SARS SPECIAL REPORT KM May 17, 2003

Following WHO international meeting of epidemiologists studying SARS. The meeting took place in Geneva.

Mr Dick Thompson: OK, this is Dick Thompson at the World Health Organization in Geneva, Switzerland and welcome to this afternoon’s briefing. Today we are now ending a day and a half conference of epidemiologists. With us today is Dr Michael J. Ryan who is coordinator of WHO’s Global Alert and Response programme. Next to him is the meeting chairman, Angus Nicoll. Professor Nicoll is from the UK’s Health Protection Agency. Next to him, Margaret Chan who is Director of Hong Kong’s Department of Health. And we also have with us Dr Arlene King from Health Canada. So I’ll turn this over to Mike now.

Dr Michael Ryan: Thank you Dick. Yesterday and today WHO has brought together epidemiological partners from around the world from 16 different sites, 6 of those sites hooked by video technology and 10 sites present at the meeting. This meeting was really to continue the active discussions we’ve had on a weekly basis with our epidemiologic partners around the world, looking at the key parameters in this outbreak response, looking at the future of the epidemic and looking at the control measures that we have in place. This meeting is now just ending and we’ve had very thorough discussions, very interesting discussions and I’ll pass over to the chair of the meeting, Professor Nicoll, to give us some sense of how this meeting went. Thank you.

Professor Angus Nicoll: Thank you, Mike. I mean this was a meeting it was a privilege to chair because it represented the sum efforts of people working in very many countries, including those who are most …, have been the most affected. We’ve been looking, as Mike says, at what the key determinants of the epidemics that have taken place, learning very much as to what has been successful – and I’d like to emphasize the success stories that we have from, say for example, for Hong Kong and from Canada where they do seem to be getting the epidemics under control. But we also recognize the huge challenges that there are for the future, particularly for our colleagues in mainland China where much of the current transmission seems to be taking place. The emphasis was on sharing of data and sharing of information and I can’t overemphasize how well that has been done between places. There’s a lot that have now been learnt about the epidemic and those will be published in a consensus document that comes out of this meeting. Much of it is actually reinforcing the information that WHO and national authorities have already published, but they also identified a number of key areas where more is needed and international studies have to be undertaken, coordinated by WHO. And I’d particularly like to emphasize the work that’s been done, in a number of individual countries, of getting colleagues in hospitals, epidemiologists and laboratories, to work together in the current goal to try and get this infection – the first emerging infection of significance in the 21st century – back in its box where it belongs. But I’d like to pass on now to Dr Chan who’s been leading the effort in Hong Kong and particularly to ask her to be speaking over the effectiveness of the control measures, what the group this day concluded was working.

Dr Margaret Chan: Thank you, Angus. It is indeed a real pleasure to be able to attend this global meeting on the epidemiology of SARS. The coming together of colleagues and friends from different countries, particularly those affected by SARS, is important. It provides a venue for us to share information and experience and to learn from each other. And the striking thing after this one and a half day meeting, coming away from the meeting, is that the similarity of the pattern of the outbreak in different places and the application of public health measures – albeit slightly different but basically very similar involving early identification and isolation of patients and management of close contacts by home confinement or quarantine and other public health measures like education and also perhaps border control – these seem to work in specific settings, in Hong Kong as in other places. And that’s a reassuring message, because the sharing of experience could be, you know, at the end of the day, promulgated in the form of a consensus document and countries that have not been affected by SARS could take reference from this document and they can prepare themselves in terms of crisis management and emergency preparedness. So I think this meeting is very important and it is very timely and I thank the World Health Organization for coordinating the meeting.

Dr Arlene King: Yes, we too feel very privileged to have been a participant at this meeting and had the opportunity to really review all the current evidence, epidemiologic evidence, with respect to trying to better inform our disease control measures, both nationally and globally. And I think this will be very, very important to future control of this disease, certainly in places like mainland China where challenges exist with respect to disease control, and with future control of the disease globally. I think for me, the reaffirmation of much of what we know currently about the epidemiology has been extremely important, and the opportunity to share information on emerging information with respect to disease control has been critically important. And again the appreciation to World Health Organization colleagues and also to my international colleagues for sharing this information so readily.

Mr Thompson: OK. We’re going to take questions now. You can dial in questions by pressing 14 on your telephone. I’m going to ask Dr Ryan to identify the person who will respond to the question for those people who are listening. Thank you, now we’re ready for questions.

Associated Press: Yes, hi everyone. Can you tell me what is the consensus of opinion of the future of the epidemic globally and in China, as far as putting it back in its box and what challenges there are, if you still believe that’s possible?

Dr Ryan: I can take that question. Hi Emma. I think the really important fact coming out of this meeting is that the experience across the range of countries involved has been that the control measures that we have designed at the beginning of the epidemic have worked. And in country after country we have managed to break the cycle of transmission through the simple implementation of case finding, contact tracing, and isolation practices in hospitals. This has been the key factor and we’ve seen the number of secondary cases per case dropping systematically in all of the countries to a point now where we believe, in the majority of cases, we are now seeing the epidemics coming to an end. We still have a difficult situation to face in China. The problem is very large. It’s not any more complex than it is in the rest of the world but it is very large and we need to assist our Chinese colleagues in implementing the same measures in a very aggressive manner in China, as the Chinese authorities are doing. So, yes, I think the message coming out of this meeting is certainly one of great hope, it’s one of celebration that the measures are working but also a call to action because we’ve got a lot more to do yet before we end this problem.

Professor Nicoll: Mike, could I just add one thought to that. I think one of the important messages is the importance of having good public health infrastructures that are linked up to government and also to clinical services. Because I wouldn’t like to answer the question making predictions about what’s going to happen. I always like to quote an American saying: It’s very hard to make predictions about the future. Our job, actually, as public health officials isn’t to make predictions, it’s to have in place the mechanisms so when, either this epidemic or the next one appears, surprises us, that we can detect that surprise and respond to it in a timely fashion.

USA Today: Thank you. I’m wondering if you also talked about mistakes that were made, or what you’ve learned from missteps that were taken along the way and what those might have been? And also, how will this change the way medicine is practised, going forward, the way hospitals are handling new patients, that sort of thing?

Dr Ryan: I can maybe address that and then pass it on to colleagues. I think it would be wrong to talk about mistakes. I think the measures that have been applied have been advised from day one and those measures are effective. I think that the lessons coming out of this are really ones that Professor Nicoll mentioned. It’s about having in place good preparedness measures, good communication systems between the different sectors of government, good early decision-making and systematic implementation of what’s decided. That requires, in a crisis, all levels of government, national, sub-national, different sectors within the government and with the private sector as well including hospitals, to work together. And I think the lesson coming out of this is: managing an outbreak as serious as SARS requires very, very good collaboration between all services. And I think the lesson for the future for us, as Angus said, for any future epidemics is really one of how we organize ourselves and we probably need to do that better in the future.

Professor Nicoll. Yes, I wouldn’t talk about mistakes, I would talk about vulnerabilities. I think the sort of things that Margaret and Arlene and their colleagues experienced could equally well have happened in the country I’m based in, in the UK. For example, I think that our hospitals would have been equally as vulnerable to somebody coming in with SARS at an early stage. So that, I know for our country that our chief medical officer has issued guidance to all of the hospitals so that they are not as vulnerable as they were in the past and that they are now as well protected as I know Margaret and Arlene could speak to in their countries.

Dr Chan: Yes, I would like to perhaps profile my own sort of experience on the lessons to learn. I certainly agree with my colleagues that, you know, capacity, in terms of infrastructure and systems to collect intelligence, is important. And without information, without intelligence, you don’t know which way you are going. By that I mean infrastructure for disease surveillance is hugely important and once you have that information then comes the point about risk communication. And I still recall, in the situation of Hong Kong, when we were first confronted with this outbreak, we had no idea what we were dealing with, we didn’t know what the virus …, we didn’t even know it was a virus, and you just have to depend on a good system, good people to do the work to the best of their ability. And as you move along, don’t be afraid to tell people that you don’t know what you are dealing with and also ask for regional and even global assistance through the WHO or other agencies. And this is perhaps one lesson we all can learn. SARS is too big for any country to handle single-handedly. It calls for regional and global collaboration, and the collaboration has been unprecedented in terms of identifying the virus, characterizing it and coming up with quick diagnostics and sharing of information on the management of patients and on public health control measures. I think, all in all, we have more success stories than mistakes. But, I mean one should not be complacent. And this lesson also teaches that whenever we are dealing with communicable diseases, the notion of modesty has to be there so that we are better prepared.

Associated Press: Yes, hi. Can I talk about Margaret Chan’s discussion about the outbreak pattern being similar across the world? And then, also Mike was saying that China is no more complex … can you explain a bit more what are these elements of the outbreak pattern that are so similar and is the fact that China is larger, does that not make it more complex? Or in what is it no more complex than the other places?

Dr Chan: In the last one and a half days, during the meeting, we shared experiences from 16 locations. And what we see in terms of the epidemiology, the mode of transmission of the disease, like say for instance, droplet transmission versus airborne, I mean that is coming out very clearly. The evidence is there to support droplet, close distance spread and the information on incubation period and the information on public health measures. Now these are all important patterns to help us to address the problem. Other features like health care setting is definitely a high risk area, close contacts, including family contacts would be areas that you have to address. And what about travel advice? And all these are very similar and the emerging of information from different settings are similar.

And you are quite right in saying that, notwithstanding the fact that the patterns of the outbreaks in different countries are similar, the issue may be very different in mainland China because of its sheer size and because of the complexity of the situation. So you know, meetings like this are valuable in transferring information and best practices to mainland parts and also to other countries who have been lucky and not been affected by SARS so that they can think in terms of emergency preparedness.

Dr Ryan: Maybe if I could add to that. Because we’ve had our colleagues from China here with us over the last two days and it’s been great to see that the Chinese have increasingly got better and better data. They really do understand their problem now. And they were able to present some very interesting data on their epidemic and how their epidemic is evolving. And this is a very good sign because it means that the situation in China is beginning to be understood very, very clearly and China is fully engaged now with the international community in terms of the implementing of control measures. And very, very anxious for international collaboration in controlling SARS in China. And that’s a really, really positive message because if we’re going to do this in China, we need to be good partners with China and China is very open to that partnership.

Dr King: In the beginning, I just want to reaffirm that, from my point of view, the information shared by the Chinese at this meeting has been extremely helpful in, certainly, informing global practices with respect to disease control. And again, as has been stated before, the issue of the modes of transmission, for instance close contact being required for transmission to occur, was certainly underscored. Additionally, again the problems in China are similar to those that have been faced by most of us, which is concerns related to, again, close transmission settings like hospitals and households where it has been again the predominant place where transmission has occurred. So these kinds of common issues are ones that have been observed globally and certainly continue to be observed in China and will require ongoing vigilance.

Associated Press: And the faecal-oral thing, has that been clarified at all or not?

Dr Ryan: The evidence thus far is that this epidemic has been very much driven by close personal contact, aerosol transmission to close personal contact between individuals. In certain other circumstances, the aerosolization of faecal matter may have played a role. At this time, there is not a lot of evidence to suggest that the faecal-oral route is playing a part in driving this epidemic. However, it is known that this virus can be excreted in the faeces and therefore we have to look at this issue. And that’s one of the issues we’ve discussed – how we can best study the role that this might play. But the evidence that exists right now …, we know that the epidemic around the world and all of the wonderful data that’s been collected by the people in the different sites, is that they can establish this close personal contact as the cause of infection in the vast majority of cases. And this is reassuring, it’s not reassuring in the sense that it’s terrible when people become infected, but it does indicate that we do know the major modes of transmission. The contribution that other modes might make are important and we need to study them more. But this is nothing to be concerned about at this present time, we need to study this but this is not driving the epidemic, as far as we understand at the present time.

Scientist: The question is regarding the research that’s needed in future. You specified at the beginning of the conference that the meeting had identified several areas that are open and require study. I’d like to know what those are and what studies are likely to be undertaken? And secondly, I wonder if I could ask Dr Chan if she could possibly preview the Hong Kong report which I think is due out on Sunday, about the Amoy Gardens transmission route?

Professor Nicoll: I’ll try to be brief, Robert. The details will come out in the consensus document. A lot of the research work is actually that already under way but what we’ve achieved here was an agreement to share the data so that we can better define on areas like the incubation period, though we think that the current WHO statement on incubation period is correct with the data that’s available, and similarly as to when people are infectious. And again, we are reiterating that there’s no sign of infection coming from people before they start developing symptoms and that you seem to be becoming most infectious in the second week, but you have to treat as though people are infectious right from the start. So, it’s really not so much that these are new studies, that really is to say we are having an international approach to studies where the data is already there. But I’d like to pass on to Margaret for your second question.

Dr Chan: Robert, thank you for that question. The outbreak in Amoy Gardens in Hong Kong, as you may be aware, the Hong Kong government has actually involved many government departments to assist us with the first phase investigation and we came out with a report and that was released earlier. And we found that a collection of factors had to be in place at about the same time to lead to the outbreak in Amoy Gardens. And subsequent to our investigation, we felt that it is important to share our information and also what is happening in Amoy with our international partners. So we invited Health Canada, under the aegis of WHO, to come to Hong Kong. What they did was, they sent experts who are very good with sick buildings, they sent scientists who have environmental expert background. So, to make a long story short, they spent about three weeks in Hong Kong and they have finalized their studies and the report will be released soon. I’m not sure whether it has been released or not because of time lag – I’ve been in Geneva for a few days now – so the report will be coming out. And before I left, our discussion with them is, they concur with the major findings that have been reported by the Hong Kong government earlier. Basically, in a nut shell, what it takes to cause the Amoy Gardens outbreak would be a collection of factors. Number one you need to have an index patient who was causing the infection perhaps to a dozen of other people living in the E block of Amoy Gardens. These people subsequently suffer from symptoms and one of which would be diarrhoea, and also I’m sure the malfunctioning of the flushing system and also the sewage system, plus the emptying of U-tube of the bathroom floor drain – all these have to occur at around the same time to cause this SARS outbreak. And so the lesson to be learned from here is that we should not change our practices without making appropriate adjustments to the environment that we are living in. So that lesson to learn is that ….

Scientist: OK, so that confirms that the faecal-oral route is part of the transmission route then?

Dr Chan: We must be careful not to create a situation where an outbreak can occur.

Scientist: OK, can I quickly go back to the first question – what about the reservoir? Is that not an issue in China?

Dr Ryan: Obviously, we would like to establish the origin of the infection – that is an issue. But that’s not an issue for controlling the disease right now and we need to focus on that. We are in active discussions with the Chinese authorities with how we can better understand the origins of the outbreak. And that will help us better understand for the future, that is in hand, is being done.

I’ll just pass back to Angus, he wanted to come back on one of your points.

Professor Nicoll: There was another point, Robert. I made the point about international cooperation but also we made the point of the interdisciplinary cooperation and the need to ensure that the people who’ve got the data that is from the laboratories, from the hospitals and from the epidemiologists and the modellers, all combine together. Because it’s only when you bring all those together that you can really answer the questions that pertain to taking public health action.

Mr Thompson: Operator, this is Geneva, I’m wondering how many questions we have on-line. Can you tell me that?

Operator: Seven questions more.

Mr Thompson: OK, we’re going to continue another 10 minutes. If we could have the next question please.

Washington Post: I was wondering if there was information that came out of this meeting that might cause you to adjust any of your estimates that have been made previously about …, well you’ve talked about the incubation period, but about the mortality rate, about the routes of transmission, anything like that?

Dr Ryan: No, in fact, reviewing all of the data, it’s been a very clear consensus that the estimates made by WHO are actually still rational and still valid. But we have to look at various potentials for outliers and we are doing that, but we are very comfortable as a group right now that the current advice from WHO across the range of the different parameters is rational public health at the moment.

I’d just like to come back quickly to a point that Robert made. I think you said at the end that "this confirmed the faecal-oral route of transmission" in Amoy Gardens. I think that is not true. I think that what Margaret was trying to say is that the aerolization of faecal matter in a very specific situation may have caused infection and I think that’s an important fact. It’s not confirming a faecal-oral route for the disease. Maybe Arlene has a point on that.

Dr King: Yes, in fact I think that the issue of aerolization is obviously an important issue of infectious materials in general. And certainly we’ve seen from our experience in Canada that aerosolization of infectious materials, respiratory droplets for instance, can result in disease transmission. And I think that the Amoy Gardens is illustrative of the fact that you can also aerosolize other sources of infectious material, potentially things like faeces or urine, that can in fact be inhaled similarly to …, or have contact with mucus membranes, for instance, and result in infection through that mechanism. So, it really is a reaffirmation of what we already know around the way this disease is transmitted.

National Public Radio: Thank you. I wonder whether you have any information that came out in this conference about the spectrum of disease, about the possibility that some may be asymptomatically infected or have mild cases that are not recognized – what do the currently available tests tell us? And how they can be best used? Any data on animal surveillance? Anything on super-spreaders and that phenomenon? I’m just trying to get a sense of what the actual science was that came out here that’s new and illuminating?

Professor Nicoll: I’m going to sound a bit disappointing in saying that there was not a lot that was new here. In reviewing the information, they didn’t find any evidence of spread from asymptomatic individuals. There are one or two circumstances that need further investigations but they didn’t seem to be reporting that as a …, nobody was reporting that as a phenomenon. Similarly, we weren’t reporting that people were infectious before they developed symptoms. But clearly there’s a lot more information still to be out there. We touched on the area about looking at animal reservoirs but that, as Mike has said, is really down-stream, work particularly to be done with colleagues in China.

Dr Chan: I’d like to perhaps comment on the notion of a super-spreader versus a super-spreading setting. It is important to differentiate the difference because we must ask ourselves when an individual can cause infection in many other individuals, we have to look at whether or not the setting or the environment provides other measures or factors that is conducive for him or her to cause infection in many other people. And the issue about whether or not this person is sick at this early stage or at a very late stage. We believe that …, from data from different countries, is that if the individual has been sick for a week or more and he’s more prone to cause the infection in many other people, and if he’s a very sociable person, I mean, coming into close contact with many other individuals and so on and so forth. It’s important as a public health official or agency for us to look at the factors that give rise to a super-spreading sort of setting.

Dr Ryan: I’d like to come back to this issue of sub-clinical infection. What we’re looking at right now is a disease that probably expresses itself through a clinical syndrome. And there clearly may be cases where there are sub-clinical …, and there is some evidence that there is a proportion of cases that may be sub-clinical. I’d like to reiterate what Angus has said, there’s no evidence whatsoever that such cases have transmitted disease onto other people and that’s a very important aspect from a public health point of view. Secondly, I think a lot of these questions …, we’ve come together as a group, and we’ve been working over the last two days on defining a minimum data set globally for how we can actually share formal data globally to get more precise on a lot of these estimates. And a lot of work over the last two days has been trying to bring together the data in our various databases into a common global data set. And that will be a really important project if we’re ever truly to understand some of the more complex aspects of this epidemiology.

National Public Radio. Ok, may I just add to that. Is there a consensus emerging, at least among this group, that it’s wrong to think about super-spreaders as a host factor? That these are really circumstantial and perhaps environmental and timing factors and that there’s nothing about particular individuals that makes them super-spreaders? Or not?

Dr King: I think this is a very good question. And it’s really a very complex epidemiologic phenomenon of the factors around both the host and the environment that are really, really important to the super-spreading phenomenon. It’s certainly not simply a host factor, i.e., how infectious the individual is, when in the course of the disease they are. Those are important contributing factors but the setting also has to be right. And certainly we’ve seen that hospital settings, settings where there is really close contact with a lot of other individuals for instance, enable that super-spreading phenomenon to occur.

Dr Ryan: This cycle of super-spreading can be stopped by early isolation. Many of these super-spreading events have been driven by the fact that individuals who were infectious spent a long time in the community while ill. So not only had they potentially a host factor that led them to excrete virus, maybe in a larger dose, but they had multiple opportunities to spread disease. And I think the key factor here is to focus on the super-spreading event and how do we prevent them. And the way we prevent them is by identifying cases early before there’s an opportunity for super-spreading to occur, whatever the circumstances. And that’s really the consensus that’s coming out of this meeting.

Dr Chan: I’d like, if I may, to make an additional point along the lines. Studies will be coming out some time next week and that has been done by the University of Hong Kong people in conjunction with Imperial College in UK. And clearly the study demonstrates that early medical attention to facilitate early identification of cases and isolation of cases has huge impact and influence on the dynamics of the epidemic. So that’s why, you know, this kind of study is important for public health decision-makers to come up with the right kind of message to the community so that people suspected of suffering from SARS should seek early medical attention.

CNN: Going back to what you might have learned from some of the Chinese participants, and it’s unfortunate that they couldn’t participate in this press conference, but can you tell me what they have learned recently versus what they knew early in the spread of the disease? Especially when it comes to, what you just told us about, which is that early isolation can help reduce the spread? The world has known about SARS for two months now. China’s been dealing with atypical pneumonia for a lot longer than that and even now it’s still spreading quite a bit within mainland China. What have your colleagues from China told you? What lessons have been learned even to this date, even though some have been known for two months?

Dr Ryan: I think if you go back and look at the experience in places like Hong Kong, there is a point in every epidemic where the problem seems so large that there’s a real sense that it’s out of control. Because the benefit of your public health interventions is weeks ahead. Whatever you do now will not have a direct impact on the epidemic for another one to two or maybe even three weeks. And I think the difficulties in China is that they’ve got multiple epidemics, as such, multiple clusters of cases and they have an incredible amount in terms of case finding and contact tracing. And I think we reviewed with the Chinese the measures they are putting in place in terms of case finding and contact tracing, and I think what’s happened over the last few weeks is the application of those measures has become much more systematic. The capacity of the Chinese authorities to measure the disease in the community and centralize and get that information to decision-makers, has increased dramatically. And they are not being able to isolate patients more quickly. They are able to identify contacts more systematically. And I think this is going to have a positive impact on the epidemic but the force of infection has been that high that it’s difficult for us to see the benefit of that. And I think we are seeing the benefit of that in Guangdong and hopefully we’ll see the benefit of that in the other provinces in the coming weeks.

Professor Nicoll: Yes, I think I want to reiterate that this was a meeting which was taking place through video conferencing and so it’s very difficult for people to participate in this press conference when they’re actually abroad. But what I was hearing from colleagues in all parts of China who are taking part in this was that they were learning very much from the experience, like from Margaret and from Arlene, and they are now applying those methods where the transmission is taking place. I was very impressed that they had learned the lessons, as we’ve learnt the lessons for the United Kingdom. I hope we don’t face what they are facing in China.

CNN: Just as a followup – you have been discussing routes of transmission. Could you address some of the rumours that are out there on how it may be spread and tell us if you know about that, for instance that, evidently it has been put out in the press in parts of China, is that dogs can spread the disease? And other animals can. What can you tell us to be very clear to those who are interested in this, how, you know, it can and what we can say about how it cannot be spread?

Dr King: Well, even though organisms can sometimes be found either on animals or in animals, there certainly is no evidence that animals or insects or any other non-human things are spreading this infection or are really a significant contributor to the epidemic, either in any of the countries or globally. And certainly we reaffirmed at this meeting that the mode of transmission is primarily through respiratory droplets. There are certainly things to be learned about other possible modes of transmission, including things like contaminated articles in someone’s environment. But no evidence to date to suggest that animals or insects play a role with respect to transmission of infection in any setting.

New York Times: Yes, after you are through could you spell the names of all the participants because that wasn’t done at the beginning.

To go over several points in clarification, here. It seems contradictory to me in terms of the remarks that were said about faecal-oral. On the one hand you were saying that faecal-oral wasn’t a prime mode, but then you were saying under the circumstances, it could be aerosolized and it depended on the circumstances and that could be urine or faeces and it could be by touch – that sounds to me faecal-oral. Two, in China the complaints from the WHO has been that the vast majority of recent cases haven’t been able to have been traced to a contact – are you saying that they are now able to do that or is that still a problem? And three, there was earlier studies from the Imperial College in London with Dr Chan and Hong Kong that were suggestive that the incubation period was much longer – can you address that? And lastly, was there anything about the criteria for determining whether SARS could become endemic in a country? And I guess, lastly, will there be a transcript of this?

Dr Ryan: Let me try and then pass it on to colleagues. The first question – faecal-oral. I think what we trying to explain that in epidemiology and in public health, as you know, Larry, the concept of faecal-oral transmission is about the majority of transmission being by that route like with an enterovirus or with another viral pathogen. And what we are actually saying is that, yes there are specific circumstances in which we have documented potential spread through the aerosolization of faeces, but haven’t documented spread through that normal faecal-oral route as you would imagine it with another enteric pathogen. I think that’s the distinction we are trying to make at this point. On the second point of tracing contacts, you are absolutely right. The Chinese are making great strides in identifying the contacts of cases, some of the most recent data indicates that for the cases they have found in tracing backwards, they can’t always identify the chain of transmission for which that person was in. And that is an issue because there are many factors that might explain that, one of which might be whether or not there’s another infectious process going on or a concurrent respiratory disease in the community at the same time. On the incubation period, I think Roy Anderson was here …

Professor Nicoll: I can deal with that. The Imperial College group, Professor Anderson and Margaret who are at the meeting …, the data were reviewed and a commitment taken to enlarge the data set, getting information from other countries, so we’ll have a more .., an even stronger scientific base. But having said that, the group as consensus has agreed there was no reason to change the incubation period that has currently been stated by WHO with an upper limit of 10 days. There are individuals that are beyond those 10 days but what has also committed itself to having a protocol for looking carefully at those cases to make sure that the data and the classification was correct for those. I’d like to pass on to Margaret for the fourth question.

Dr Chan: Thank you for that question, I think this is a very important question. We often get asked whether or not SARS would become endemic. Well, I think from the public health perspective, we are working with two theories in parallel. On the one hand, we must not relax our measures. We should double our efforts and try our very best to eradicate the disease as a first objective. Having said that, whether or not the disease could become endemic, it would require more time to observe it and there is some agreement that it would take at least a calendar year to see how the disease would evolve. So it has public health implications, by that we mean for places that are already affected there would be a strong need for us to do our best to prevent it from gaining a firm foothold in the community. And so, notwithstanding we are seeing some early successes in terms of control of outbreak in Hong Kong, I have committed to maintain the basket of public health measures for at least a year, if not more.

Mr Thompson: OK, there will be a transcript. I’ll repeat the list of participants. I want to thank them for their participation today in going longer than they intended – thank you very much. Michael J. Ryan is the coordinator of WHO’s Global Alert and Response programme. Dr Margaret Chan is the Director of Hong Kong’s Department of Health. Angus Nicoll was the chairman of this meeting. Professor Nicoll is from the UK’s Health Protection Agency. And Arlene King is from Health Canada. Thank you very much. See you Tuesday.