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CDC Telebriefing Transcript

SARS: Update of U.S. SARS Case Count

April 4, 2003

DR. HUGHES: Good afternoon. I would like to welcome everyone to today's briefing on SARS. We welcome the opportunity to provide you with an update on this ongoing global microbial threat. This really represents a wake-up call to the United States and to other countries around the world regarding the challenges that emerging infectious diseases can pose, and we have seen clear evidence of the rapidity with which this particular illness has been disseminated around much of the world.

CDC is actively involved in an ongoing investigation that is led by the World Health Organization that is taking place in a number of countries around the world. We were able with WHO, today, to participate in an unprecedented satellite broadcast and webcast to provide updates on clinical features, epidemiologic investigations, laboratory results and the progress of the epidemic to clinicians and public health officials around the world.

We are working as hard as we can to get to the bottom of this problem and get it under control, and it's a real international effort in doing that. We express our sympathies to the many people around the world who are directly or indirectly affected by this emerging infectious disease.

Let me update you now on the U.S. case counts as of today. The current case count is 115. That is an increase of 15 from yesterday. These are reported from 29 states. There are no deaths among these suspect cases of SARS in the United States.

Forty-three of these 115 are or at some point were hospitalized. There are 27 that are currently hospitalized. Twenty-seven have had evidence of pneumonia in the course of their illness. Among the 115, 109 have traveled to SARS-affected areas and had direct exposure to this infection, four individuals are close contacts of patients ill with SARS who have traveled to affected areas, and two are health care workers who were exposed to one patient with SARS.

We are very encouraged that most people are recovering from this illness in the United States, and we are working very hard to understand this better so that we can keep everyone provided with the most current information.

On the international front, if you set aside the U.S. experience, today's report from WHO indicates that there are 2,222 cases. These are reported from 16 countries. There have been a total of 81 deaths, and the mortality rate is approximately 3.5 percent.

Among the many things that CDC is doing is working to alert outgoing travelers to SARS-affected areas, and we are continuing to meet planes returning from SARS-affected areas in providing disembarking passengers with health alert notices.

We have distributed now over 250,000 of these health alert notices and our quarantine officials and their colleagues have met over 1,000 flights today. We are distributing these health alert notices to travelers who are arriving directly or indirectly from Mainland China, including Hong Kong, from Vietnam and from Singapore.

Closer to home, we have about 18 multidisciplinary teams formed that are working very hard on this problem. It involves very much a multidisciplinary approach. We have approximately 20 people currently deployed to overseas locations to assist in this investigation. Some are returning and some additional ones are going. So this number is a bit of a moving target. We have a number of epidemiologic and laboratory surveys underway.

Let me provide you with a bit more of an update on the ongoing laboratory investigation. CDC is part of an international collaborating network of laboratories led by WHO. There are 12 laboratories and 10 companies participating in this network.

Evidence for this previously unrecognized Coronavirus has been found now in at least 10 laboratories, including the laboratories here at CDC. The preponderance of the evidence continues to mount and continues to favor an etiologic role or this previously unrecognized Coronavirus in the cause of SARS.

So far, in looking at specimens from the suspect cases in the United States, we now have evidence of infection with this agent in a total of four people, and we are working with the state health departments in the states where these people reside, so that they are provided with the information and they, in turn, will provide the clinicians and the patients with the information.

Now, let me give a little more detail on the extent of the laboratory evidence. We have cultured this Coronavirus from a total of four patients. We have electron microscopic evidence from two patients of this virus. We have PCR results--that is the Polymerase Chain Reaction, the amplification technique--where we find evidence of Coronaviral nucleic acid in 11 patients.

Looking at the antibody tests, of which we have two--an IFA test and Allose test--there is evidence for infection in a total of five patients. And from the standpoint of histopathology, looking through the microscope at tissue from deceased patients, we have seen evidence of an entity that the pathologist call diffuse alveolar damage, which is the pathologic correlate for the clinical syndrome of Acute Respiratory Distress Syndrome, which has appeared in patients with severe forms of SARS.

We have seen that evidence in a total of four specimens. Don't try to add those numbers up and get a grand total because some patients, in some cases, have more than one positive result.

So let me stop there and open it to questions. Let's take the first question from the telephone, please.

OPERATOR: Ladies and gentlemen, on the phone, if you wish to ask a question, press the one on your touch tone phone at this time.

And our first question comes from the line of Kathleen Donnehey from the Los Angeles Times. Please go ahead.

QUESTION: Good morning. Thanks for having this. Two quick questions. What's the typical recovery time of those who have SARS? And can you put this in some perspective, the typical mortality rate per year of influenza in the U.S.?

DR. HUGHES: Okay. Thank you very much for asking both those questions, particularly the latter, and let me take the latter first.

It's a surprise often to people to hear that every year on average there are about 20,000 deaths that occur in the United States that are attributable to influenza. We don't report a case fatality rate for influenza infections, and the reason that we don't in part reflects the fact that there are well recognized risk groups for severe outcome from influenza, the elderly, especially people in nursing homes, people with severe underlying disease. They will have a relatively high case fatality rate for influenza, certainly higher than 3.5 percent in severe outbreaks. But the average healthy person is not likely to die from influenza, so the mortality rate in that group would be much lower.

Now, in terms of recovery time, you're really asking about the natural history of this infection, and that data is really still being gathered. So I'm not able now to tell you what the average duration to recovery for those who recover are. And of course that's going to be influenced by a number of factors including age, underlying disease and treatment.

Yes, here in the room?

QUESTION: Like influenza, are there certain people that are more prone to catching SARS or having underlying conditions that might make them more susceptible to this?

DR. HUGHES: Yes. The question is, are there people at particular risk for SARS, and that's an excellent question, and the focus again of ongoing studies. There's no clear pattern so far in these cases. They are predominantly adults, many of them between 20 and 60 years in age. Some of them have underlying disease, but certainly not all. There probably are risk factors that relate to exposure, and there are probably also susceptibility factors for individuals that we certainly don't understand yet. But that's again--what is being illustrated here is the number of research questions that come up when you encounter a new disease, as we are doing.

Let's go back to the phones.

OPERATOR: Thank you. Our next question is from the line of Seth Borenstein from Knight-Ridder. Please go ahead.

QUESTION: Good afternoon. Thank you, Dr. Hughes, for doing this. A two-pronged question or two questions. First, on your evidence, the mounting evidence for the corona virus, on all those tests, can you give us a rough percentage of how many of these are U.S. cases and how many of these are cases where we are seeing a much more--a different acting, I think is the phrase that's been used, a virus, especially in Hong Kong and mainland China. In other words, are these tests mostly the U.S. version?

And then the second part is: when you look at the Canada, what is happening in Canada, is there perhaps a genetic or an ethnic explanation for why Canada seems to have a little harder time than the U.S.?

DR. HUGHES: Okay. How many U.S. cases have lab evidence of infection first. The answer to that is 4. But I will remind you now, as we think about how to interpret these tests, two weeks ago we didn't have a diagnostic test for this agent, and now we have one that's been developed, and for which validation is in progress. So keep that in mind as you hear about the results of the tests.

In terms of Canada, I think they were unfortunate. They got, early on in this, before the situation was recognized to be what it is, they had an individual who acquired the infection in Hong Kong, returned and infected some family members, and in turn some health care workers. This occurred at a time before the syndrome was really recognized and before aggressive infection control precautions were implemented. This shows how this infection can gain a foothold though, and I think we've been fortunate to date that it hasn't happened here, but with the nature of international travel, I think we all have to be prepared for the possibility that the people with severe cases could introduce this into the country, and it's the reason that we are doing all that we're doing to notify returning travelers and to notify the clinical community and the public health community so that surveillance is maintained and responses to this are very rapid.

Okay, here.

QUESTION: I have two questions. One relates to the two health care workers in the United States. I was wondering if you had any details on those cases. Was it a case of delayed diagnosis, or was a nebulizer used?

And my other question is about the effectiveness of infection control measures. I understand there are some reports that so-called negative pressure rooms in some cases haven't been tested and that they're not really negative pressure, or that the N-95s are not tight-fitting and therefore not effective.

DR. HUGHES: Okay. First of all, in terms of the issues related to the two health care workers, I actually don't know the details there. The state where those occurred would be the source of that. Those occurred quite a while ago.

The issue about infection control measures, how effective are they. The experience with this disease still suggests that the bulk of the transmission occurs by droplets which requires close contact over a distance of 3 to 6 feet. But there are some features that remind us to keep an open mind in terms of what role fomites, inanimate objects might play, or contaminated surfaces, or direct contact spread on hands might play. And those are the reasons that we have emphasized good personal hygiene and care in cleaning up body fluids in the environment, both in the health care and the home setting.

There's also the issue related to the possibility of airborne transmission. You're aware of some of these scenarios that are under investigation, the apartment building in Hong Kong being one example, where it's not possible to exclude airborne transmission, and that's the reason that the recommendations call for the N-95 respirators and negative pressure rooms when possible.

Now, you know, in any facility, the functioning of all aspects of the facility need to be closely monitored to know that they are functioning accurate.

Thank you. Back to the phone.

OPERATOR: Thank you. Our next question is from the line of Elizabeth Cohen from CNN. Please go ahead.

QUESTION: Hi, Dr. Hughes. Thanks for having this teleconference. Some of the folks in China with SARS have also been found to have Chlamydia. What do you think is the significance of that?

DR. HUGHES: The outbreak in Guangdong Province initially was reported based on some lab evidence that I don't know the details of, to be caused by Chlamydia and pneumonia. My impression is that they had a relatively few positive results for that. We certainly put Chlamydia and pneumonii on our long list of differential diagnostic possibilities when we first heard about the situation in Vietnam, Hong Kong and Canada. We, in our laboratories, have looked for evidence of Chlamydia and pneumonii infection in suspect cases, and so far have not found it.

Chlamydia and pneumonii I know I should say is a relatively common cause of atypical community acquired pneumonia, so it wouldn't be surprising to find it in some patients with that type of illness.

Yes, in the back of the room?

QUESTION: You talked about lab tests for which samples tested positive for corona virus. Have there been samples that tested negative?

DR. HUGHES: Yes, of course. The question about the negative results, since I've mentioned to you the positive results. There are negative results. I don't have numbers. For example though, when you think about antibody tests, what you really need to be able to interpret those and to say that something's negative is two antibody--two serum specimens collected 2 or 3 weeks apart. So any negative that we have now for the most part represents a single serum that's negative. So we wouldn't be--we're not in the position to say that that evaluation is complete. Part of our efforts now, working with the states, is to get paired serum specimens from patients so they can be tested.

Back to the phone.

OPERATOR: Thank you. Our next question come from the line of Marilyn Chase from Wall Street Journal. Please go ahead.

QUESTION: Yes. Hi, Dr. Hughes. Thank you also from me for having this briefing. I'd like to ask you to comment, sir, on a report by the Houston Chronicle that suggested today that they had obtained CDC quarantine records and found that airlines have routinely allowed obviously sick passengers to board international flights bound for the United States, and that Customs officials sometimes let them into the country. Would you please comment on this, sir, and share with us your thoughts on what the implications are for the adequacy of quarantine measures, both domestically and internationally?

DR. HUGHES: Let me make a couple of comments, and then call on Dr. Marty Cetron from our Division of Global Migration and Quarantine, who is also here.

First of all, I have not seen or heard that Houston report, so I can't really comment on that. I think it may be worth taking just a moment to remind everyone of the difference between isolation and quarantine. Isolation is a concept that applies to ill patients, and it's something that we do all the time in hospitals and other health care settings when the nature of the infection calls for that. Quarantine is a different approach that represents restriction of movement of people who may have been exposed to a transmissible condition, but are not themselves ill.

WHO has issued guidance for SARS affected areas, and they have called for screening of passengers for illness before they get on international flights. We've issued some guidance in terms of the approach--well, WHO has also issued guidance in terms of the approach to an ill passenger who's not recognized prior to departure but is recognized during the flight to have fever and a cough. So that guidance is available.

On arrival, as I mentioned, passengers are, if coming directly or indirectly from a SARS affected area they're provided with health alert notices.

Marty, do you want to expand a bit on that? This is Dr. Marty Cetron, who's Deputy Director of our Division of Global Migration and Quarantine.

DR. CETRON: Thanks, Dr. Hughes.

I'm not directly familiar with the article that you referred to either, but it wouldn't surprise me that there are occasions in which either an ill person or a person incubating a disease got on an airline and came into the United States. That would be a daunting task to try to detect every one of such cases.

More commonly though the speed and the volume of air travel poses a new challenge for us, and that is that the incubation period for most of these diseases is in the time frame of days, and the amount of time it takes to circumnavigate the globe these days is in a matter of hours, maybe 36 or 72 hours. So quite commonly, when we get calls about sick people, who are arriving after recent travel, first we'll grateful that the physician got a travel history and recognized that there's a potential link because that really helps. And secondly, the speed at which people can move is faster than the incubation of the disease. So most of the cases we hear about like that are actually occurring after the fact.

Someone tells you that there has been an exposure in the recent past, that people might have been exposed, and we go back and collect the passenger manifest and reconstruct the exposure experience to offer post-exposure preventive measures in the case of meningitis or other types of diseases. So it's the volume of travel and the speed of travel which makes the challenge at protecting the borders even more daunting today than it was 100 years ago.

QUESTION: I have a question about the incubation period, what is it? And also there were reports yesterday that some of the first people who came down with SARS had eaten wild game, and wanted to know what you have to say about that?

DR. HUGHES: Well, let me start with the incubation period. It looks like most typically it ranges from 2 to 7 days, but I think the range may be as short as one day on the low end, and up to 10 or maybe even 12 days on the high end. That will be refined better as more testing is done, and we are able to narrow down the focus to patients, the subset of these suspect cases who will actually be cases.

The wild game issue I actually have not heard before. Was that in the U.S. or in Asia or--

QUESTION: Asia.

DR. HUGHES: In Asia. I can't comment on that. I had not heard that. But, having said that, we don't know the source, the original source of this previously unrecognized virus.

There are a number of Coronaviruses that do infect animals, though. So it may well be, and it's the sequencing of the full virus that will tell us this. It may well be that there is an animal origin for this. So I'm interested actually to follow up and see what sort of wild game this is and what the evidence might be.

Back to the phone.

OPERATOR: Thank you. Our next question is from the line of Nancy Shute from U.S. News and World Report. Please go ahead.

QUESTION: Yes, Dr. Hughes, I'd like to hear more about why you think the cases in the United States appear to be less virulent. A couple of days ago when Dr. Gerberding talked to us, she seemed to feel that that was just a reporting artifact, that we're tracking less acute cases that may not be SARS, but earlier she has also talked about the fact that this might be a less-virulent strain here.

DR. HUGHES: Well, I don't think, I mean, we can't say much about virulence. Virulence refers to the organism. Certainly, you know, most diseases will have a spectrum of severity. There are obviously exceptions to that, rabies being the most dramatic example and Ebola being another one, where most people who are infected are severely ill. But most diseases have a broad spectrum.

We are using a very broad, very nonspecific, but quite sensitive surveillance case definition here to pick up these 115 suspect cases.
Now, having said that, though, why have we not seen one of these severely ill patients? I think we have been lucky, frankly. I mean, there is no better explanation at the moment, and we won't know until we get better information on risk factors, as they relate to exposure and individual susceptibility

Back to the phone or, I'm sorry, back to--here we go.

QUESTION: The CDC has issued the advisory to the four countries: Mainland China, Hong Kong, Vietnam, and Singapore. There are some U.S. companies now that are restricting the travel of their employees to all of Asia. Do you find that advisable or an overreaction?

DR. HUGHES: Well, you know, this is an outbreak in progress in evolution. We certainly haven't seen the end of this, and we have to stay tuned to the reporting. That's why we look every day about noon we go to the computer and look for the WHO update. Obviously, we are having additional conversations with them.

I mean, you have seen this spread geographically. It could certainly spread more geographically. We try to base our advice on the evidence in hand. We are certainly wary and concerned about the possibility that this illness could spread to other countries, and we wouldn't be surprised if it did.

Back to the phone.

OPERATOR: Our next question comes from the line of Jon Cohen from Science Magazine. Please go ahead.

QUESTION: I have two quick questions:

One is do you have any control data with the PCR showing that people who are healthy don't have evidence of this virus, and the other is what do you think of what Thailand is doing at the airport?

DR. HUGHES: Well, you will have to tell me exactly what Thailand is doing at the airport. I think I know, but go ahead.

QUESTION: As far as I understand it, according to the Bangkok Post, Thailand is screening all passengers who are arriving there and making all visitors wear masks for 14 days, and they're isolating anyone who shows signs, and they are doing stethoscope evaluation of people on arrival.

DR. HUGHES: Well, I hadn't heard about the stethoscope part, but they are looking for ill people, and we have heard that they are taking an approach that would involve home quarantine for people who have come in from SARS-affected areas who are not ill, so applying the quarantine approach to non-ill people. So we have heard that they are doing that.

In terms of PCR, yes, we have negative controls that we run, both for the PCR and for the serologic tests that we have done, and it looks like these tests are performing quite well, but it is early in their use.

Back to the room.

QUESTION: Thanks for the briefing.

I have a question. How many CDC people are involved in the WHO investigation in Guangdong Province, and is there any restriction for the investigation in there?

DR. HUGHES: The question refers to CDC involvement in the WHO-led investigation in Guangdong Province.

The WHO team arrived in Guangdong Province yesterday from Beijing. We have two CDC staff members who are members of that team--Dr. Rob Breiman, who is currently the leader of the team, and Dr. Jamie Maguire.

The team arrived yesterday. They had some initial meetings. We are optimistic that they will be able to review the data and give us a better sense of the current situation there, but we will need to stay tuned, and we will anticipate hearing from them as their investigation proceeds.

Back to the phone.

OPERATOR: Thank you. Our next question comes from the line of Helen Chickering NBC News. Please go ahead.

QUESTION: Yes, thank you for having the conference.

Can you give me or elaborate more on the status of a possible diagnostic test. And my second question, do you see this as a fire drill for bioterrorism? Specifically, are you evaluating your infection detection and control abilities in local hospitals?

DR. HUGHES: This is a fire drill for a number of things. It is a fire drill for an unexpected, severe acute respiratory disease. The one of those that we know is going to occur one day is the next worldwide epidemic or pandemic of influenza. So those of you who have been interested in following influenza preparedness in the past ought to pay very close attention to this. This has many similarities to the way the next influenza pandemic might begin.

Now, having said that, I am sorry, I have forgotten--well, let me, in terms of bioterrorism. Yes, I mean, we are operating through our Emergency Operations Center. That center was activated by Dr. Julie Gerberding, our director, back on March 14th, and it's been operating around the clock ever since.

We're using that now. If we have a bioterrorism attack, we will be using that emergency operation center and doing many of the same things that we're doing now, operating through multidisciplinary, headquarters-based and field teams.

So this a drill. We are building on our experience in dealing with anthrax, on the one hand, and also on our experience in dealing with West Nile encephalitis last summer as it swept across the country. And I would just remind everybody we're paying close attention to what's going on with West Nile Virus right now because, as things warm up, we're going to come back into West Nile transmission season before too long.

Now, you did ask an original question, and I admit I have totally forgotten that now, and you may have lost your opportunity. I apologize.

Back to the room.

QUESTION: I think she was saying what's the status on the diagnostic tests. And I wanted to add to that. I wanted to ask whether all of the U.S. cases are being tested now or they will be, and then is there anything promising regarding treatment candidates or options, and then I was wondering if Dr. Cetron can give us an update on the guidelines or measures being worked out with the airline association.

DR. HUGHES: Good. Let me take the first couple and then have Marty come back up.

There are several diagnostic tests that look promising. There is the ELISA test for antibody, there's the Indirect Fluorescent Antibody--or IFA--test, again, for antibody, and then there's a PCR assay that look like they have potential to be useful.

We will be collecting and testing as many specimens as we can acquire from suspect cases, from health care workers exposed to them, from household contacts, and from healthy controls over time to further validate them.

We are going to be trying very soon to transfer some of these tests to state public health laboratories through the Laboratory Response Network so we can get the diagnostics, such as they are at the moment, closer to where the illnesses are occurring. So that's a high priority.

In terms of therapy, there is a collaborative effort right now between CDC and NIH and the Department of Defense, the USAMRIID group. They have the virus, and they're working with NIH and us to test it against a broad range of antivirals that are either on the market or are in development.

The clinical experience in some people's view suggests that Ribavirin has some effect. We're anxious to see how Ribavirin actually looks in cell culture in the test tube against this virus, and we don't have that data yet.

There are some studies being planned to assess the value of Ribavirin, and certainly if we find other candidate drugs, we'll be very interested in trying to set up studies to evaluate them.

So, having said that, Marty, do you want to take the other question?

DR. CETRON: Thank you for the question.

This outbreak has given us a tremendous opportunity to strengthen our partnerships with the airline industry. In fact, we have a number of guidelines, interim guidelines, that are already posted, and we continue to work with the industry on new possibilities. We are exploring the development of an in-flight educational video that would run for passengers and provide information about SARS.

We are also exploring with them the possibility of more efficient means of collecting passenger manifest data to allow more swift follow-up of exposed contacts if there happens to be an index case on the plane, and we are exploring with them further guidance and revision to the guidance on how to manage an ill passenger that might have suspect SARS in transit.

So all of those things are ongoing, and we are very optimistic about the outcome of them.

DR. HUGHES: Back to the telephone.

OPERATOR: Thank you. Our next question comes from the line of John Loriman from Bloomberg News. Please go ahead.

QUESTION: Hi. Thanks for taking my question.

I would like to hear a little bit more--did you say there were 115 patients in the United States right now; is that right?

DR. HUGHES: Yes, there 115 suspect cases. That is today's count.

QUESTION: Did you say only six of them were transmitted here in the United States?

DR. HUGHES: There were two health care workers who were exposed to one patient and then there were four family contacts, family members of cases. Yes, so a total of six. The other 109 traveled to SARS-affected areas themselves.

Back to the room.

QUESTION: Among the 115 U.S. cases, how many of those occur within the Asian population, and is there a greater risk of encountering SARS within a Chinatown of a U.S. major city?

DR. HUGHES: Well, we certainly don't have any evidence of any of the U.S. cases being acquired in a Chinatown area of a U.S. city. In terms of are there genetic determinants of susceptibility, which I think is sort of where your question is going, that's unknown. We don't have--by no means do we have complete race and ethnicity data on these patients. That will be coming in. But you have to remember that to be able to interpret any data like that, you'd have to have the denominator data in terms of the proportions of folks that actually travel to these affected areas.

So genetic factors associated with susceptibility is one of the many things that will be looked at as this continues.

Okay, back to the phone.

OPERATOR: Thank you. Our next question is from the line of Lynn Adrian from ABC. Please go ahead.

QUESTION: Yes, thank you for taking my call. Could you give me the name again of the CDC investigator who's leading the team in China, and also can you comment on how much cooperation that you are now getting from the Chinese Government?

DR. HUGHES: Dr. Rob Breiman, B-r-e-i-m-a-n, is the person heading the WHO team in Guangdong Province. He is a CDC employee.

The cooperation has improved dramatically. We were able to have the team go to Guangdong. And I should tell you that Secretary Tommy Thompson last night spoke by telephone at length with the--his counterpart, the Minister of Health in China. And they discussed this experience in detail. So I am optimistic that in part as a result of that conversation, that cooperation will be there as the team continues its work.

So back to the room.

QUESTION: I had a question about the WHO investigator who died of SARS. If I understood correctly, you're saying people are more susceptible if they had co-morbidities, if they were older and had other illnesses. Was he a completely healthy person?

DR. HUGHES: He was a vigorous, healthy person as far as I know. So, no, I didn't--I don't think--I didn't mean to say that--I was talking about influenza, and clearly there, you know, it's very clear that people with underlying disease are more susceptible to severe outcome. It's too early to know here, but a number of the people who have had severe illnesses and died have been healthy adults, relatively young adults without a lot of underlying disease.

QUESTION: And my other question, you mentioned--just getting back to the health care worker issue. What state were those two health care workers from?

DR. HUGHES: We let the states report their own data.

QUESTION: Okay, thank you.

DR. HUGHES: Back to the phone.

OPERATOR: Thank you. Our next question is from Tina Heffman from St. Louis Post Dispatch. Please go ahead.

QUESTION: Hi, Dr. Hughes. I was wondering--I spoke to officials from the World Health Organization this morning. They said that they don't think that this infection has the ability to become a pandemic. Would you say that there's enough data to support that conclusion, or do you think that there is that potential?

DR. HUGHES: I think we had better all keep an open mind here. We've seen it spread very dramatically and very rapidly to a number of countries, and there are measures in place now that I hope will slow it down and eventually stop it. But I'm not going to be complacent. We haven't--we're not totally on top of this by any means, and I don't predict that we--we have to stay tuned and treat this as the urgent global public health threat that it is.

Back to the room. I'm being told back to the phone and then we'll come here.

OPERATOR: Thank you. Our next phone question comes from the line of Maggie Fox from Reuters. Please go ahead.

QUESTION: Hi, Dr. Hughes. I have a couple quick questions. No. 1, can you talk about the possibility that Chlamydia could be the co-infection that you've sometimes been looking for, and can you characterize the Chlamydia microbe for us a little bit?

And second, can you comment on a report we got from one of the Chinese doctors, who said he's had some success of treating patients with serum from other patients?

DR. HUGHES: Well, let me take the second first. The use of serum or plasma obtained from patients who have survived this illness and made antibodies to the virus, we heard this morning--actually I had not heard this until this morning on the WHO/CDC satellite broadcast that I mentioned. One of the physicians from Hong Kong, Dr. Sung [ph], reported on their experience in treating these patients. And they have used some antibody obtained from surviving patients' serum to treat a few people. I didn't catch exactly the number. And he had some evidence to suggest that there might have been some response there. So if you want more on that, I would advise everybody to go and look at that webcast that would be available and you could see exactly what he said.

That's another item for the short-term research agenda, needless to say.

Speaking of that, before I answer Chlamydia, that actually reminds me of one other thing I wanted to say earlier. Yesterday, PHARMA, the Pharmaceutical Manufacturers Association of America, convened a large teleconference involving senior representatives from the pharmaceutical industry and people here, people at FDA, people at NIH and people at DOD, to talk about issues related to drug development and vaccine development. So I mention that just so you know that there are a lot of people across a range of disciplines engaged in thinking about and evaluating potential therapies, as well as taking approaches to vaccine development.

Now, in terms of the, the role of Chlamydia and pneumonii as maybe playing some role as a co-infection, in the patients that we've looked at, we've not found evidence of Chlamydia and pneumonii infection, it is an organism though that can cause a typical community acquiring pneumonia. I'm not aware really in any of the other countries, other than the initial reports from China, I'm not aware of it showing up with any significant frequency. So I don't think it's likely to be playing a role here.

Now, back here.

QUESTION: Dr. Hughes, if the old adage is true that there's nothing new under the sun, what can you tell us about the origins of SARS and why it's just now coming to light and spreading so rapidly? And are you giving any advice to average citizens to protect themselves from contracting this other than close contact with an exposed or infected person?

DR. HUGHES: Let me seize the opportunity here to call a recently released report to your attention, and this is the Institute of Medicine report that was released about 2-1/2 weeks ago no, Microbial Threats to Health: Emergence, Detection and Response. It's uncanny to read this and to look at their comments about what the future holds in terms of infectious disease challenges and what needs to be done to strengthen the capacity of the country and the world to deal with these things.

It may not be brand new. It probably isn't. Just as hantavirus pulmonary syndrome back in 1993, that unusual infection that was recognized in the Southwestern part of the United States that was thought initially to be brand new, caused by a previously unrecognized hantavirus. But doing studies, looking back, sporadic cases of that were found back 20 years or more before 1993, and there's clear evidence that that virus has been present in deer mice, the reservoir for probably thousands of years.

So, new to people? Yes. New to the world? No. And that may well be what we find here. When we get that sequence of the virus, we'll have a better indication of what the original source might have been, and that will allow efforts to focus on potential reservoirs.

In terms of people, what they can do to minimize their risk, so far, if you haven't--in the U.S. if you haven't traveled to an infected area, or you haven't been exposed to an ill family member or patient who has, there is no evidence that you are at risk at all. But I would take this opportunity to remind everybody of the importance of personal hygiene, and as with many infections, and certainly for this one, the importance of hand hygiene and appropriate hand washing, can't be over-emphasized. And we'd like to remind everybody, if they have a respiratory infection, even though it is in no way related to this, it is appropriate to not cough and sneeze on other people and to observe good hygienic standards while ill.

Okay, thank you. Back to the phone.

OPERATOR: Thank you. Our next question comes from the line of Joanne Silbener [ph] from National Public Radio. Please go ahead.

QUESTION: Yes. Dr. Hughes, thanks for taking these questions. Looking at the CDC case definition, it doesn't--it is from, but it doesn't included people who haven't had contact with someone with SARS. Couldn't that mean that you're leaving out some people? How will you know if people who haven't had direct contact, they've had a more distant contact, how will you know if they are getting sick?

QUESTION: Well, that's actually an excellent question and one that we're talking with states and local public health officials about. Casting the net a bit more broadly, I mean everyone now, because of concerns about bioterrorism, is alert to clusters of cases of severe or unexplained acute respiratory disease. So everybody is sensitized. And we'll certainly be testing--if such clusters are encountered, we'll certainly be testing them for evidence of infection with this virus.

You're right that we can't totally close our mind to that possibility, but there's no evidence for that so far.

I'm getting an indication we'll take one more question, and we'll take that from the phone.

OPERATOR: Thank you. Our last question comes from the line of Marian McKenna from Atlanta Journal Constitution. Please go ahead.

QUESTION: Hi, thanks for doing this. I have two questions, and I'm afraid they're totally unrelated. The first is returning to the issue of the diagnostic test. Is there any possibility that you're going to be able to at some point to develop a nucleic acid test for SARS, for the agent of SARS? Do you have enough of the sequence of the corona virus yet to look at it just like that?

And then I'll hold my second question till you answer that.

DR. HUGHES: Okay, Marian, thanks. Yeah, actually we already have one that looks like it works pretty well. It needs more validation. But it's one of those tests that we hope within a week or so to be able to transfer to the state public health laboratories participating in the laboratory response networks. Some work needs to be done to get it ready to be transferred, but, yes, the bottom line answer is yes. PCR looks promising. That could be done on tissue as well as throat swabs or nasopharyngeal swabs.

So go ahead. We'll give you the final question.

QUESTION: Okay. Thanks so much. So my final question is, Health Canada is beginning, in certain limited cases in some of the hospitals in Toronto, to be able to derive an attack rate for SARS. So my question is: do you have enough data yet in any of the clusters that have been looked at epidemiologically to be able to derive any kind of an attack rate? And more broadly, is it going to be possible, at any point, do you think, to derive a broader attack rate, or to be able to determine what the denominator of exposed people has been?

QUESTION: Yes. Thank you for your call for some epidemiologic rigor here in the investigation. I think you're right on.

In terms of attack rates, that's the number ill over the number exposed, gives you an attack rate. We are looking right now, in the course of several ongoing--or in surveys that are actually about to start--to look, for example, at a cohort of Americans who stayed in the Metropole Hotel, you remember, which was the source of a lot of this initial geographic dissemination. There was a period of time where an index case stayed there over 24, 36 hours. We've gotten now the list of Americans who were in the hotel at that time, and we're working with state colleagues to follow up on those people. So we would be able to get, I hope in the end, an estimate of the number of those people who were infected compared to the total number that were there. So that would give you an attack rate.

We're doing similar things in follow up to airplane exposure. And we'll be doing surveys of household contacts too, so there will eventually be I think an estimate of the secondary attack rate in households.

So let me stop there. Thank you all very much for your interest and attention, and wish everybody a good weekend.

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