Lianhe Zaobao:

The scientific community has yet to come to a definitive conclusion on the origin of SARS-CoV-2. There have been allegations that the virus may be man-made. What is the possibility of that? We also want to know if Chinese scientists are still tracing "patient zero" and if there is any progress? Lastly, the COVID-19 epidemic was first detected in Wuhan at the end of December 2019, and the Chinese authorities have taken very proactive anti-epidemic measures since Jan. 20, 2020. Looking back, could Chinese experts have done a better job, between the end of December and Jan. 20? Thanks.

Xi Yanchun:

We have invited Dr. Liu Peipei of the National Institute for Viral Disease Control and Prevention of China CDC. He will answer some questions related to virus research.

Liu Peipei:

Your first question is about whether SARS-CoV-2 is man-made, which is a hot topic of concern. In fact, as some of you may have noticed, there is a general consensus in the scientific community that the probability is very low. A Lancet paper co-signed by scientists from various countries illustrates this. In a word, the possibility that SARS-CoV-2 was engineered is extremely low. The most probable possibility is that the virus was transmitted from a natural host to an intermediate host and then to humans.

The second question is about the tracing of "patient zero", which many countries around the world are actively working on. Of course, we are also pressing ahead with this. Tracing "patient zero" is an arduous task, involving intricate data. In addition, as the epidemic lingers, a seropositive background is present in the population, but it is difficult to specify when people became infected.

Just as Director Wang mentioned, at the early stage of the epidemic, many people who were very likely asymptomatic have no medical records, which increases the difficulty of finding "patient zero". These two aspects have thus added to the difficulty. We hope scientists worldwide can press ahead with tracing "patient zero", and work together to fight the epidemic.

Xi Yanchun:

The last question remains unanswered. Experts sitting on the podium may add a few words to answer that question.

Jin Qi:

Just now, Professor Liu made a very good point that after every epidemic, the scientific and medical communities, as well as the people and society, will be concerned about one word, that is: "patient zero". It is a question that we can't evade in terms of epidemiological investigation. As Professor Liu said, it is a very difficult question for science to answer. For example, has the "patient zero" of the 1918 Spanish Flu ever been found? As for AIDS, "patient zero" contact with the disease was conjectured to have occurred in 1930, but later, new evidence emerged and the disease was suspected to have originated from a hunter in 1920 in a certain country. But that's just speculation.

One could say, this is the story from 100 years ago, and hasn't there been a breakthrough in science and technology since then? Let me give another example. In 2009, the H1N1 virus originated in the Americas and evolved into a worldwide pandemic. Has "patient zero" of the 2009 H1N1 pandemic ever been found? The answer is no. We can see that it is a really difficult task. The difficulty lies in the fact it requires a considerable amount of work and interdisciplinary collaboration.

I'll give you a hypothetical example to help you understand it. If "patient zero" was asymptomatic or had mild symptoms then he or she may not have seen a doctor at all. In that case, how could we identify him as "patient zero"? Even if we suspected he was the "patient zero" then he would be likely to deny it since there are no medical records to reference. Some may ask, will the serological epidemiologic investigation help as we have well-kept medical records. But if both A and B test positive for IGg, how can we determine which one contracted the virus earlier without additional information? We can't. The task is tricky. The medical and scientific circles are looking for an answer. Chinese scientists are also working on that. This is the first aspect. 

Second, as to what Chinese scientists did at the beginning of the outbreak, I can give you an example. My institute worked on the task of identifying the pathogen in the early days. For an infectious disease, that is the first priority in prevention and control. It is extremely important because only after finding the pathogen can we decide on treatment and other response measures. Since we got the samples on Jan. 2, our scientists slept for only three to four hours each day for a week. At an advanced age, I was burned out staying there. My colleagues did their utmost, and we identified the pathogen within a week. Was it fast? I think so. Thus, we can see from this example that Chinese scientists did play a big role in dealing with the outbreak at the early stage and made key contributions. 

Of course, if we are faced with similar problems in the future, we will be even more hardworking. And as science and technology advance, I believe it will take even less time to identify such a pathogen. This time it took us a week, but next time it might be only three or four days, or even less than that. 

Wang Guiqiang:

First of all, everybody pays a lot of attention to "patient zero", and that is certainly important for tracing the origin of the disease, containing the pandemic and preventing the next possible epidemic. But China is not the only country with a "patient zero" — each and every nation has its own "patient zero", and all of them need to be traced. This is important. 

Second, for any disease, people's understanding develops day by day. People say this new coronavirus is very cunning, and that's true. As we do more research on it, we find that it is different from other viral infections. Other infections may take one or two weeks to cure, and they are self-limited diseases. But this new coronavirus has a long clinical course, and that is obviously different from other coronaviruses. Also, the rate of asymptomatic cases is quite high, which indicates that the virus does indeed have a cunning side to it while interacting with our bodies. Etiology is an important part of the development of a disease, and so is the human body's reaction. If the immune system recovers, then the virus will be contained easily; if it does not, then one can remain infected for days, and the virus can be spreading for days on end. Thus, our understanding of the disease is a gradually developing process. Chinese experts did a great amount of work at the outbreak's early stages, and their research gradually progressed from etiology to epidemiology and clinical manifestation. Thank you.