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Location: WHO > WHO Sites > CSR Home > Severe Acute Respiratory Syndrome (SARS)

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Severe Acute Respiratory Syndrome - Press briefing

Tuesday, 25 March 2003, 10h00
Palais des Nations

World Health Organization

Dr David Heymann, Executive Director, Communicable Diseases
Dr Klaus Stohr, Scientist, CSR
Dr Julie Hall, Medical Officer, CSR
Mr Dick Thompson, Communications Officer

Dr David Heymann: Thank you again for coming to this press briefing. We are now 10 days into an outbreak of what we believe is a previously unrecognized disease in humans. We have cases that have spread out of Hong Kong and Viet Nam, throughout the world, and we have a laboratory group which has identified two different viruses in patient specimens. A paramyxo virus and a corona virus. At the same time, we’ve done epidemiological studies which, to date, and that means to this very minute, have shown us that most if not all cases can be identified in a chain of transmission from the patient back somehow to a family member or to a contact directly with a hospital worker or with a hotel in Hong Kong.

So studies on the side of epidemiology are also going well and as of now we still maintain that travel is not to be interrupted throughout the world at this point in time. But as you know there’s much, much information coming out of Hong Kong and there’s been a rapid increase in the number of cases this week and we are in regular contact with Hong Kong and with our Regional Office in Manila and we will be reconsidering today our travel recommendations as we do every day.

Today we will be with a group of industrialized countries that have cases as well as the countries in which the majority of cases are occurring in Asia. So we’re at the end of a 10-day period which has seen a remarkable working together of scientists, epidemiologists and countries in the world to better understand and stop the spread of what we believe is a previously unrecognized infectious agent. Thank you.

Dr Klaus Stohr: Eight days ago, WHO established a network of 11 laboratories in 9 countries. We invited these laboratories to participate in this collaborative effort to help identify the causative agent of this disease and to develop rapidly a diagnostic test. Now 8 days later, these 11 laboratories in these 9 countries have found already two very strong contenders, two viruses which are consistently isolated from many patients from very many different countries.

The research is ongoing. It is not normal that one disease is caused by two viruses. We will have to strengthen the activities, particularly as far as electron microscopy is concerned, as well as genetic analysis. These data did not become available without an unprecedented, an unprecedented level of collaboration between all these network members in all the 11 laboratories in 9 countries.

Dr Julie Hall: As has been previously mentioned, this has been an unprecedented collaboration between various organizations and WHO. WHO is working very closely with all its partners in the Global Outbreak Alert and Response Network. We’ve been able to produce guidance based on clinical and epidemiological evidence. That guidance is posted on our web site on the SARS page for all to see. We’ve established a logistic basis throughout the world and worked in close collaboration with bi-lateral arrangements from a variety of different countries to ensure that supplies are in place. As Klaus has mentioned, there’s been an international collaborative effort in terms of research in laboratories and at the back there are various sheets which you may or may not have already picked up which identify the organizations that are working within the laboratory collaboration. We also have three field teams in place.

In Hanoi there are 9 people who have been there since the 14th of March. Their key focus has been on infection control and where infection control has been put in place and has been practised effectively, we have seen a dramatic reduction in inter-hospital and community transfer of this agent. They have also been working hard in terms of clinical management and we now have a large data set of information about this syndrome which will help us to understand its clinical cause and possible effective treatments for it. It’s been shown that good supportive care has been effective and we are now in a position in Viet Nam where, now that we have developed a discharge policy, a number of patients are likely to be discharged from hospital in the very near future.

In Hong Kong we have a five-person team that has been focusing on epidemiological research and has provided a lot of data in terms of how this infectious agent has been transferred and transmitted between people and what infection control measures are required. A five-person team arrived on Sunday in China. They have a remit to review the epidemiological data that’s been collected by the Chinese authorities and also to help support the microbiology and virology investigations into this outbreak. So there has been an unprecedented collaborative effort and all the institutions that are working in the various forms, whether it be in the field teams, in the clinical network or in the laboratory network; the details of all of those are on the sheets at the back if people want to look at those.

Q. When I look at the latest figures from the WHO, it is really worrying because it seems to me that only in Hong Kong, the figures kept increasing and we have now 10 deaths. What are the factors that make Hong Kong so special? It seems the situation is not under control.

A. Dr David Heymann: Our teams are also concerned about the situation in Hong Kong because of its spread in many different hospitals and our team there is working with the government in Hong Kong, not only to better understand what’s going on in Hong Kong as far as the epidemiology or the transmission of the disease, but also in trying to stop the spread of the disease. There are people who are infection control experts working in the government and with the government to try to make sure that we can stop this outbreak. I just need to remind you though that at present there is no evidence that there is any transmission other than close contact with patients, either sitting next to patients or being in close contact with patients. But this adds to the urgency in Hong Kong to make sure that this remains true in the studies that are found because now, as you know, there are cases in schools, there are cases other places and we need to make sure that if there are other cases in schools, they aren’t cases that are randomly occurring but are cases which sat next to students who were sick. And the same goes for airplanes, if there are airplanes that transmitted someone who’s sick, we would want to be sure that it was people sitting next to that person and not the ventilation system in the aeroplane which was spreading the disease. We have no evidence of the latter right now but this is why studies are so important and why we reinforced our team to work with the very excellent teams in Hong Kong to find out what’s going on for sure.

Q. A couple of questions. I assume you are supportive of the mass quarantine that Singapore authorities have announced that they are starting today. Singapore today began ordering hundreds of people to stay at home and it’s being described as the world’s largest quarantine. They are making use of the Infectious Diseases Act which is the first time they’ve ever used it. So (a) are you in favour of measures like that? and (b) my second question is, when you were talking about the travel advisory, you seemed to stress there’s no new advice for the present. But are you expecting this might change after the meeting with industrialized countries today?

A. Dr David Heymann: The first is that WHO puts out recommendations on travel but it’s countries who make the final decision based on their legislation and their national laws. That’s why we’re meeting with countries today because other countries have the same concerns as Singapore does. And we’re trying to work with them to better understand the basis for their concerns. The recommendations of WHO are always evidence-based. That means that when we get evidence that suggests that we should be changing a policy, we move to change that policy. We’ve been meeting on a regular basis by telephone with many countries. Today we will bring all those countries together to discuss travel recommendations. And I will say what I would say every day, that we leave it open that if there is new evidence with which we can make a better policy or a different policy, we will do that and we will not hesitate to do it. So, our recommendations will be evidence-based and we do not make a recommendation if there’s no evidence to support that. This many times occurs in national contexts because there are rules or laws which require them to judge on the side of safety rather than on the side of non-safety, if you understand what I’m saying. So, yes there’s always a chance that WHO will change its recommendations and we will keep you posted if that should occur. Thank you.

Q. With Singapore, I presume that you are in favour of measures taken, such as those in Singapore – mass quarantine?

A. Dr David Heymann: Governments take a decision based on the conditions locally. If for some reason Singapore feels that they will not be able to trace all cases because there’s such great mobility in their populations that they must make restrictions on them, then that’s what they’ve decided to do. Our recommendation is that there be no restrictions at present. But that’s a global recommendation. And again, that’s being reconsidered on a daily basis and will be re-considered today at 2.30 pm in our conference call.

Q. The question about the two viruses having been, or two families of viruses having been associated with this disease or with this outbreak. You said it was not normal. if I’m not mistaken. Could you give us an idea of whether or not it’s possible for a single disease to be caused by two viruses or does it mean, or is it more likely that at least one of the samples might not be related to SARS?

A. Dr Klaus Stohr: Speaking as a scientist, we are looking at a very interesting and a fascinating situation. Looking from the point of infectious disease control, we are a bit puzzled because we are not only dealing apparently with one pathogen but with two. The reason why we believe that both pathogens should be given equal attention is that there is consistent finding of both pathogens in individual patients or of either of the pathogens in other patients. What we are seeing actually are three hypotheses. The first hypothesis is that one of the viruses, for instance the corona virus, causes the disease, and that might be a new corona virus. The second hypothesis is that the paramyxo viruses cause the disease and if that was the case, it’s certainly also a new paramyxo virus. The third hypothesis is, very obvious, is that these two pathogens have to come together to cause this very severe outbreak. One of the viruses, for instance the corona virus, is known to live in immune cells, cells which are important for the defence, for the body defence against infection. So what one could hypothesize is that this corona virus destroys or at least diminishes the immunity in the patient so that the second virus has practically an open door to go in and to sicken the patient beyond what this virus would be able to do normally.

Dr David Heymann: Let me just add to that: so, you know, the hypotheses, there could be a fourth. It is possible that both are common viruses: one found in all the patients, even though it's not causing disease, and the other will be the disease causing agent, so they could both be found but not be related in any way, just there by chance. So it's a very complicated issue that's being sorted out.

Q. In China, is the team in Beijing getting new figures on how many cases we have in China? Also, can they go to Guangdong or will they just remain in Beijing doing that kind of laboratory service?

A. Dr David Heymann: Yesterday the team in China had a question from the Government, and that was "why is WHO not putting on its web site the 305 cases that we reported?" The answer was because we only started recording cases from 1 February, and we don't know how many cases China had from 1 February on. That made the Chinese believe that they needed to go back and look at their data, and they've promised us they would do that and give us more information. Today that information has not come out yet. Our team has met with officials from Guangdong and from Beijing but the information is not yet available, but we have reason to believe that it will be made available and that there is very much interest in Beijing by the internatinoal press on these issues as well as by the press from outside Beijing.

Q. Is the team going to Guangdong?

A.Dr David Heymann: The team has not yet been invited to go to Guangdong and we don't know whether that invitation will be coming. Certainly our wish would be that the Government will permit us to work with them in all aspects of this outbreak.

Q. Do you think it's advisable for the team to go to Guangdong to help investigate what's going on? Did WHO request specifically that they should go to Guangdong?

A. Dr David Heymann: WHO has requested the Government to let the team work with them as best it possibly can, and we would hope that that would include working in Guangdong as well as working in Beijing.

Q. I have two questions. My first is that there is a lot of hypothesising about the first case of the outbreak, a lot of media reported that it was the Chinese businessman who came back from China who went to Hanoi who was the one who was dead in Hong Kong. Do you have any information about the first case? Secondly, can you clarify the route of transmission. Is it possible to have transmission by air?

A. Dr Julie Hall: We have quite a lot of information about the gentleman, what we are calling the "Hanoi index case", the Chinese American businessman who went to Hanoi, became unwell and was then transferred to hospital in Hong Kong. He was transferred in isolation and treated in isolation as well once he got to Hong Kong. The team in Hanoi are currently following up his travels prior to arriving in Hanoi. It seems that he travelled quite extensively prior to becoming unwell and prior to arrival in Viet Nam. Further details on that are currently being sought by our team so that we can follow his travels in the 2-3 weeks prior to him becoming unwell in a little more detail. Obviously, when somebody becomes unwell in one country, lives in another country, and is then transferred for care in a third country, it does take a while for all this detailed information to be put together.

Dr David Heymann: To date, in looking at every case that occurs, it has not been possible to say that there was not close contact with another patient, be it a family member of a hospital worker, a hospital worker, or one of the initial cases. Now that information comes in on a daily basis. If, and the minute we find, that there are cases which cannot be traced to close contact with another patient or another person at risk, we will then be very concerned that this might have become airborne. Airborne meaning that you would be at risk sitting where you are. The way it is today that we believe from the evidence we have, the only person at risk in this room would be Dr Stohr, who's sitting next to me. But if we find that you are at risk, we will immediately have to consider a whole series of new measures to recommend and the studies will have to intensify to find out how it's circulating wider than just by person to person contact.

Q. From what I understand from the end of last week, you were becoming more confident that you had this under control. But the data this week seems to show the opposite. How confident are you that you've got it under control? How concerned are you that it could be getting worse instead of better?

A. Dr David Heymann: When we made the global alert 10 days ago, our goal was to stop outbreaks occurring in other countries than Hong Kong and Viet Nam because of imported cases. We knew that Canada had had imported cases and had had local transmission within Canada. If you look at the global alert, it has brought in reports of disease from many different countries - 13 I believe is the latest count - and there has been no additional outbreaks set up in those countries. So the global containment exercise has been successful to date. The exercise of containing the disease in Viet Nam appears to have been successful, there has been a slowdown in new cases, hospital infection control has been strengthened in hospitals, and it appears that that outbreak has been contained in Viet Nam. In Singapore, where there were imported cases, there appears to now have been a closing in on contacts of patients, and we believe that the situation in Singapore is being controlled. In Hong Kong there is a very difficult situation and a different situation in that 10 hospitals are now involved. It is a very important exercise to contain the disease in these 10 hospitals. We also know that people have been in schools who have become sick, so there is where the efforts must be now intensified in addition to better understanding what is going on in China. So we have two countries in which we are very concerned now - Hong Kong - and in finding out more about what is going on in China because those are the two countries where we have less information and we are less sure that containment activities are being successful.

Q. For the incubation period of the disease, WHO said that it was 2-5 days or 2-7 days. In Hong Kong, however, the doctor was in close contact with the patient 11 or 12 days before. So people are now concerned whether we should play safe and extend the incubation period so that the virus won't spread even further. Do you have any information and recommendation on this?

A. Dr Klaus Stohr: Thank you. The incubation period is the period between the infection, when the patient gets in contact possibly with the pathogen, and when the first clinical signs occur. Now that is a very important period of time because it tells us presumably that during this period of time the person can start spreading the virus. The incubation period in Hanoi, from the data which has been collected during the first two weeks of the outbreak, the average incubation period is 4.5 days. The minimum incubation period is 2 days. The maximum incubation period is 7 days. Very similar data were forthcoming from Singapore, with a minimum 2 days, maximum 7 days. We are talking about a biological phenomenon and we cannot rule out that there have been slightly shorter or slightly longer incubation periods. However, we have also to realize that not every contact of a doctor with a patient must necessarily lead to an infection so even if there has already been contact between the doctor and the patient over a period of time perhaps the infection took only place 4 or 5 days after the contact began and the doctor started incubating. We are looking at a new disease. We are looking at possibly two different viruses so we really have to cautious in drawing generic and absolute conclusions. The data that we have are relatively firm 2 days to 7 days and we have to take more data and analyse it, and these data are going to be collected particularly from Hong Kong and particularly in Hanoi, but there will be analytical information perhaps like you describe but that has to be verified.

Q. Now we have 10 days of the global alert, can we say what of the number of cases known, what the mortality percentage is?

A. Dr Julie Hall: It has remained pretty static over the last 10 days, it's around about 4% of mortality rate. So it's quite low and we haven't seen any change in that mortality rate over the 10 days.

Q. In that case is it really such a horrible scurge that's menacing the world, because normally influenza has that kind of mortality rate doesn't it?

A. Dr David Heymann: I would differ I would say that this is not a low mortality rate, we want zero mortality rate. This is a 4% mortality in a disease for which we do not yet know the cause. So it's a very serious issue in having a 4% morality of a disease for which we don't yet know the cause and which is spreading throughout the world. 4% is a level of mortality that could be equivalent to other viral infections in many parts of the world. It's equivalent of what might be occurring with West Nile, it's probably more than what is happening with West Nile in North America. Dr Klaus Stohr: The low mortality rate is perhaps also being contributed to the enormous clinical efforts taken with those patients. In one hospital in Hong Kong there are more than 150 patients, almost 30 of whom are in intensive care. Quite a few of them are on ventilators, they would die without mechanical ventilation. The health system is burdened almost to the limit in quite a few of the hospitals and we have of course to look at the case mortality rate and morbidity but also at the burden on the public health system which is enormous. Dr David Heymann: And just to put one more thing in perspective. Suppose that there were two diseases occurring at the same time, SARS and a disease which causes the same symptoms but is less severe. It my be that this second less severe background disease, caused by another virus, would case a different case fatality rate. We can only begin to distinguish genuine SARS cases from other less severe diseases having similar initial symptoms when we have a diagnostic test. So we're still far from understanding everything.

Q. A technical question - if you do decide to change your travel advisory, will you let us know by email?

A. Mr Dick Thompson: On the web rather than email. A transcript of this press conference will be on the web this afternoon. Thank you.

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