As more potentially infected individuals have emerged from quarantine and treatment in the U.S., in recent days, the Centers for Disease Control and Prevention has issued a new set of protocols designed to reduce risk for health care workers. And the Department of Homeland Security announced today it will allow travelers from Liberia, Sierra Leone and Guinea to enter the country only through five airports equipped for additional screening.

　　This evening, I spoke with Dr. Thomas Frieden, the director of the CDC.

　　Dr. Frieden, thank you for joining us again.

　　We have had some interesting news the past few days, the news of the end of the Ebola epidemic in Nigeria at least, the release of people from quarantine in Dallas, and just this afternoon we were hearing the upgraded condition of one of the nurses who was infected in Dallas.

　　Now I'm wondering whether it's too soon to be getting optimistic about the course of this infection.

　　DR. THOMAS FRIEDEN, Director, Centers for Disease Control and Prevention: We have to keep our guard up.

　　There are still thousands of cases in West Africa. The epidemic is still increasing in Sierra Leone and parts of Guinea. And there's — there's no time for complacency. We absolutely need to keep our guard up.

　　GWEN IFILL: Can we talk about the new protocols you announced last night about — for health care workers and what difference they will make?

　　DR. THOMAS FRIEDEN: What we're doing is being more protective, adding a margin of safety, and doing that in three fundamental ways, first, ensuring that health care workers know what to do to put on and take of protective gear, so there's training and practice over and over again, so that it's done well.

　　Second, the gear that we're recommending now has no skin exposed to have that extra margin of safety. And, third, a trained observer watches and checks off each and every step putting on and taking off the gear. That's critically important to protect health care workers, because even a single infection is one infection too many.

　　GWEN IFILL: But these protocols are voluntary, are they not?

　　DR. THOMAS FRIEDEN: We find that the hospital generally follows CDC guideline. CDC is not a regulatory agency, but other parts of the federal government and states can impose regulations.

　　GWEN IFILL: Do these hospitals where this training is going to take effect, do they have even enough beds, enough isolation units for people?

　　DR. THOMAS FRIEDEN: The physical space is not the hardest part, though there are hard parts about that, because you need an anteroom or separate area to put on and take off the protective gear.

　　And it doesn't require special rooms. What it does require is special training, special equipment for protection and rigorous monitoring and oversight. This, we found in Africa and here. You need someone there full-time watching and checking to make sure that there are no missteps.

　　GWEN IFILL: But you don't need to have isolation areas, isolated rooms, isolated beds?

　　DR. THOMAS FRIEDEN: You do need a separate area to take care of patients with Ebola.

　　And there are a lot of complicated aspects of creating that. You need a clean area and a dirty area. You need an anteroom. You need a separate place for putting on and taking off the protective gear. With this new guideline, it becomes much more challenging and it requires a much more specialized approach for hospitals.

　　But every hospital, every emergency department in the country needs to think Ebola. For anyone with fever or other signs of infection, ask about travel history. Have you been to Guinea, Liberia or Sierra Leone in the past 21 days? And if they have, stop, isolate, assess, call for help.

　　GWEN IFILL: You talk about travel experience. Today, we heard from the Department of Homeland Security that they're going to limit the egress, I guess, the entrance to the United States to five airports from any of these three affected countries.

　　That would affect maybe nine people a day? What effect does that have?

　　DR. THOMAS FRIEDEN: That's actually very helpful for us, because at CDC what we have done is, working closely with Homeland Security and Border Protection, we're at each of these five airports with a team 24/7.

　　And what we do is ensure that every person coming in, they're initially screened by customs. And if they either have a fever or they have had contact with Ebola, they have come to us for tertiary screening. If we find anyone who has any symptoms — and we know we will pick up people with flu or cold or people who vomited on the plane because they felt bad. But if there's any suspicion of Ebola, then we will take them to a hospital that's prepared to deal with Ebola.

　　GWEN IFILL: There's been much conversation here in Washington about the appointment of what some people call an Ebola czar, what the White House calls an Ebola coordinator.

　　Two questions. Is that something which is needed? Is that helpful to you? And why aren't you the Ebola czar?

　　DR. THOMAS FRIEDEN: I'm delighted that there's an Ebola coordinator.

　　I'm looking forward to his visit to Atlanta next week. I have spoken with him already. And it's really important that we have coordination across the whole government. We can do the public health part at CDC, but there are so many aspects of this response that require a whole-of-government approach for accountability, coordination, liaison functions, troubleshooting.

　　There's been — everyone has been doing their part, but a coordinator allows us to do that more efficiently and effectively.

　　GWEN IFILL: And, finally, I want to ask you about the way the public has been reacting to all of this. There's a Gallup poll which says it's among the top 10 issues Americans worry about.

　　And there's a Pew poll that shows 41 percent say they worry that they or someone they know, some family member will be infected. Do they have reason to worry?

　　DR. THOMAS FRIEDEN: You know, it's hard to gauge risk sometimes, but, realistically, if you're a health care worker caring for one of the two patients with Ebola being cared for, three patients with Ebola being cared for in the U.S. today, you should be very careful.

　　If you are an emergency room doctor or nurse treating people with fever, you should think about Ebola. But, for everyone else, the risk of Ebola is really extraordinarily remote. But we can't let our guard down. As long as the outbreak continues in Africa, the risk of another traveler coming in of someone, responder going and back and getting it is there.

　　So it won't be zero until we stop the outbreak at the source in Africa.

　　GWEN IFILL: Thomas Frieden, executive director of the Centers for Disease Control and Prevention, thank you very much for joining us again.

　　DR. THOMAS FRIEDEN: Thank you.