks. Suspicion has fallen on the Pakistani Taliban because of their opposition to the polio campaign, but the group's spokesman, Ahsanullah Ahsan, denied responsibility in a telephone call to the Associated Press. Police say they have killed two militant suspects and arrested a dozen others in connection with the attacks.
Pakistan is one of only three countries where polio is endemic. Prevention efforts have managed to reduce the number of cases in Pakistan by about 70 percent this year compared with 2011. But the recent violence threatens to reverse that progress.
The unprecedented number of attacks on polio workers came as the government started a three-day vaccination drive Monday targeting high-risk areas of the country, part of an effort to immunize millions of children under age 5.
Militants accuse health workers of acting as spies for the United States and claim the vaccine makes children sterile. Taliban commanders in the troubled northwest tribal region have also said vaccinations can't go forward until U.S. drone strikes stop.
Insurgent opposition to the campaign grew last year after it was revealed that a Pakistani doctor ran a fake vaccination program to help the CIA track down al-Qaida chief Osama bin Laden.