We're going to start with the fresh cases of the bird flu virus. Look at this map. The bug spreading into new parts of china, hundreds of miles from the original hot zone. The head of the world health... See More
We're going to start with the fresh cases of the bird flu virus. Look at this map. The bug spreading into new parts of china, hundreds of miles from the original hot zone. The head of the world health organization saying he's not surprised by this. And abc's dr. Richard besser, former acting director of the cdc, is tracking all this from hong kong. Dr. Rich, why is the head of the w.H.O. Not surprised? And are you not surprised? Reporter: Dan, I'm not surprised, for a couple reasons. This virus does not harm birds. That would allow it to spread silently over a wide region of china and possibly beyond before it was detected. The second reason is, now that we know the cause of this, there's a diagnostic test. So, a lot of people with pneumonia, were in the past we might not know what caused it, they're being tested. I think we're going to see a lot more cases. We have a diagnostic test. Do we have a vaccine? And is that even possible? Reporter: Well, the news on that front is not very good. They're hard at work at it. But what I hear from experts is this type of bird flu virus, is notoriously hard to make a vaccine to. Cdc has a virus from china. They're working on it. It's not going to be easy. It's hard to make a virus -- make a vaccine, the virus is responding to early treatment. That's good news for people getting sick. And let me ask you one, quick question, rich. You're in hong kong. What is the mood like there? Are you starting to see any level of panic set in? I'm not seeing panic. Hong kong has dealt with bird flu before. I'm seeing a call in the newspapers for closure of the live bird markets. That was something they wanted to have done in the past. And now, with this new outbreak, they're calling for it again. Dr. Rich besser, the former acting director of the cdc, on the front lines of this virus again. Dr. Rich, thank you.
This transcript has been automatically generated and may not be 100% accurate.