President Obama's top counterterrorism advisor has vowed that the CIA will no longer be able to use vaccination programs as cover for intelligence operations like those the agency carried out prior to the killing of Usama bin Laden in 2011.

Lisa Monaco announced the policy change last week in a letter to the deans of 13 schools of public health. Monaco's letter said that the CIA has agreed to stop using vaccination programs and workers for intelligence purposes. The agency has also agreed not to use genetic material obtained through such programs.

The educators had written to Obama last year protesting the use of immunization programs as a front for espionage. The most prominent program was run by Dr. Shakil Afridi, who offered hepatitis vaccinations in the Pakistani city of Abbottabad as cover for his CIA-backed effort to obtain DNA samples from children at a compound where bin Laden was later killed during a 2011 raid by U.S. Navy SEALs. Afridi was convicted and sentenced by a Pakistani court to 33 years in prison for treason. The sentence was later overturned and Afridi faces a retrial.

In 2012, the United Nations suspended a polio vaccination effort in Pakistan after gunmen killed several health workers. Taliban militants accused health workers of acting as spies for the U.S.

In the May 16 letter, Monaco said the U.S. "strongly supports the Global Polio Eradication Initiative and efforts to end the spread of the polio virus forever."

She added that CIA Director John Brennan said in August 2013 that the agency would "make no operational use of vaccination programs, which includes vaccination workers." Also saying no DNA or genetic material from such programs would be used, Monaco said the CIA policy "applied worldwide and to U.S. and non-U.S. persons alike."

CIA spokesman Dean Boyd said Brennan "took seriously the concerns raised by the public health community, examined them closely and took decisive action."

Monaco's letter and the CIA statement did not acknowledge any error in the decision to use the Pakistan vaccine program as a spying cover. The letter was first disclosed in a report by Yahoo News.

The White House statement came three days after Pakistan acted to quell a growing polio crisis within its borders. The public health deans had warned last year that the CIA's use of a vaccination program had played a role in the shootings of several health workers in Pakistan and could hamper anti-polio efforts.

"Public health programs should not be used as cover for covert operations," they said.

Last week, Pakistan's Health Ministry announced that it would require that all travelers leaving the country first get a polio vaccination. That move followed the World Health Organization's declaration earlier this month that polio's spread was an international public health emergency. The WHO identified Pakistan, Syria and Cameroon as nations that had allowed polio to spread beyond their borders.

Pakistan was the only country with reported endemic polio that saw a rise in new cases in 2012, the health organization reported. Pakistan accounted for more than a fifth of all polio cases identified across the world in 2013.

The CIA's use of a vaccine program to spy on bin Laden's compound undercut Obama's own high-profile speech to the Muslim world in 2009, in which he touted U.S. efforts to slash the growth of polio in Pakistan, Afghanistan and Nigeria. With Obama administration assurances, Muslim scholars in two international groups issued religious decrees urging parents to vaccinate their children.

The Associated Press contributed to this report.