The second important thing about obtaining our own virus sample is that it enables scientists to study the disease itself, methods to test for it and vaccines.

We heard that scientists would be able to develop vaccines within three to four months after obtaining a virus sample. Is this true?

A candidate virus for vaccine development is different from a virus sample taken from a random patient. Developing these viruses so that vaccine makers can use them is very complicated. The candidate A/H1N1 viruses for vaccine development are being developed in the labs of other countries. The United States has been developing a candidate virus after it obtained a virus sample in April. I believe Chinese vaccine makers would also be able to obtain it and start producing their own vaccines. For the time being, we do not have a plan to develop a candidate virus for vaccine development.

This first virus sample was taken from a patient from Sichuan Province. I learned that your center is also trying to extract viruses from confirmed patients in Shandong Province and Beijing. Why are you collecting new samples?

This is a good question. Our biggest concern now is that this virus might mutate. How do we learn about virus mutation? We have to keep obtaining virus samples and testing their genetic sequences. Only these procedures can guarantee that the virus has not yet mutated. Just as I told you before, we tested our virus sample and found it similar with samples obtained in the United States and Canada. We can say they are the same virus or the same type of virus. The virus has not mutated after spreading to China. But we cannot say for sure that it won't mutate after entering China. Therefore, we have to continue our work of virus separation and testing.

How would this virus mutate?

In theory there are two possibilities. One is that this virus mixes with other existing flu viruses and creates a new hybrid organism. The other possibility is that its accumulative changes through spreading among people will change its properties. The problem is how all flu viruses mutate. We still don't know which mutation path the A/H1N1 virus will take. Scientists around the world agree that every country should monitor the virus, just as I said, through extracting and isolating it, testing its genetic sequence and analyzing its biological characteristics.

We have learned that Japan has diagnosed several non-imported A/H1N1 cases. Can people interfere with the process when the disease changes from imported dissemination to non-imported dissemination?

Yes, they can. Our interference is to postpone non-imported dissemination. We can learn from Japan's experience. A/H1N1 spread to Japan through four imported cases in the beginning. It was only yesterday that we saw the news that they had found non-imported cases, a while after their first A/H1N1 case. Japan did not immediately see its second- or third-tier cases after the first four imported cases, as many people expected. In other words, the measures taken by their authorities did put off the process.

Do you mean we are going to see a steady increase of non-imported cases?

Theoretically, yes. Now we all know this virus' characteristics. What distinguishes it from other influenza viruses is that people with no symptoms or very mild symptoms can also be contagious. These people cannot be located by our monitoring system, which makes our work of discovering patients in a timely manner and quarantining them challenging. Under such circumstances, we might start to see second- or third-tier cases.

To control imported cases, we only have to set up diagnostic points at all our ports. After non-imported cases appear, how can we readjust our monitoring network?

We need to take measures with different focuses at different stages of disease prevention. When a country only has imported cases, it focuses on preventing imported-cases from entering its territory and spotting the infected after they arrive. It involves inspection and quarantine authorities, which are expected to quarantine the patients and put those who came in close contact with him or her under medical observation. But when the infection reaches the stage currently being seen in the United States, it becomes impossible to contain it by merely quarantining individuals. The focus at this point will be shifted to monitor the virus for mutation and drug resistance, which will be realized through a monitoring network rather than observation on individual cases. Thus the priority will switch from spotting individual cases to using the monitoring network to discover virus mutation in a timely way.

As we have noticed, the body temperature test does have problems. We need more measures. I learned from the news today our inspection and quarantine authorities are asking people coming back from abroad to register their travel schedules as well as their contact information and to report to authorities if they develop symptoms. These could be remedial measures if a patient was not discovered on the spot.