[Mi Feng]

Dear media friends, good afternoon. Welcome to the press conference of the National Health Commission.

WHO convened the China part of the global SARS-CoV-2 origin tracing study hosted by Chinese experts. The origin tracing has been receiving high level of attention from the international community since we hosted a press conference on February 9, 2021 in Wuhan. Since then, the joint team of experts carried out intensive communication through video-conferencing, email and other means. After nearly two months' joint efforts, key consensuses have been reached, regarding methodologies, key findings, scientific hypothesis and next-step recommendations about this joint study of origins. In the afternoon of March, 30th, WHO hosted an information briefing for member countries and answered questions from the media. For today's press conference, we have invited the Chair of the Chinese expert panel, Mr. Liang Wannian, Mr. Feng Zijian, Head of the Group of the Epidemiology, Mr. Tong Yigang, Head of the Group of Animal and Environment, and Mr. Yang Yungui, Head of the Group of Molecular Biology. They will give us a briefing and answer questions from the media. We will have simultaneous interpretation and you can raise your questions in Chinese or English. First, let's invite Professor Liang to give us a briefing.

[Liang Wannian, Professor from Tsinghua University and Chair of the Chinese Expert Group]

Dear friends from the media, good afternoon. Yesterday, WHO officially released the COVID-19 origins joint-study report. And our international colleagues hosted a conference. All of us watched it attentively. Our international experts hosted a very excellent briefing by providing professional answers to many questions. It was an excellent session and we take pride in what they have done. Over the past several months, our Chinese and international experts as a joint team has been working extremely hard. Despite all the hard work, we believe it's worthwhile.

Throughout the process, we have maintained pleasant cooperation cordially. Today, I'm very glad to see so many friends from the media gathering here. So we have the opportunity to offer more information about some aspects of our joint study on COVID-19 origin. Since Feb, 9th, after finishing the China part of origins tracing, Chinese and international experts hosted a joint press conference in the city of Wuhan. Regarding the process and results of China part of study, as well as next-step recommendations for global origins tracing, a systematic briefing was provided. With the full volume of the report published today, it builds on the foundation of work in Wuhan while taking consideration of more sources of information from global study.

The key sections of the report are basically in keeping with the report provided on Feb, 9th, without principal difference except some grammatical polishing. It is a lengthy report, covering a lot of contents. The joint expert team consists of globally leading scientists. Based on scientific and prudent principles, we have been working very hard every day before the publishing of the report. A great deal of detailed description was provided covering epidemiology, molecular epidemiology, animals and environment as key aspects.

There has been a tremendous amount of data processing and analysis. For the next-step recommendations, they are given from the perspective of a joint global origins tracing with overall planning and careful contemplation. So the published report is the result of the efforts of experts. Here, we also want to thank our fellow international experts for their dedication. Please allow me to introduce the key findings of this joint origin tracing study and share some next-step recommendations.

About the key conclusions, coronaviruses with a high degree of similarity to the gene sequence of the SARS-CoV-2 have been found in bats and pangolins, but the similarity is not enough to make them the direct ancestor of the SARS-CoV-2. Animals, such as mink and cats are highly susceptible to SARS-CoV-2, suggesting that bats, pangolins or mustelids, felids and other species may be potential natural hosts. Through extensive early case surgery and process sample testing, it was found that in December 2019, a certain scale of transmission of SARS-CoV-2 occurred among Wuhan population. The earliest case detected so far appeared on December 8th, and the earliest case related to the Huanan Seafood Market appeared on December 12th. Most of the cases broke out in the second half of December. The Huanan Seafood Market is one of the outbreak points of COVID-19. But at the same time, the transmission may also occur in other places in Wuhan.

Environmental sampling and testing in the same time with the closure of the Huanan Seafood Market showed that the environment was generally polluted by SARS-CoV-2, especially the aquatic products stalls. It is suggested that the Huanan Seafood Market environment was generally polluted by the SARS-CoV-2, especially the aquatic and seafood product stalls. It is suggested that this market may have the possibility of introducing viruses through cold chain products, infected persons or contaminated animals or animal products. Large-scale testing of animal products in this market did not find positive samples. For cold chain products, we did not yet conduct relevant tests in the early 2020. SARS-CoV-2 was not found in bats in Hubei Province and a large number of livestock, poultry, and wild animals in various parts of China. No evidence of SARS-CoV-2 circulating in livestock, poultry, and wild animals was found before and after the outbreak. The joint expert group conducted a scientific assessment of the possibility of SARS-CoV-2 being introduced through cold/food chain, directly from the natural host, through the intermediate host, and laboratory, and the possibility of introduction was divided into five levels. The five levels are: extremely unlikely, unlikely, possible, likely and very likely, which is a five-level classification. The direct spillover of zoonotic diseases is regarded as a possible to likely and introduction through intermediate hosts is regarded as likely to very likely. So there is a range, especially for intermediate hosts range from likely to very likely. The channel of cold chain and food chain transmission is taken as possible while laboratory introduction is regarded as extremely unlikely.

The joint expert group has reached a consensus that these hypotheses are not geographically restricted from a scientific point of view. The expert team has been adhering to the concept of openness from the beginning, because the introduction of the virus from animals to people, and the outbreak of the Huanan Seafood Market may have taken a long time, or it may be a long-distance movement, including cross-border activities. So we need to have a broader vision, not limited to a certain place, but to focus on all parts of the world, and gather all kinds of information collected from various fields and channels around the world to help us better understand this virus and what happened before the outbreak in Wuhan, and trace the source.

Suggestions for further research in the next step: since we need to think from a broad perspective of joint tracing of many countries and places around the world, the WHO-China joint expert team are very serious and cautious in the recommendations for the future research. We have conducted many very long scientific discussions, and the main recommendations are as follows:

1. It is necessary to expand the globally unified database, including related databases of molecular, genetic sequence, clinical, epidemiology, animal monitoring, and environmental monitoring.

2. To continue to find possible early cases in a wider range of the world, we have already carried out related work in China, and we need to find more test materials in a wider range in the future.

3. Regarding animal reservoirs, scientists all over the world must work together to carry out related research in many countries and places, and to find more diverse animal species that are potential virus hosts.

4. We must further understand the role of cold chain and frozen food in this process.

The China part of the origin tracing report is concluded, but it is not the end of the origin tracing work as a whole. We all hope that this is only a step forward, and that in the future, under the leadership of the WHO, scientists from all over the world can unite and cooperate to continue to carry out the origin tracing of SARS-CoV-2 in a scientific way.

That's all for my briefing, thank you.

[Mi Feng]

Thank you, Mr. Liang Wannian. Now the floor is open to our media friends and please identify yourself before raising questions.

Question: [CMG]

We saw today that a joint report on virus origins between China and the World Health Organization has been released. May I ask Mr. Liang Wannian, as the main responsible person on behalf of China, how do you comment on this report? In addition, we would like to ask whether the conclusions of this report are consistent with our Chinese scientists' initial predictions and judgments of the epidemic? Thank you.

Answer: [Liang Wannian]

Thank you for your question. The origin tracing research report is the report of the China part of the global origins tracing study, because it is the global tracing report, this time it is only the China part of the report. This report can be said to be the result of devoted WHO and Chinese scientists. It is a joint research report based on science and facts. In the process of the WHO international expert group coming to China to trace the source, our Chinese and foreign experts have been adhering to the "four jointly" to carry out their work, which is to jointly formulate work plans, jointly carry out scientific research, jointly write research reports and jointly publish research results, these "four jointly" are principled of our joint team. It can be said that everyone is cooperating sincerely, and the dedication and input to this work is unforgettable.

This is an excellent international cooperative research. Since it has been over one year, many biological samples, products, and the environment may not remain in China and Wuhan especially. Because we did not understand this epidemic in the early days, let alone this virus, not all samples are kept. We tried our best to find them. I remember that at the press conference yesterday, an expert from Australia said it prettily that we must remember at the very early stage, people in Wuhan were operating in a system with out the information we have today. The issue of sample is a typical example.

On the other hand, it is a retrospective study, and there may be some differences or deviations in people's memories. At the same time, the methods and techniques we currently employ for origin tracing are not perfect, and they also have some limitations. Despite these problems, we still believe that this report is very valuable. It is helpful for further research in the future, including research on SARS-CoV-2, research on the epidemic or other emerging infectious diseases. This report also can withstand the test of history. As a joint expert group, we have been saying that we are confident about our report which is based on the available information and evidence, and it can withstand the test. Of course, we will continue to work hard, focusing on improving science and technology, and support the continued work.

In terms of communication and cooperation with WHO, our Chinese experts and foreign experts have assumed the attitude of seeking truth from facts, openness and transparency, because China is the first country to report the first case of the COVID-19, so China is the first to carry out the China part of global origin tracing research. As a Chinese scientist and a member of this joint expert group, we are able to participate in this work. It is our responsibility and we have a sense of mission. We should do this work well. Of course, origin tracing work is a continuous work, and the end of this Part does not mean the end of the entire origin tracing work.

In the next step, on the basis of the results of China's report, we will further carry out origin tracing in a variety of ways and channels around the world. At the same time, from the perspective of experts, we will continue to actively participate in WHO's origin tracing research under the global framework. Thank you.

Question: [Reuters]

Yesterday, WHO Director-General Tedros said that China did not provide the expert team with raw data in some areas. He also said that now we cannot rule out the possibility of the virus leaking from the laboratory, and we still need to investigate further. Why doesn't China provide raw data? Would you like to provide them now? Will China accept another team of experts to further investigate the possibility of laboratory leaks in China? Thank you.

Answer: [Liang Wannian]

First of all, it is said that China did not provide the original data. I don't believe the hypothesis or theory of this question is valid. Since our Chinese and foreign expert groups arrived in Wuhan, we have been making research plans and analyzing the research information and materials together. There is no difference between the information we have and that held by foreign experts, because upon receiving some of the information, different experts got their fair part and analyzed separately according to the division of tasks and then pulled them all together. The leaders of these three groups are all present, and experts from both China and foreign countries have been conducting highly integrated research. It's not that Chinese experts and foreign experts study in an isolated way. From the very beginning, we divided experts into three major areas according to their fields and specialties, and they worked together. So the assumption that we do not share does not stand. Of course, some data cannot be taken away or photographed according to Chinese law. But when we analyzed together in Wuhan, our database and information are open to everyone. For example, when it comes to patients' privacy, the sharing of some data must have the consent of patients. This is also a basic international rule. I think everyone can understand this.

Secondly, how do you define "raw data"? From a professional perspective, please allow me to comment on the nature and concept of data. There are sorts of data. Even the basic data might be complex, related to a variety of terms. On that basis, the data are organized for the analysis and then categorized based on gender or age groups. Those are already processed data. They may not be qualified for analysis yet, requiring further digging and integration which change data into information. In this process, we start from the original data to data for the purpose of analysis to the formation of a database. It takes some time and heavy workload. It’s beyond your imagination that our experts, once arriving at the site, read through every case and every animal sample covering the original records. That’s unrealistic and unnecessary scientifically. We must set it straight. Then what are original data? With a pile of hundreds of thousands of documents on the table, where shall our experts start? We must establish a database for practical analysis. And our Chinese experts approached the same data as foreign experts.

Regarding the question raised by Dr. Tedros, I am not sure how he understands this issue, because it is a matter for scientists, and whether the research report that our scientists draws on the basis of the data shared by everyone is complete or not is up to scientists and history. Regarding the next step of tracing, I said that this is a global tracing. We only did the Chinese part, so it must be continued, especially from a broader perspective. However, Chinese scientists are also particularly willing to cooperate with scientists from all over the world, handling the issue of origin tracing scientifically, thus truly finding the source of the virus through harnessing science and technologies. I think that everyone will work hard and we will definitely be able to reach our goal. Where does it go and how to do it? There are some clear or relatively clear opinions in the research recommendations. How to turn these opinions into actions? It is necessary to make the plan concrete. In terms of time, place, and methods, some concrete plans may be proposed. I think that now I can only say from the perspective of this origin tracing report, it needs to be continued. So how to do it specifically? We must make a specific plan under the framework of our opinions. Thank you.

Question: [Yonhap News Agency]

As to the joint report of COVID-19 origins, 14 countries published a joint statement, explaining their worries about the postponement of the report release and the overthrow of complete data. What is the position of China?

Answer: [Liang Wannian]

About that matter, firstly, on Feb, 9th, we convened a press in Wuhan, introducing the background, findings and recommendations of the report jointly. But those were consensuses we reached at that moment which formulated a framework of conclusions. Due to the tight schedule, we spent 28 days in Wuhan and compiled the report afterwards. It took some further time. Our experts had to carefully review and organize every sentence and every conclusion and all data. We also had to do some presumptions logically in paragraphs. Whether the conclusions are justified is decided by science. After all, this is a research report by scientists. Evidence is the basis for us to refer to. Meanwhile, our scientists returned back to their motherland on Feb, 10th since when there have been time difference in their communication. It's more inconvenient than doing the job in the same place. Otherwise, we could have met anytime. But in fact, we had to negotiate a perfect timing for the conference. Some are in the afternoon while others are in the evening or early morning and midnight. This report is in both Chinese and English. And both languages must be translated simultaneously. Once the Chinese version is ready, our foreign experts are also waiting to read it. But we have to make sure that the two versions are consistent. So there's more work about it. I also know that after this report is published, the whole world is paying attention. It is not only our professionals who are paying attention. Our public, our media, and even ordinary people will study our report from different angles. Therefore, the overall framework of the report, the logical relationship and scientific nature of each sentence in the report must be ensured. So it is done well to the best of our ability. Because of that, I don't think our experts would agree with the issue of postponement. At that time, we always had a principle of quality first, time must be secondary to quality, and only when the joint expert group of China and foreign countries approved it can this report be released. So we didn't have a deadline. Of course, we also know that the whole world is paying attention. We are working hard day and night. I want to make it clear. Therefore, it is not because of some interference, nor the laziness of scientists, nor is it because of other reasons that delayed the publication of this report. We are ensuring the quality, making it more scientific and complete. I want to explain this to you.

Regarding the issue of data integrity, I am going to repeat something. In any research, no one dares to say that the information he collects and holds are 100% perfect, complete, and impeccable. For an emerging infectious disease, as scientists, we have a basic idea from the beginning. At the first video conference, we said that we might end up with this report and that it is always yet to be improved because science is advancing, people's understanding of this virus and disease is deepening, and our technology is also evolving. Therefore, we can only work hard to make scientific judgments, conclusions and reasoning from the information we have. That's our mindset. What are complete data? This is another scientific question, how many data make them complete? We may have to collect all the data without solving a scientific problem. How to acquire all data? Therefore, for the completeness of the data, it may be difficult to scientifically identify how much data and what type of data collection is considered as complete.

Of course, as a joint research team, when we first arrived in Wuhan, including the visit in July, I clearly remember that two experts came from the advance team of WHO. Our Chinese experts worked with them for a few weeks. A special outline has been made for research on the China part of the global study of origins of SARS-CoV-2. It's called TOR. In fact, one of the most important questions is, from what dimension and range do we collect data? These data cover animals. In terms of early cases, inspection and testing, and even some related chains, what data should be collected? Where are data from? What kind of data are them like? What is the method of obtaining these data? In fact, we have done a very in-depth research.

We also clearly remember that in the first 14 days after the foreign experts arrived in Wuhan, they were in isolation according to relevant Chinese laws and regulations. I remember that in our first week, it took us five to six days to come up with a research plan. This research plan includes what we do every day. And for a majority of time, we were discussing our goals. How do I get data? What kind of data shall I get? In fact, when I look back and think about it now, I have always believed that from the current level of knowledge and conditions, we were trying to collect everything we could.

Of course, it must be admitted that it can never be said that 100% of the data have been collected. I want to clarify. Our entire conclusions are based on the available data and the knowledge and experience of scientists added by reasoning and inferences. It's not that the rhetoric of the report being incomplete can make it unreliable. In medical and public health researches, there is a method called sampling survey. In fact, it is often more effective than census to some extent. From this perspective, the so-called data integrity must have boundaries. That's my explanation, thank you.

Question: [Kyodo News]

I have two questions. First, regarding the content of the joint statement just asked by a Korean reporter, my understanding is that the issue of postponement does not refer to the publication. Instead, it may be due to the late on-site inspections in Wuhan which came after more than a year since the outbreak, resulting in the postponed release. What's the take of China on this? Second, Professor just answered the Reuters reporter, but I still want to ask again. The report said that more in-depth data analysis or origin tracing is needed, such as tracing breeding animals in China, etc. In the future, will China accept another study similar to this cooperation? Is there such a possibility?

Answer: [Liang Wannian]

Alright. Two questions. For the first one. Your concern is about the late visit of WHO experts to China. Although China was the first country to report the COVID-19 cases, globally speaking, China was also the first country to conduct joint study of origin tracing with WHO. It's rather hard to measure the time point. Actually, the Chinese scientists kicked off origin tracing study in the early days of the epidemic. I remember that together with Professor Feng Zijian and other scientists, we were fighting against the epidemic for one thing and conducting origin tracing study with our expertise for another. For example, we gathered samples of animals, environment and specimen since that early in Huanan Seafood Market. China accumulated experience in responding to such widespread epidemic and infectious diseases. So we have been doing this before the establishment of international experts. The establishment of a joint team needs a process. I don't think one year later is late. There are factors behind their coming or not. As a scientist, as long as we scientists carry out this task on the basis of science, it's never late. Instead, I think the fact that China was the first to carry out the global origin tracing study is a manifestation of the Chinese government's attitude. As a scientist, it's totally acceptable. One more word, the Chinese scientists will continue this origin tracing work based on our knowledge, capabilities and methodologies. We will do this until we find the origin.

The second question is whether the so-called next step is to conduct further analysis of China's data, including some analysis of factors in the transmission chain, analysis of animals, and as you just raised it, can WHO experts come for a second and third time. I think that I have answered this question in principle just now. The analysis must be done. Chinese scientists are willing to work with scientists around the world to find the source of the virus. As long as the goal is not reached, my generation and the generations to come will definitely reach it one day. However, from the very beginning, we said that the problem of origin tracing is a very complex and systemic problem, and it is absolutely impossible to solve it overnight. Look at our history of infectious diseases, especially the history of new infectious diseases. We have a basic understanding so far. It will take a long time to truly find its source and be recognized by the world. Many of our diseases have been prevalent for many years, and so far we have not found the source. Of course, the failure to find the source does not prevent us from intervening and controlling it. This is still ongoing. Therefore, we must definitely do it. Even if the World Health Organization says that global origin tracing is abandoned, our Chinese scientists will still work hard to continue this work.

Origin tracing study will certainly involve data analysis. Tracing origins is about finding possible transmission pathways of animals, natural hosts and intermediate hosts. By monitoring and processing data and specimen, we will adopt a methodology. Whether experts will come for a second and third time will be decided by actual conditions. It is a misunderstanding about traceability that only the Chinese part is tracing origins. Now that the source is unknown, one of the four possible pathways is the cold chain. Scientists agree that although Wuhan was the first place to report cases, it doesn't mean that the epidemic emerged firstly in Wuhan. From that point of view, we must adopt a wider view of tracing origins. In the next step, we must identify priorities. In the research recommendations in the report, there are three areas to be prioritized. Chinese scientists will refer to these recommendations and proceed together with international experts under the leadership of WHO. So I can't answer your second question now. It will only be decided by conditions, such as the progress of global tracing activities and rising demand in certain circumstances which will determine whether, when and how they may come again. Thank you.

Question: [Phenix TV]

Recently, we have seen reports from some foreign media. Some foreign experts said that the source of the new coronavirus is the same as the source of the SARS epidemic in 2002. It is likely to come from the market in China. In particular, some foreign experts believe that the virus may originate from southern China. The reason is that in February last year, the wildlife markets in the south were closed one after another. How do the experts think about this statement?

Answer: [Tong Yigang]

At the beginning of the outbreak of COVID-19, the world's knowledge of SARS-CoV-2 was very limited. Based on the knowledge of the cross-species transmission of SARS-CoV-2, it's also speculated that it may have a certain relationship with wild animals and some farmed wild animals. Worrying about the deterioration of the virus, the Chinese government has taken active measures in all aspects in order to control the spread of the epidemic as soon as possible, including extensive restrictions on the movement of people and the complete closure of animal farms. As the global pandemic continues to spread, more and more evidences have also shown that these measures taken by the Chinese government in the early stages of the epidemic are very effective, slowing down the spread and mutation of the virus, and making contributions to human health and protecting the health of the Chinese people.

Regarding the animals, I want to emphasize that the animal samples we tested from the market were not positive. I also thank the Ministry of Agriculture and the State Forestry, Forestry and Grass Administration. They have done a lot of work from 2018 to 2020. During the period, more than 38,000 samples of livestock and poultry and more than 41,000 samples of wild animals were collected in 31 provinces, municipalities, and autonomous regions in China. These samples were tested, and no positive results were detected. Before and after the outbreak of the Covid-19 in China, there was no evidence of the virus spreading among poultry, livestock and wild animals. For the upstream supply chain of the Huanan Seafood Market, we have actually conducted a comprehensive investigation, which involved more than 20 countries and regions. If a thorough investigation is required, the WHO will lead and coordinate the efforts among countries to deepen the work of virus tracing in the next stage.

For some southern animals such as bats, Chinese scientists have done in-depth research. Some very similar viruses were found in southern China, but no SARS-CoV-2 was found. In addition to bats, many other animals are susceptible, and there is also a lot of evidence. So far, we have not found conclusive scientific evidence to support the hypothesis that there is a chain of virus transmission in southern China. The scientific consensus formed by both Chinese and WHO experts through serious discussions has been released at a press conference on the 29th and will also be reflected in the joint origin tracing report. Regarding the hypothesis that the virus is transmitted to humans through animals, the joint expert group of China and the WHO has reached a consensus based on the current scientific understanding of the coronavirus. It is believed that the transmission from animals to humans is likely, but this does not mean the joint expert group found any new evidence that can prove the existence of such transmission chain. Virus tracing, especially through an intermediate host, is a very difficult scientific issue, and we need a scientific attitude towards it.

In the next stage, we need a broader perspective. Under a global framework, we will conduct comprehensive and detailed investigations over a variety of animals. It goes against science to embrace a limited mindset and may even lead us to wrong directions, so virus tracing requires the joint efforts of scientists all across the globe. Thank you.

Question：[CGTN]

The joint research report mentioned the experts' suggestions for tasks in the next stage, including continuing to search for possible early cases in a wider range of the world, and searching for potentially host animals in many countries. We have also seen some reports of Covid cases from other countries earlier than Wuhan. What is the focus of the virus tracing effort going forward? Will it go to other countries or regions for origin tracing research? How long will it take to eventually find the source?

Answer: [Feng Zijian]

Thank you for your question. Oftentimes, the first place of an outbreak is not necessarily the origin place of the virus. In the past, viruses caused epidemics of major diseases, and its origin tracing work was often a cross-border and cross-regional cooperative research. Everyone may has read some reports, which said some cases with suspected positive testing result with SARS CoV-2 have been found in other places before the Wuhan outbreak, and further cooperative researches are needed to verify these reports. These clues are also very important in determining the time and location of animal-to-human transmission and ultimately find the natural animal host. These tasks are worthy of our further work. As Team Leader Liang mentioned just now, our joint expert group also offered some suggestions, which actually are to strengthen multi-country cooperation in a global perspective to further promote the origin tracing studies. Thank you.

Question: [Xinhua News Agency]

Could you share with us more about molecular tracing in this origin tracing work. Also, a variety of mutated strains of the coronavirus have recently appeared. How do you view this phenomenon from a professional point of view? Thank you.

Answer: [Yang Yungui]

Thank you for your question. I am responsible for molecular tracing, which is mainly carried out around the following aspects. First, systematically sort out the genome sequence of early cases in Wuhan. Second, systematically collect and sort out the global early cases and the distribution among countries, as well as systematically collect and sort out the known genome sequences of different variants, and construct the most critical genome sequence and information database for molecular origin tracing. Through our cooperation with the WHO molecular team, we have made the following progress.

First, we have established a global database for SARS-CoV-2 information, and integrated genome and epidemiological and clinical data, which helped to carry out the molecular tracing research.

Second, through integrated analysis of molecular data and epidemiological data, we studied the correlations and pattern of these variants and exposure factors, thus providing a very important reference for our research direction. There is also a systematic evolution analysis based on the early virus sequence, and calculations of the time when its earliest common ancestor appeared, thus studying the characteristics and pattern of the transmission and evolution of the early virus, and understanding the early outbreak in Wuhan.

Another very important piece of work, as mentioned earlier, is to fully integrate the information on early COVID-19 cases, environmental samples, or early samples that have been made public around the world. In particular, as mentioned earlier, we have sorted out the early cases and the sequencing of the virus in countries outside China. The joint expert group reached an agreement and put forward four recommendations under the global framework:

First, establish an integrated database covering all COVID-19 genomes in the world. The WHO will coordinate works related to genome sequencing, epidemic studies, metagenomics, and environmental studies.

Second, going back to the question on original data, it is precisely because we analyzed the original genome sequencing of early cases in China, we were able to put forward a very important guideline for the next stage of the global tracing work. We hope to offer our proposals regarding the depth of sequencing and building of sequencing platforms.

Third, by sorting out available information and materials, the expert group agreed upon the existence of overseas samples earlier than Wuhan, and proposed to continue tracing the early samples on a global scale.

In addition, it is proposed to expand the screening of species on a global scale, which is included in the published report.

There is another issue that reporters are very concerned about. We are also concerned with the fact that a variety of variants of SARS-CoV-2 have been identified. However, all the experts know that SARS-CoV-2 is an RNA virus, and that mutations are quite normal along the evolution journey of such virus, which also shows that the virus is adapting to humans and the environment with the passage of time. So, what does this tell us? It shows how challenging and arduous the fight between human and virus is, and that global cooperation is needed to trace the origin of the virus.

Finally, I'd like to take this opportunity to thank the joint expert group and the whole team, especially our partners from the epidemiology group and environmental/animal group, because the molecular group that I'm leading needs the data from these groups. I would also like to thank the providers of sequencing information, especially China's CDC, and the staff of China National Center for Bioinformatics, who provided a very important support for our molecular origin tracing group.

Question: [Hong Kong China Review Agency]

Since the outbreak of the epidemic, what kind of communication and cooperation has China and the international community made on tracing the source of the virus? What research has been carried out? And how has China contributed to this global endeavor of virus tracing?

Answer: [Liang Wannian]

Let me answer this question. Since the outbreak of the epidemic, China has followed relevant international laws, especially the requirements of the International Health Regulations, to notify the World Health Organization and relevant countries of the epidemic in a timely manner. Some major discoveries of the Chinese scientists were introduced to the world via academic papers using the language of science. As I've learned, we were formulating some diagnosis and treatment plans, epidemiological plans and some related treatments from the very beginning. Some technical specifications, guidelines, etc., including epidemiological surveys and monitoring, were communicated and shared in various forms in a timely manner. Therefore, from the perspective of an expert and a scientist, China's handling of the outbreak met the requirements of international law as well as laws in China. Second, the communication and disclosure of information was speedy and timely, and was done in accordance with relevant regulations. Third, because it was a new virus and the common enemy of all mankind, it is necessary to gather experts in various fields for a collaborative study, whether it is etiology, epidemiology, clinical science, or surveying and testing, global cooperation is needed among all scientists. And China held an open and cooperative attitude from the beginning.

I clearly remember that during the most difficult time of the epidemic in China, our scientists, including our clinicians and public health doctors, were fighting the epidemic on the one hand, and working with international experts, and international colleagues on the other in conducting multilateral exchanges. When China had basically contained the epidemic within its borders, we were willing to set up this platform to introduce our experience, practices, and even lessons to the world. I think this is something that makes me feel particularly proud. I feel this kind of communication, cooperation and exchange is a magic weapon for us to jointly overcome this disease.

In addition, Chinese scientists in different fields actively performed their responsibilities, from research to exchanges, they have engaged in basic research, clinical research, or epidemiological and public health research. We all felt the same way, because this is truly what we did throughout this period of time.

[Mi Feng]

Thank you. Regarding what the Chinese government has done, I would like to add one more thing. The visit by WHO experts to China took place in this spring, which is the most critical period for pandemic prevention and control. To support their work, we and local governments have always adhered to the principle of openness, transparency and cooperation. We tried our best to coordinate relevant activities, and fully met the requirements of WHO international experts. It can be said that the WHO experts went to all the placed they wanted to go, including Jinyintan Hospital, the Huanan Seafood Market, the Wuhan Institute of Virology etc. They also met all the people they wanted to meet. For example, some medical personnel, laboratory personnel, scientific research personnel, and market managers, as well as some merchants, and volunteers at the time, recovered patients, and some family members who lost their loved ones, etc.

We carried out extensive efforts to ensure a successfully, efficient visit. We did our best to provide services and supports. There are thousands of people engaged in related work in front and behind the scenes. On the February 9th meeting, Team Leader Pete expressed his gratitude to these thousands of volunteers. Wuhan is a heroic city, and there are always touching stories here. The successful release of this joint research report is inseparable from the efforts of all the staff.

Question: [Hong Kong Economic Herald]

Thanks you and I'm from Hong Kong, I have a question for Professional Liang. We have not confirmed the origin.

What is the most challenging point in the past few months? Have we confirmed the origin of other viruses?

Answer: [Liang Wannian]

With regard to origin tracing, it's is a vastly complex scientific project.

In the history of emerging infectious diseases, So far we do not have a precedent of successful origin tracing, With one study alone, we are not able to answer all the questions, but we are confident in saying that with each phase of the study and each report released, we are one step closer to the ultimate truth of its origin.

So the difficulty of origin tracing lies in the fact that the virus is very cunning. So it's very difficult to observe the pattern of an accidental spillover. The outbreak could be triggered in a very accidental way. So how could we identify the carrier of the virus? It's like searching a needle in the ocean.

And for SARS-CoV-2, If it is stable, it is easily identifiable, like high fever, it could be less difficult to trace its origin. But for SARS-CoV-2 tracing, back in February on the 24th, actually a joint WHO Press Conference was held in Beijing, everybody was struggling to find the right word to describe this virus. Then people started to come to terms with its uniqueness. It's a very cunning virus, prone to mutations. It also has very extensive symptoms, ranging from highest severity or even mortality to asymptomatic. At that time, we didn't have knowledge about asymptomatic infection of the virus. but today, most of the infections are asymptomatic cases. That's why it's very difficult to trace the origin of the virus.

For the first reported case in Wuhan, according to current research, the case identified on the 8th of December was the first case. But it's by no means equated with the indexed Case Zero. So we are looking at the first zoonotic transmission or spillover, but for mild and asymptomatic cases, it's almost impossible to identify them in the first place, that's why it's very challenging. Moreover, if we want to trace its origin from animals like bats, pangolin and other species, they could all potentially serve as hosts.

From a professional point of view, there are two types of them: natural hosts and intermediate hosts. For a host to become the source of infection, it's another process. Some animals are reservoirs, but they do not infect other animals. But there are animals who are both hosts and reservoirs, and they can also serve as an amplifier of the virus, and they will release the virus into the outside environment. Then those animals could become sources of infection, so we need to make a distinction between these two types of animals. We are tracing the virus in animals such as bats, but even when we identify the virus from bats, that does not mean the animal is the host. There is the possibility that there's another species in the upstream, and that maybe the most original host.

So with respect to bats or pangolins, they are captured sporadically and accidentally, and then we sampled and tested them. But if the samples carried only a limited amount of virus, it was difficult to identify such virus. There are lots of issues with respect to possibilities, but we have to engage in this endeavor. We have to follow a science-based approach to study all these possibilities and scenarios. It's challenging and difficult, but it's our duty as scientists. Thank you.

Question: [China Media Group]

We know that this joint study was jointly carried out by an international team of experts selected by the World Health Organization and Chinese scientists. We would like to ask, how did our two parties carry out the division of labor and cooperation? In addition, if there is a collision of views during the exchange, how will the two sides deal with it? Thank you.

Answer: [Liang Wannian]

This question is very good. In fact, we started out as an international team, with Chinese experts and WHO experts. I remembered that the foreign team leader, Dr. Peter and I said that we are a family with more than 30 members, and we have a very important task together, that is, we have to raise a child, and that child is the final research report. So we must do it with a family atmosphere and attitude.

Regarding the specific working methods, the "four Jointly" is our principle, that is, we must be work closely together. We all shoulder the same mission. We are all scientists with the shared task of virus tracing. On the basis of the "Four Jointly", our working method is to break the boundaries between countries. We divided the origin tracing work into three major areas: one is the field of epidemiology, the Chinese team leader is Professor Feng Zijian, and the foreign team leader is Professor Fisher from Denmark. Under the leadership of the two, experts in the relevant epidemiological field entered this group, and everyone worked together. The Chinese team leader of the molecular origin tracing group is Professor Yang Yungui, and the foreign team leader is Professor Marion from the Netherlands, each leading his own team. Regarding the animal and molecular origin tracing group, the Chinese team leader is Professor Tong Yigang, and the foreign team leader is Dr. Daszak from the United States. Therefore, we started by integrating experts into a team according to the research field.

In terms of specific working methods, we could only work through video conferences in the first 14 days, of course, mostly meetings within the team. Dr. Pete and I are responsible for major issues, directions, methods, principles, and coordination between various teams. The specific details and implementation are the responsibility of the team leader in each field. Everyone worked very happily and very efficiently.

Of course, there were conflicts in this process, because even if scientists are from the same field, there are three groups of scientists from different countries, even if they are from the same country, they are from different backgrounds and have different perspectives. Virus origin tracing must be conducted in a multi-disciplinary and multi-faceted approach. For every method, information, and strategy, we certainly have arguments, and sometimes this argument could be fierce, but we feel it's very normal. We'd ran into serious problems if we didn't argue, because the process of pursuing the truth and approaching the facts is a difficult scientific process. Only through arguing can a consensus be formed.

I have read some reports saying that there are some fierce disputes between Chinese experts and foreign experts, which is true. Chinese experts also debated fiercely within their separate teams, and disputes between different groups were also fierce. This is only normal. The purpose of the argument is to make the origin tracing more scientific and the evidence more complete. I want to emphasize this point in particular.

I remember the last big group meeting, when we spent the whole night reading every line of the report, and finally reached a consensus. At dawn, we finally stopped all the arguments, we all sat down together and saw what our child was like. The child is at least a normal child, a child who can stand the test. So we are very happy. After the report came out, we, as scientists, both Chinese and foreign experts, have two most important feelings. One is pride, because we have produced this report through our hard work. This report is valuable, whether it is for the control of the pandemic or for the future research. The second feeling is self-confidence. As scientists, we draw conclusions based on existing data and information. The report is based on science and evidence. Thank you.

Question: [China News Agency]

Just now we mentioned the issue of virus hosts. In the joint report, it's indicated that transmission through intermediate hosts is "possible to likely". Then, regarding the issue of transmission, what consensus have Chinese and foreign experts reached? Thank you.

Answer: [Tong Yigang]

Thank you for your question. Although the animal host or potential host of the virus is not yet clear to us, the virus may have a direct spillover from its natural host to humans, or just like the SARS virus, where there may be an intermediate host. Regarding the tracing of animal hosts, after the outbreak, the Ministry of Agriculture the State Forestry and Grass Administration conducted antibody and nucleic acid tests on tens of thousands of samples collected in 31 provinces, municipalities and autonomous regions in the country, and none of them tested positive. This also shows that China did not find evidence of the spread of the virus in poultry, livestock and wild animals before and after the outbreak.

At present, there is scientific evidence that the genome sequence similarity between the coronavirus RaTG13 collected in bats in Yunnan in 2013 and SARS-CoV-2 reached 96.2%. The bat coronavirus RmYN02 collected in Yunnan Province in 2019 is 93.3% similar to SARS-CoV-2. In addition, there are bat coronaviruses ZXC21 and ZC45 collected in Zhoushan, Zhejiang in 2015 and 2017 reaching a similarity level of 87%. Recently, different coronaviruses have also been detected in bats in Japan, Cambodia, Thailand and other countries, featuring higher or lower levels of similarities, but so far they have not exceeded 96%. In addition, there are reports showing that pangolins smuggled in from abroad intercepted by Guangxi Customs in 2017 carried a coronavirus, which is 88.5% similar to SARS-CoV-2. In 2019, a type of coronavirus was also found in pangolins smuggled from overseas intercepted by Guangdong Customs, which is about 90% similar to SARS-CoV-2.

Based on some of the above research results, although the specific host of the virus has not yet been found, bats and pangolins are the most likely hosts. The joint expert group has reached a consensus and we believe that these assumptions are not geographically restricted from a scientific point of view. Experts have been adhering to an open concept from the beginning, and believe that the introduction of viruses, the spread of viruses from animals to people, and the spread to the Huanan Seafood Market and the outbreak of the epidemic may have gone through a long time, or there may have been some long-distance movements, including some cross-border movements.

We also know that bats are flying animals, and their caves are found in many rural areas, and bats are social animals, and there is a high probability of cross-spreading between each other. Most of the similar viruses on bats were found in China's Yunnan region, which borders some countries in Southeast Asia. In addition, as mentioned earlier, such viruses have also been found in Southeast Asian countries. Therefore, we feel that follow-up research under the global tracing framework is very necessary. Similarly, pangolins are distributed in Southeast Asia. The sources of the two coronavirus samples we have discovered are also pangolins that have entered from overseas. Therefore, there is also such a possibility that pangolins in Southeast Asia were carrying a similar coronavirus, thus it is necessary to conduct further research under the global framework. Therefore, we hope that in the future, under the leadership of the WHO, scientists from all over the world can unite and collaborate to carry forward this work in a scientific way. Thank you.

Question: [China Daily]

We have read reports from foreign media that some countries said that the three staff of Wuhan Virus Institute became ill in early and mid-November 2019, and the symptoms were similar to Covid-19 and influenza. They believed that that this may be the origin of Covid. What do the experts think? Thank you.

Answer: [Tong Yigang]

Thank you for your question. Regarding this issue, the Chinese expert team conducted an investigation and debunked the rumor. The Chinese expert group reviewed some meeting records of the WHO-China Joint Expert Group's visit to the Wuhan Institute of Virology on February 3, 2021, and restored the whole facts:

A researcher from Wuhan Institute of Virology reported the Institute's participation in the influenza surveillance system in cooperation with hospitals mentioned by foreign members of the WHO expert group. At that time, he clearly responded to foreign experts regarding what happened in the beginning of 2019. The Wuhan Institute of Virology and a hospital in Wuhan collaborated on a research on influenza epidemic monitoring. This research involved sample collection from January 2019 to January 2020. A total of 1,001 samples were collected. These samples were collected in 2020. The Wuhan Institute of Virology carried out the testing in March of 2020. Because they have the testing capabilities in this area, they conducted a retrospective screening of these samples and found that in January 2020, there were 700 samples. The samples are from the period of January 2019 to January 2020. Among the 700 samples there were 4 positive nucleic acid cases found, that is, 4 influenza virus and SARS-CoV-2 co-infection cases were found from January 2020. Among the 4 co-infection cases, 3 were adults and 1 was an elderly person. They were patients from the cooperative hospital, not employees of the Wuhan Institute of Virology. In this case, their article has been published a long time ago. If you are interested, you can further study the detailed description in their article. Thank you.

Question: [Spanish EFE]

Dr. Tedros said that China is willing to receive more WHO delegations in the future. I would like to ask if there is such a possibility in the near future for more experts visits from the WHO.

Answer: [Liang Wannian]

A friend in the media asked me this question just now. I look at this issue from the perspective of a Chinese scientist. The origin tracing work is still in progress, and it is carried out under the global framework. Chinese scientists, like the Chinese government, are willing to contribute to global origin tracing. I think this is a very clear-cut position that we hold.

The second point, as for whether/when and how the next visit is organized, it's determined based on the relevant suggestions put forward in our research report, and it also hinges upon the progress of the tracing effort. It might be a bit early to talk about the next visit because after all, this report has just come out.

Third, right now our focus is to understand the most possible introduction channels, we have proposed four possible channels, and each has some supporting evidence and opposition evidence. If some similar work has already been done, but there is only a difference in quantity in other countries and regions, then this is only a qualitative difference. When scientists are making the next research plan, they may have to prioritize, should we constantly expand the scope or make some qualitatively changes, and this is yet to be determined, and scientific research has some basic principles to follow. So this is how I think about this question, thank you.

Question: [Health News]

This question is directed to Team Leader Liang Wannian. We all know that the origin tracing process is very long, and during this process some of the experts involved have been questioned from the outside and also face pressures from public opinion. Some media say that China has put some pressure on WHO expert. What is your take on this?

Answer: [Liang Wannian]

Thank you for your question. I have also seen this statement of some media. After I read it, I have a general feeling that this statement is not in accordance with the facts. The joint expert group, whether it is a foreign expert or a Chinese expert, feels no such pressure. Even after we left Wuhan, we were communicating via video conferences. And even in our private conversations we were saying there was no pressure from the outside, especially from the China side. We did not feel this way, so this is just a groundless accusation.

The second point is that after the foreign experts went back, they also received some interviews, and spoke on different channels to introduce the process and results of our research. I have not found that they have been disturbed. Meanwhile, they also responded by saying that these accusations were not reflecting the realities of their visit to China.

The third point, I feel very strongly about what the moderator said just now regarding how the Chinese side has contributed to this global tracing effort. Our experts went to all the places they wanted to go, met all the people they wanted to meet, read all the materials they wanted to read, and sometimes we discussed till very late at night, if we think we need to see some person or access certain material, we would tell the liaison person and even the government immediately. They had to make arrangement for us as soon as possible, oftentimes we gave them surprise visits. As we emphasized in our joint report, we are very grateful to the local government for providing us with a lot of convenience. I watched a WHO press conference last night, and they also specifically mentioned this point. Without their cooperation and support, we must go alone with our Chinese scientists. There is no way that the tracing can be done in such way. So in general, we conducted our work in a relaxed environment. Of course we were under some pressure. As a Chinese team leader, I was under pressure because I have seen a lot of reports, it is stressful for me and our experts. As I said earlier, Chinese and foreign experts say that we are confident, because we are scientists, we used scientific methods, and it has nothing to do with politics. Thank you.

[Mi Feng]

Thank you to all the experts, for briefing their efforts in this press conference, and we also take this opportunity to thank Chinese and foreign experts for their outstanding contributions to this joint origin tracing study. This concludes today's press conference, thank you all!