CDC Director Dr. Thomas Frieden said Tuesday on “The Kelly File” that Ebola protocols are being improved after a Texas nurse contracted the deadly disease while caring for a patient, acknowledging something “clearly” went wrong in that case.

“We know how Ebola spreads, we know how to stop it from spreading,” Frieden told Fox News’ Megyn Kelly. “But clearly what happened at the hospital shouldn’t have happened. So we’re now looking at that and saying okay, what’s everything we can do to ensure that anytime someone is caring for Ebola their risk is kept to an absolute minimum.”

Frieden said the CDC is taking new steps to ensure the virus does not spread to any more people in the U.S. First, he said the CDC is working to ensure the Texas patient, Nina Pham, receives “safe and effective” care. In addition, Frieden said if any other Ebola cases are confirmed, the CDC will provide Ebola response teams within hours.

He said the agency is also encouraging doctors at all hospitals to “think Ebola” when patients present with symptoms.

Frieden has been criticized for insisting, shortly before Pham was diagnosed, that "virtually any hospital in the country that can do isolation can do isolation for Ebola” and that Ebola would be stopped in its tracks in the U.S.

In response to that criticism, Frieden called Pham's case “terrible.”

“But what we’re doing is making sure that we stop the chain of transmission,” he said. “I think you have to step back and say: who’s really at risk here? Well, in West Africa there is a lot of risk. For health care workers who are caring for Ebola patients there is risk and we’ll work to minimize that and get it as low as possible.”

Frieden insisted that a mandatory travel ban would not be effective in countering the disease, saying a ban would only make the epidemic worse in Africa.

“If we isolate these countries what’s not going to happen is disease staying there,” he said. “It’s going to spread more all over Africa and we’ll be at higher risk.”

Despite the recent cases, Frieden said the chances of an Ebola outbreak in the U.S. are very slim.

“There is no doubt of my mind that we will not have a large outbreak of Ebola in the U.S.,” he said.