Global Alert and Response (GAR)

Severe Acute Respiratory Syndrome - Press briefing

Thursday, 27 March 2003, 15:00 Palais des Nations

World Health Organization

Dr Mark Salter, SARS clinical management network
Dr David Heymann, Executive Director, Communicable Diseases
Dr Klaus Stohr, Scientist, CSR
Dr Max Hardiman, Scientist, CSR
Mr Dick Thompson, Communications Officer

Mr Dick Thompson. Hello, we're here today to talk about the announcement from Hong Kong University, to talk about travel advice, we're also going to report on yesterday's virtual meeting of 80 physicians who are treating SARS patients. The transcript for today's press conference will be on the WHO Web site in a few hours. We are also putting on the Web site a transcript of a press conference that was held in Hanoi today, and tomorrow we'll have a transcript from the expert team in Beijing.

With us today to my right is Dr Mark Salter, coordinator of the SARS clinical management collaborative network, Dr David Heymann, Executive Director of Communicable diseases, Dr Klaus Stohr, coordinator for the collaborative network of SARS research laboratories, and Dr Max Hardiman, Project Leader for International Health Regulations.

Dr David Heymann. Thanks Dick, and thanks to all of you for coming today to talk with us a little bit more about SARS. We have had now two updates from China over the past 24 hours and our collaboration with China is certainly intensifying and deepening. We do anticipate that we will be working with China on all aspects of this outbreak, including their laboratory and clinical people in our virtual working groups that meet by telephone and also for collaboration with our team working in China.

As you know, yesterday China reported 792 cases and 31 deaths of SARS in the Guangdong province. This was reported from 16 November 2002 to 28 February 2003. Now there is a definite link established between the probable cases in Hong Kong and the probable cases in Guangdong. Today, there have been 10 cases reported from Beijing and 3 deaths. To date, we don't know in what period of time these have occurred; 2 of these cases are in health workers. In Shanxi (CORRECTION) 4 cases and no deaths up to 26 March, and again 2 of these cases are in health workers. 30% of those cases that occurred in Guangdong have been in health workers as well. So as I say, the link is clearly established now between Guangdong and Hong Kong, the Government of China is deepening its collaboration with WHO on all fronts, including in the field and in WHO's virtual discussion groups on clinical and diagnostic criteria, on laboratory and on epidemiology. Thank you.

Dr Mark Salter. I'd like to report today that yesterday a unique event in WHO was the establishment of a collaborative network of clinicians all currently attending patients with SARS from around the globe was assembled. This involved 80 physicians from 13 countries who came together to exchange their experiences of dealing with SARS patients to give us a clearer understanding of the presentation of the disease, the progression of disease, and the likely effectiveness of any therapies that have currently been employed. What we were able to establish is that within the SARS group of patients, there are two groups. One group makes up the majority, about 90%, who will have all the characteristic symptoms upon presentation, will progress to about day 6 or 7 and then will spontaneously start getting slowly better. The other group, the remaining approximately 10%, has a more severe form of the disease and progress to acute respiratory distress syndrome, many of whom will require mechanical ventilatory support. The mortality among this second group is quite high and early indications from my clinical colleagues suggest that most of these who do succumb actually have significant other illnesses at the time of presentation. We hope that this clinical group will in the future will be able to bring together all of the experiences, particularly those relating to the effectiveness of therapeutic agents, to more speedily come to an agreement upon what effective therapies actually exist so that there are not significant drains on resources in pursuing ineffective avenues of therapy. Thank you.

Dr Max Hardiman. Travel concerns throughout this disease have been one of the things we've had a lot of enquiries about and a lot of worries about. There are three major issues around international travel and the disease: Is the disease going to spread around the world because of people with the disease travelling from affected areas to other countries? Is it safe to visit these affected countries? Is it safe to fly in aeroplanes because there might be somebody who carries the infection on board the aeroplane? WHO issued travel guidance very early on in the outbreak and we have reviewed this many times. We are now at the stage where we are going to step up our recommendations with regard to travel. In particular, we are going to focus on reducing the likelihood of people who are infected with SARS undertaking international travel from the areas that are affected - the main affected areas, i.e. the list that is on the WHO Web site. We are going to do this by recommending that people departing from these areas be screened for symptoms or signs of SARS. People who respond positively in that screening would then be looked after in health care situations and would not be allowed to travel. We are also going to issue guidelines for how to cope with the situation where somebody is ill on a plane and you're not sure whether this person is SARS or not and how the aircrew can manage that situation so there is very minimal risk of any exposure to passengers or aircrew and that the follow-up of any contacts of a suspected case can be carried out internationally.

Dr Klaus Stohr. The first phase of the hunt for the causative agent of this disease nears completion. The majority of the laboratories in our network find corona virus in specimens from patients with SARS. At the same time, the second phase is beginning. The second phase is the development of a diagnostic test. These two phases overlap. We have to double and triple check that the corona virus is the causative agent and that takes place. At the same time, a diagnostic test has to be developed for the corona virus. These tests will be used tomorrow or beginning tomorrow, in Hong Kong. Three laboratories in Hong Kong will use two different tests and will identify SARS patients in Hong Kong. These tests will then be further rolled out to other countries quickly.

Q. In stepping up travel recommendations, can you be a little more specific. Is WHO now issuing travel guidelines that people from the affected areas should go through some screening before they can get on board the aircraft? Who will do this? Is it the local authorities? Are there any guidelines for people going to the affected regions?

A. Dr Max Hardiman. Yes, it's a very simple screening procedure that we are recommending. It's a matter of answering two questions about possible symptoms that a person might have of SARS and about contacts with possible SARS cases. Those questions can be carried out in the same way as the security checks are carried out currently at check-in. Of course the people doing that kind of work are not health trained, so if there is any doubt about whether the person is positive, answering that they have symptoms or that they have been in contact, then they can be referred to a health care worker. This is going to be a difficult thing for the authorities to manage because they will need extra health staff at airports. But this is important to reassure the rest of the world that everything is being done to prevent the spread of this disease further afield.

In response to your second question, we are not recommending any restrictions to travel to any destinations. That recommendation still holds.

Dr Heymann. Let me just add to what Max said. Countries still have the option of making their own recommendations. We make a global recommendation for international spread, but countries may find that because of other situations than just the epidemiology that it is necessary to advise their citizens that travel should not be done. This would fall within the scope of what we have provided, and we understand that countries may do this for a variety of reasons, including the fact that they may not be able to have insurance to cover their workers in those countries so they want their workers not to be at risk, or what the insurance companies feel is a risk. So we have allowed countries to make their own recommendations.

Q. Two questions if I may. First of all you say now, Dr Heymann, that the Chinese are cooperating but I've seen various newspaper stories that say they have been extremely lax in the beginning, at the end of last year when this was spreading in the Guangdong region. And apparently still today the provincial authorities are quite helpful but the Ministry of Health in Beijing is still dragging its feet in making these statistics known, as indeed they seem to have done in the cases of the early onset of AIDS in China. Now why are they doing that? Is there any political reason, are viruses in any way connected with socialism or communism or something?

A. Dr David Heymann. Well I think we all know that infectious diseases know no borders and they respect no borders. Our understanding is a bit different. Our understanding is that there has been full collaboration with the Ministry of Health, that decisions are presently being made above the Ministry of Health and these include discussions with decentralized provinces, which in certain instances over health have more authority than central government. So we understand it a little bit differently and this is a very complicated negotiation that is going on between the various groups concerned, but we are very optimistic that information has now got to the very high levels of government and that there is attention being paid to these issues.

Q. The second question. You said in the beginning that a close contact is really the only danger of infection. You said when we were sitting in this room that nobody would be at risk unless we are sitting next to you. But apparently travelling in an aeroplane where ventilation is not optimal anyway is now also considered a heightened risk. Is that correct? Your colleague said that pilots have been given instructions if somebody gets ill on the plane to take action. We would like to know what kind of action. Are they being isolated?

A Dr Max Hardiman. The kinds of contact that have resulted in transmission of this disease I think you've probably heard about before: heath care workers and then in their families. We say close contact. Now close contact can take place in a number of situations, including on aircraft, and we have always been aware that there is the possibility that such contact could take place in an aircraft or in any situation where you are very close to other people. We had no evidence to suggest that it was happening in aircraft until a recent case in Hong Kong, which you probably are also aware of, which seems to be linked to a probable case on an aircraft, which infected others. We have defined what we mean by a close contact within the aircraft situation in the guidance that we are sending out. This is based on the best evidence that we have at this moment. As we learn more about the disease we may change that. But in fact we still think close contact is the important factor and it's not that the whole of the aircraft is going to be at risk, but those who are close to the person who is sick on the aircraft. That person can then be isolated, they can wear a mask, and that will cut down any risk of exposure enormously. But the other thing important to remember is that on an aircraft you don't usually have someone who is capable of making a decision, "this person is a case of SARS" or not. So what you are generally dealing with is someone who becomes sick on an aircraft and causes concern, and in order to reassure the passengers that they are getting the least opportunity for exposure possible that person can be isolated from other passengers and crew, can wear a mask, and can then be assessed when they arrive at their destination to see whether there is a possibility that this is SARS or not and the appropriate follow-up steps for any close contacts.

Q. What is close contact aboard an aeroplane? Sitting next to a passenger?

A. Dr Max Hardimann. Sitting next to a passenger, sitting in the same row, or sitting two rows in front or two rows behind. Also the stewardesses or flight attendants would also be included as close contacts. Dr David Heymann. I might also add that there has been great concern expressed by you about community spread. As I have said, as we have all said in the past, to date there have been no cases which couldn't be linked in a chain of transmission from one person to another. Now as the epidemic continues to go on, we are hearing that it is more and more difficult to find those source patients in the next succeeding generations of cases. That is why it is very important now for us to have the Guangdong information, which is four months' worth of information, which will help us understand if in Guangdong there were cases which could not be traced back to another case. But in areas where there are many many cases, such as Hong Kong, it is becoming more and more of a job to do all the investigations and to clearly link at this point all the cases with another case. But that is not to say that there is not a link. It is only to say that as the epidemic increases in numbers it is more difficult to trace those contacts.

Q. Are you issuing a list of countries that should undertake this screening, or if there isn't a list is there a case limit, or what is the definition?

A. Dr Max Hardiman. We have on the WHO SARS Web site a list of what we have called "affected countries". These are really countries where we have evidence that there is transmission of the disease as opposed to maybe one or two or three imported cases, which do not transmit any further. Those affected countries are listed there and those are the ones where we suggest this screening be applied. The countries are Hanoi, Viet Nam; Singapore; Hong Kong; Taiwan, China; Guangdong province, China; Toronto, Canada.

Q. The two basic questions that will be required to be asked at airports before people board, do we know what these two questions are? Do you have a sample? Secondly, what about people travelling by sea, passenger liners and commercial cargo shipping?

A. Dr Max Hardiman. The main concerns have been related to air transport, but we have made the same recommendations for people travelling by sea, road or rail. The questions are basically, one question relates to symptoms, asking about fever, cough or difficult in breathing. The second question asks about possible exposures, whether you know you have been in contact with a case of SARS, whether you have worked or visited or been a patient in a hospital where there is SARS, or whether you have member of your family has been a suspect or probable case of SARS.

Q. We heard earlier that you were not working with Taiwan. Can you comment on this?

A. Dr David Heymann. I don't think that you have heard that we are not working with Taiwan. There is a WHO collaborating centre, which has actually had an expert working with the Taiwanese government since report first came to WHO. So we receive reports of SARS probable cases. We contacted one of our partners, a collaborating centre that has had an expert working with the Taiwanese government, and we have also posted on our Web site the cases that have been reported from Taiwan.

Q. Regarding the travel advisory, do you have any plan to speed up the safeguarding measures on the general situation, because some school in Singapore has already been shut down?

A. Dr Max Hardiman. I'm not sure I understand your question. We are not suggesting that countries be shut down. In fact we are suggesting that countries step up the measures that they are taking to ensure that flights leaving their countries will not have passengers with SARS on in order to prevent unnecessary disruption to travel.

Q. Some country has already advised their citizens against travelling to the affected areas. Do you encourage such kinds of moves?

A. Dr Max Hardiman. Right, I understand your question. As David Heymann said earlier, we recognize that individual countries have the right to make their own advice for their own particular nationals. Sometimes they have to take into account factors that we, in giving our recommendations, do not have to take into account, such as these insurance issues and whether you can medivac people out of that area. Those reasons can sometimes lead them to a different decision to WHO advice.

Q. On the virus that is causing SARS, are you still thinking that it might be the combination of the corona virus and the PM virus?

A. Dr Klaus Stohr. We believe that the corona virus is the major causative agent. Now the data that is forthcoming from very many different laboratories which investigated samples from Viet Nam, from Hong Kong, from Singapore, from Germany, and from Canada, all these laboratories are consistently finding corona virus in those patients. At the same time, the laboratory in Hong Kong as well as CDC have isolated a virus from patients and they could characterize this virus as a corona virus and they could also develop certain tests, and they find that this test is positive in SARS patients and that the test is negative in other healthy adults. This testing now allows in the very near future to differentiate between those people who are affected and those who are not affected. This testing will start tomorrow in Hong Kong. Hong Kong University has developed two different tests: one test looks into the blood of infected patients and sees if there are any antibodies; the other test can detect virus in the respiratory tract, for instance in saliva. These two tests in combination will allow to detect SARS patients at an early stage. These are the very good preliminary results. We need to take into account that these tests have not been validated, but this starts tomorrow. The development of these tests is the result of a collaborative effort of all the laboratories that are members of this network. Two outstanding breakthroughs or detections were made by two laboratories and that is the Hong Kong University as well as the Centers for Disease Control in Atlanta, USA. All of them are working in our WHO network.

Q. So the paramyxo virus was not the cause of this disease?

A. Dr Klaus Stohr: There are normally few diseases which are cause by two pathogens. The majority of diseases are caused by only one pathogen. Now we are seeing here consistent isolation of one pathogen in very many SARS patients. That gives us confidence that corona virus is linked to SARS. What we are also seeing is that some of these patients have another virus, a paramyxo virus. We have to find out what the second virus is doing. It could potentiate the disease, that’s one possibility. It could be a helper virus which enables the other virus to cause the damage or it could also be a co-infection and not related whatsoever with SARS.

Q. On the figures of China, Dr Heymann, you mentioned for Beijing and Shanghai we have figures up to yesterday, 26 of March. Did you have information from Guangdong? What are the difficulties? They have been reviewing what are the number of cases from March onwards. Why do they not have it?

A. Dr David Heymann: I can’t answer that question. All I can say is that we’ve been told that we will have that information very shortly. I think what’s going on is that since there is a case definition internationally that describes the disease, they’re making sure that what they report, recent reports, fit with that case definition. And although their case definition was very close to what we use in WHO world wide, there were some slight differences. So I think they’re just being doubly sure now on these cases that they have counted since the beginning of March, to make sure that they fit the WHO case definition. That’s what our understanding is from talking with the team.

Q. Also a follow-up on that. Dr Salter, you mentioned that the two groups of patients, 90% they got well 6 or 7 days afterwards, while 10% deteriorated. So I wonder what are the characteristics of the group of patients that actually turned worse? Because they are some press reports suggesting it has to do with age? Like someone over 40 or something. And do you also have the recovery rate of the disease?

A. Dr Mark Salter: I can start perhaps with the discrimination to the groups. There are approximately, 90% of the individuals seem to be recovering when they reach 6 or 7 days. We are not yet n a position to say that they are cured but we having a number of reports of individuals being discharged into the community who are apparently well but that’s obviously something that we will need to follow up on. As for the 10% that are progressing to the more severe form, the only prognostic indicators we have are for poor prognosis, is that there seems to be a greater number of older people, and unfortunately the figure 40 came out, although obviously most of us here would not consider that old. And that those individuals who progress to the more severe group had previous existing illnesses before they developed SARS. For example, they might have coronary heart disease or they might have renal impairment, kidney impairment, or they might have liver dysfunction.

Q. The 40, so it is the dividing line or what?

A. Dr Mark Salter: It’s not a dividing line. We haven’t had sufficient statistics to put an absolute figure on, but speaking to the clinicians yesterday, this is the age above which they have seen most deaths.

Dr David Heymann: And remember that the initial outbreaks are in hospital workers who have this age. What we don’t have is the full range of ages yet, hopefully we won’t have that, but the full range of ages that get sick. Because there may be a different analysis in two weeks.

Q. For Dr Heymann, a question from a lay man. Where do we stand on the, you know, you said that there are several hundreds of cases, now perhaps over a thousand, and it becomes harder and harder to track the contacts, as they proliferate. Can you give us a sort of prognosis about the shape of things to come? Is this going to be a pandemic after all or can it be stamped out? And another thing, you talk about corona virus but this is then a new variety of corona virus or is this already a well known one?

A. Dr David Heymann: I’ll speak to the pandemic question. In countries where they’ve applied stringent measures and encouraged participation of the international community, for example, in Viet Nam, the outbreak has been stopped, we believe that cases have not increased in the last three or four days and we are hopeful that that outbreak is now contained and will not continue. But we’re not sure yet. What you have to do is wait for two full incubation periods after the last case of disease in order to declare that there is no more transmission. In Singapore, measures are underway, very severe measures in some instances with quarantine which is justifiable in the Singapore situation, and they seem to be confident that they are stopping the transmission. Hong Kong has increased recently its control measures dramatically. But the difficulty in Hong Kong is that because they are so many health workers infected, who are the pillars of the health care system, it’s very difficult now to find all the extra health workers they need to increase their measures. But our word from Hong Kong today was that they’re very confident now and that they’re increasing some of their measures. Over the next 24 hours, they will be announcing this and they believe that it’s contained in Hong Kong. In Canada. there has been some transmission to health workers and they’re now containing that outbreak and we believe that’s been contained. The unknown, of course, is, number one, is there an asymptomatic form of this disease, which means people are infected without symptoms, who have been travelling around the world with this disease. We don’t know that yet. We don’t believe that’s the case, we hope that’s not the case. So the answer to your question of “will this become a pandemic?”, we don’t believe it will become a pandemic, especially because after the alert that we raised, there’s been a heightened search for cases in most countries and cases have been isolated immediately and stopped. So we think that the measures that we’ve have sensitized the world and are preventing a disease from becoming a major pandemic. And that’s our hope.

Dr Klaus Stohr: The question was, is this a new virus which has been detected. Now, three laboratories are looking at the genetic material of this virus and the data that we have so far, clearly indicate that this is a new strain which is unlike any known animal or human corona virus. In the corona virus group you have quite a few very aggressive animal viruses. You have also viruses cause mild respiratory disease, you have viruses which cause diarrhoea. In humans, you have corona viruses which cause coughing, sneezing, also those which cause pneumonia. However, this virus is none of the known viruses. That’s what the genetic analysis shows. What is important here is that, I mean, this is scientifically important to know to which family this virus belongs. What is more important now for control, is to develop tests to differentiate infected from non-infected persons; tests which would help identify a person who might excrete the virus, who may not excrete the virus. This could be a major breakthrough in containment of the disease. Therefore, a lot of time is being invested by the laboratories to develop this est. That will then help also define what is a suspect, a probably, perhaps a confirmed case, that will also then speed up certainly measures to contort the disease. The emphasis is on diagnostic tests. Of course, scientifically, it’s important to understand what type of virus we have, to which sub-group it belongs. But we need a test to differentiate between healthy and infected patients.

Q. What does the discovery of the virus mean in terms of finding a treatment then? I mean, is this going to, how quickly can this follow on, treatment or a vaccination?

A. Dr Klaus Stohr: That’s at a very early stage. We must not forget that on the 17th of March which is last, I think Monday last week, a group of laboratories started looking at the etiology and now ten days later, the virus is more or less identified. The next step will be a diagnostic test. And I think all of the resources will be focusing on the diagnostic test. Now, understanding the genetic composition of the virus will then immediately lead to deliberations about the development about specific intervention measures and the first one, as you say, is a vaccine. But again, we are 10 days in the race for the virus and we have found a major suspect already. That’s not too bad. The other specific intervention would be a drug and I’m no sure if anyone has had time to think about it. But Mark might have an idea.

Dr Mark Salter: As Klaus said, it’s very early days and in terms of actually addressing the issue in terms of the clinical pattern that we’re in patients, what is more important is that we come to understand the disease and how the host, the patient, is reacting to that organism, if it indeed is this virus. What the clinicians are doing, are working through standard therapeutic approaches which they would normally imply if patients were presenting with the disease that they wouldn’t initially know the cause of. So a number of well-described therapeutic regimes using various antibiotics have been trie.d Unfortunately, the results to date suggest that none of them have been effective in actually reducing the progress of those who would progress anyway. The drug ribavirin, an antiviral agent, has come into the frame by lots of people now, both media and clinicians, those who have actually been treating SARS patients and those of who haven’t. Ribavirin is an antiviral agent which has been proven to be effective in treating some of the paramyxo viruses like respiratory synctial virus in young children or in treating some of the more severe forms of viral haemorrhagic fever such as Lassa. However, it’s use in the treatment with SARS has been unremarkable to date. And it is hoped that now we have a large group of clinicians working together with WHO in this collaborative network, that we’ll be more readily able to assess the information from all patients that are given these therapies and hopefully come and establish what therapies are actually effective and rule out those therapies which have been proven to be ineffective, so that the clinicians can concentrate their efforts on looking at perhaps more novel approaches to aiding those who are suffering from the more severe form of SARS.

Q. Just, I wanted to clarify. Then, in fact identifying the virus doesn’t really help you in determining a treatment then, these are totally separate scientific processes?

A. Dr Mark Salter: At the present moment in time, they run in parallel, as all of these things do and at any one stage in any new disease, we are looking at all these things in one go. I think some people have the impression that we are looking at the virus isolation identity in isolation from the management of the patients, which isn’t the case. They are being looked at in parallel and the groups are working closely together. Once we actually can have a handle on the virus, there is the opportunity, as Klaus was saying, to start looking at experiments in tissue cultures to see what effectiveness therapies might have on blocking the replication of that virus in those tissue cultures. But that is only the firs stepping stone to actually developing and understanding what effective therapies there may be already in existence, or what effective therapies there may be yet to come.

Dr Klaus Stohr: The most important condition to develop a vaccine is to have the virus isolated in pure culture, either in animals or in cell culture. Then you can produce large amounts of this virus, inactivate its aggressivity, its pathogenicity for humans and test whether it causes any immune reaction in animals or people. So the condition for the development of the vaccine is the isolation of the virus. And that took place already on the 21st of March. And the first one who isolated the virus was Hong Kong University. And that was repeated and confirmed and (garble) had not been possible with the other network members, for instance, Centers for Disease Control in Atlanta. So the stepping stones are there for a vaccine but not much research has started on it.

Q. I’ve got a follow-up question to your answer earlier. Aside of the vaccine or whatever to combat the SARS, from the history of the patients that are recovering, why are they recovering, besides being on machines? Shouldn’t that be giving you an indication why some people are getting better? What are the case histories showing?

A- Dr Klaus Stohr. What’s very promising is that patients who survive SARS have antibodies in their blood and these antibodies in cell cultures, outside the patient, can kill the virus. So that shows that these antibodies play also a role, potentially, of killing the virus in the body of the patient. So which means that this virus could also be used to immunize others before they are being infected, so that they would develop these antibodies before they are being infected by the real virus. But this is very promising. What keeps people alive, actually, is what Dr Heymann kept on saying during the last week, is supportive treatment. And those patients who have the immunity to develop antibodies, they can clear the virus from their body and they will then recuperate.

Q. I want to go back to the question of close contact, because in the situation in Hong Kong, we have several hundred infected people already and for us mostly we have skyscrapers and high buildings. So going out or coming home, that means taking a lift, a escalator and I suppose that would be close contact for people to spread the diesase. Do you have any recommendation on that?

A. Dr David Heymann: The best prevention for any disease is information and understanding by people what that disease looks like and what they should do if they become sick. With that information, people can decide whether or not they want to expose themselves to what they consider at risk. It may be, for example, that somebody is coughing on an airplane andn the person next to them feels that they need to move in that airplane because they are afraid that this might be SARS. That’s a personal decision. And so, public health can’t do a lot for a disease which is a contact diseases, it has to be individuals who understand what the disease is. If somebody’s coughing, somebody looks like they are sick, the best would be for the person to be avoided by others. So that if you’re standing next to someone on a escalator who’s coughing , you ought to move back two or three steps. So that it’s a personal understanding of the disease that’s very important. It stops panic, it stops inappropriate measures, it stops trying and protect and giving yourself false security that you are being protected by something which won’t protect. So, what you people do is very important because that educates the general population as to what this disease is and how individually they can prevent themselves from beginning sick. So it’s an educational effort.

Q. So just to follow up in that case. When you talk about close contact, what exactly kind of contact are we talking, spittle? Are we talking sneezing? Are we talking shaking hands, perspiration, touching an elevator button after someone else has touched it, who is infected? Secondly, could you just remind me, I’m sure you’ve said this before, what the incubation period is? And there are numbers on, have any children been infected with SARS?

A. Dr David Heymann: The incubation period is 3-10 days as far as we understand, although information coming from Guangdong may provide more information that this is a little bit longer than 10 days. But right now we say a range of 3-10 days. Children are becoming ill, children of hospital workers who have become sick and many of these have been in school and people who are sitting by them are now also at risk. The disease. we believe, is spread by droplets but droplets which aren’t aerosolized and spreading a long way away. What I’ve always said is that in this room, the two people on each side of me would, from what we understand, be at more risk than you sitting there because this disease can spread through the air on heavy droplets and infect my next door neighbour but probably doesn’t go in finer droplets which are aerosolized which would eventually reach you. Measles, if I had measles, and you did not have measles, you could very well get measles because that would be a fine aerosol which would make it all the way to you. So this is limited to two seats in front, two seats in back of an aeroplane, we believe, close contact, standing next to someone on an escalator who coughs on you, or other issues where you are in close contact, face to face, or very close. We don’t know about perspiration, but we don’t think so.

Q. Are we certain now that this originated in Guangdong, that that is the real first focus of it and, second, is this corona virus we are talking about a virus which jumped the species barrier?

A. Dr David Heymann: The origin is really not important. It’s with us today and we have to stop it. As you look back, you’ll probably find that cases are traced back in generations and probably Guangdong will play a major role. Whether it’s the source of this outbreak, nobody can say. New viruses usually don’t come in from outer space. They come in from another organisms those viruses or bacteria, in this case virus’s. That could be animals, it could be another person who has a virus that mutates and is transforming that virus. But it’s usually which is already infecting something in nature, which either mutates or crosses this species barrier. Klaus, do you want to add anything more.

Dr Klaus Stohr: Many corona viruses of humans can be found in animals, particularly in mice. There have been tests run in China as well as in Canada and people found antibodies with traces of human corona virus in mice and also in bovines. So what are seeing is that these viruses appear to be transmissible in a way that they cause some antibody reaction but many not cause disease. These viruses change, everything changes, particularly viruses, and with the change of the virus, they might acquire new characteristics. And one of the characteristics could be species specificity, like influent viruses, they also can jump the species barrier. So that’s one of the possible explanations and research will help where these viruses are coming from. And that will also help us for the future, perhaps to anticipate the emergence of these viruses, so research is vitally important to understand where the virus comes from to see if something new might be happening in the future.

Q. About the planes again, am I too mean to think that people might lie?

A. Dr Max Hardiman: You’re quite right, of course, people can lie and that’s why this won’t be a 100% and will not prevent 100% of people who are infected from getting on aeroplanes, but it will prevent those who doing so unknowingly, because they will be questioned before hand and made to realize that they should not take the flight. Also when there is a concern, from what we know of this disease, the infections are spread when people are ill not when they’re well, once they’ve been infected. So if someone looks very ill, they could also be referred to a health care worker, even if they’ve said they haven’t had any contact or had a cough. So, we can’t be a 100% but it will help to reduce, it’s the maximum we can do to prevent people from boarding planes.

Q. What about the precautionary principle? Should all passengers on international flights wear a mast?

A. Dr Max Hardiman: No, we don’t think would be helpful at all. Why? Because, one. it’s not very feasible, two, it would alarm people to a great extent, beyond what is reasonable for the danger associated with this disease and if people who are spreading the disease are sick, once they are identified them wearing a mask will be more effective than other people wearing masks for some of the time, not when they are eating their meal and so forth.

Q. To go back to the escalator question because we do need your expert advice on that. When you mention close contact in the aeroplane, you said in the same row or two rows in front and two rows behind. So in escalator the size would be a little bit smaller than what you just describe. So if someone’s coughing in the lift I’m with, even if I try to do what Dr Heymann suggested, try to step back, it seems to me that there’s no escape. So would you recommend people to use a mask whenever they get into an escalator or something like that? Because it is a real issue for people in Hong Kong – we do it every day whenever we get out of our place and get home.

A. Dr David Heymann: Fortunately, from what we know about this disease, it seems that people who transmit the disease most are those who are quite sick, who have a fever, who are coughing. Fortunately, these people don’t often go far away from their homes and they go to health workers often. So again, I say that education is important and people who have cough and fever have just as much responsibility to go to a health worker as do people who are standing near them to protect themselves. So, it’s education, education, education, information, information, information. If everyone understands that this is a disease, and everyone nworks together, it can be stopped no matter how close people have to be and I know they have to be very close in lifts and on escalators in Hong Kong. Max?

Dr Max Hardiman: Just to say that in all these exposures, there is no complete cut off - one is a completely safe thing to do and one is a completely unsafe thing to do. Sitting on an aeroplane for a transatlantic flight, you’re there for a lot longer and so your period of exposure could be much greater and therefore a slightly further distance might actually be taken into account.

Q. So could you confirm that, there’s a news report that there will be an international conference on the SARS next week in Hong Kong?

A. Dr David Heymann: That conference, for many reasons, has been cancelled. Hong Kong has begun to cancel other events as well, as you know, concerts have been cancelled in Hong Kong. This is responsible public health. The Hong Kong authorities are attempting to minimize the possibility that people could be exposed to sick people in concert halls in other areas. So that meeting has been cancelled; it doesn’t happen to be because of Hong Kong cancelling it, it’s because it’s felt that we are getting enough information right tow on our telephone calls and it would not be of any added value to get everybody together. But that meeting will occur in the next three for four weeks, we believe.

Q. Will you change the venue?

A. Dr David Heymann: No, not that we know of.

Questions? OK, thank you.

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