By Geoff Brumfiel of Nature magazine

Did the United States organize a fake vaccine campaign in Pakistan to try and ensnare the world's top terrorist? In true spook fashion, the Central Intelligence Agency (CIA) isn't saying, but the rumor alone could set back already fragile vaccination efforts in the troubled nation of 180 million, according to public-health researchers from the region.

The story, which first appeared in The Guardian on Monday, alleges that the CIA sent vaccinators into the Pakistani city of Abbottabad in the months before the raid by US special forces that killed Osama bin Laden. The vaccination campaign, for hepatitis B, went door-to-door, with the hopes of gathering DNA from one of bin Laden's children to verify the location of his compound. A nurse reportedly entered the compound with an electronic device, though it is unclear whether DNA was gathered, or whether the device remained behind. Marie Harf, a CIA spokeswoman, declined to comment on the alleged plot.

Vaccination backlash

Regardless of their veracity, the reports have the potential to do real damage to public-health efforts in Pakistan, which is one of just four countries in which the polio virus is still endemic. "It will create a huge backlash against the polio eradication program," warns Anita Zaidi, chairwoman of the department of pediatrics and child health at Aga Khan University in Karachi. Zaidi says that she is "extremely disturbed" by the rumor, especially as she and others depend on US funding to conduct their activities.

The alleged ring-leader of the CIA plot was a surgeon called Shakil Afridi. Afridi worked in Khyber Agency, part of the Federally Administered Tribal Areas, a remote and loosely controlled region on the Afghan border. Muslim extremist groups such as the Taliban have used the area as a base for operations.

Just like the extremists, "polio has been given a safe haven in the frontier," says Haider Warraich, a research fellow at Beth Israel Deaconess Medical Center in Boston, Massachusetts, who until last year worked with Zaidi in Karachi. Vaccinators face mistrust from locals, who often believe rumors that vaccinations are part of a Western sterilization campaign against Muslims. In 2007, local Taliban leaders assassinated Abdul Ghani Marwat, the head of a vaccination campaign in Bajaur Agency, and Warraich says that workers regularly face death threats and kidnappings.

Refugees and migrants from the tribal areas carry disease into cities such as Abbottabad, which lies just 50 kilometers from the Pakistani capital Islamabad. Warraich says he is concerned that the latest story, which has been widely reported in Pakistan, will discourage city dwellers from participating in vaccination campaigns that are crucial in preventing the further spread of infections in crowded cities. In addition to polio, Pakistan has one of the highest rates of measles in the world. The World Health Organization (WHO) estimates that around 20,000 Pakistani children die from measles each year, many of them in urban slums.

Not everyone agrees that the latest rumor will do any more damage. Mistrust in the tribal regions was already high, says Aziz Memon, the national head of Rotary International's polio eradication campaign in Pakistan. "This is not going to add any new flavor to it," he says. Memon says that his organization and others are working closely with religious leaders in Abbottabad and other cities to promote their vaccination campaigns, and he expects that the latest story will not undermine the relationships they have developed.

Rumors or not, polio continues to spread in Pakistan, according to the WHO. Already this year, 59 children have been paralyzed by the virus.

This article is reproduced with permission from the magazine Nature. The article was first published on July 14, 2011.