Islamabad , Pakistan ( CNN ) -- Health workers administering polio vaccinations came under fresh attack in Pakistan on Wednesday , a troubling development in a nation that remains one of three in the world where the disease has yet to be eradicated . Three workers were killed in separate attacks , a day after five others died in similar circumstances . All of them were part of a massive vaccination campaign nationwide . The attacks prompted authorities to suspend the campaign throughout the country . Read more : At the U.N. , a vow to eradicate polio by 2015 . In Wednesday 's attacks : . -- Two men opened fire on an 18-year-old worker as he was vaccinating children on the outskirts of the northwestern city of Peshawar . The worker died of bullet wounds to the head , said Dr. Janbaz Afridi , the provincial director of the polio campaign . -- Gunmen opened fire on a car carrying a vaccination campaign supervisor and her driver in Charsadda -- killing them both . -- Also in Charsadda , two female workers narrowly escaped when some men began shooting at them . -- Three other female workers also escaped unhurt when they were shot at in Nowshera district . All the attacks Wednesday took place in Khyber Pakhtunkhwa , a province rife with Islamic extremists . On Tuesday , five workers were killed : four in Karachi ; and a 14-year-old volunteer in Peshawar as she and her sister were leaving a house after administering vaccines . Pakistanis have viewed polio vaccination campaigns with suspicion after the CIA 's use of a fake vaccination program last year to collect DNA samples from residents of Osama bin Laden 's compound to verify the al Qaeda leader 's presence there . Bin Laden was killed by U.S. forces in May 2011 . In June , a Taliban commander in northwest Pakistan announced a ban on polio vaccines for children in the region as long as the United States continues its campaign of drone strikes in the region , the Taliban said . CNN was not able to reach the Taliban for comment regarding the latest attacks . Polio , a highly infectious viral disease that can cause permanent paralysis in a matter of hours , has been eradicated around the world except for three countries where it is endemic : Pakistan , Nigeria and Afghanistan . After the number of cases spiked sharply last year , Pakistan stepped up its eradication efforts . The numbers fell from 173 last year to 53 this year , according to the Global Polio Eradication Initiative .
Four attacks take place on Wednesday , killing three workers . On Tuesday , five workers are killed . Pakistanis have viewed polio vaccination campaigns with suspicion .