WASHINGTON, DC - JULY 13: Central Intelligence Agency Director John Brennan discusses his agency's strategy in the face of emerging challenges during an event at the Brookings Institution July 13, 2016 in Washington, DC. Brennan said, although "enhanced interrogation techniques" employed after the attacks of 9/11 did reveal usable intelligence, he would not lead the CIA if a new president were to order EIT used again. (Photo by Chip Somodevilla/Getty Images)

WASHINGTON, DC - JULY 13: Central Intelligence Agency Director John Brennan discusses his agency's strategy in the face of emerging challenges during an event at the Brookings Institution July 13, 2016 in Washington, DC. Brennan said, although "enhanced interrogation techniques" employed after the attacks of 9/11 did reveal usable intelligence, he would not lead the CIA if a new president were to order EIT used again. (Photo by Chip Somodevilla/Getty Images)

WASHINGTON, DC - JULY 13: Sen. Elizabeth Warren (D-MA), (L) is seen on a monitor delivering a speech about the American middle class, while Democratic Presidential candidtate Hillary Clinton is also seen on a monitor, at a Center for American Progress (CAP) forum, July 13, 2016 in Washington, DC. (Photo by Mark Wilson/Getty Images)

WASHINGTON, DC - JULY 13: Center for Disease Control Director Tom Frieden participates in a discussion about 'Zika, the Olympics, and Global Health Security: A Marathon Against a Microbe' at New America July 13, 2016 in Washington, DC. Frieden said that the CDC's response to the Zika virus has been the most complex he has overseen, with more than 1000 employees working across many departments. 'Congress did the right thing with Ebola,' Frieden said. 'I hope they do the same with Zika funding as well. But speed is of the essence.' (Photo by Chip Somodevilla/Getty Images)

WASHINGTON, DC - JULY 13: Center for Disease Control Director Tom Frieden (L) answers audience questions during a discussion about the Zika virus with former U.S. Assistant Surgeon General Susan Blumenthal at New America July 13, 2016 in Washington, DC. Frieden said that the CDC's response to the Zika virus has been the most complex he has overseen, with more than 1000 employees working across many departments. 'Congress did the right thing with Ebola,' Frieden said. 'I hope they do the same with Zika funding as well. But speed is of the essence.' (Photo by Chip Somodevilla/Getty Images)

WASHINGTON, DC - JULY 13: Center for Disease Control Director Tom Frieden participates in a discussion about 'Zika, the Olympics, and Global Health Security: A Marathon Against a Microbe' at New America July 13, 2016 in Washington, DC. Frieden said that the CDC's response to the Zika virus has been the most complex he has overseen, with more than 1000 employees working across many departments. 'Congress did the right thing with Ebola,' Frieden said. 'I hope they do the same with Zika funding as well. But speed is of the essence.' (Photo by Chip Somodevilla/Getty Images)

WASHINGTON, DC - JULY 13: Center for Disease Control Director Tom Frieden reacts while telling a story about Zika virus response in Puerto Rico during a discussion with former U.S. Assistant Surgeon General Susan Blumenthal at New America July 13, 2016 in Washington, DC. Frieden said that the CDC's response to the Zika virus has been the most complex he has overseen, with more than 1000 employees working across many departments. 'Congress did the right thing with Ebola,' Frieden said. 'I hope they do the same with Zika funding as well. But speed is of the essence.' (Photo by Chip Somodevilla/Getty Images)

WASHINGTON, DC - JULY 13: Center for Disease Control Director Tom Frieden participates in a discussion about 'Zika, the Olympics, and Global Health Security: A Marathon Against a Microbe' at New America July 13, 2016 in Washington, DC. Frieden said that the CDC's response to the Zika virus has been the most complex he has overseen, with more than 1000 employees working across many departments. 'Congress did the right thing with Ebola,' Frieden said. 'I hope they do the same with Zika funding as well. But speed is of the essence.' (Photo by Chip Somodevilla/Getty Images)