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CDC Telebriefing Transcript

Update on Severe Acute Respiratory Syndrome (SARS)

May 15, 2003

DR. GERBERDING: Good afternoon. I'm here today to provide an update on SARS. We are continuing to receive reports of new cases of SARS in China, Hong Kong, and--Mainland China, Taiwan and Hong Kong. The WHO is reporting 7,564 cases of SARS as of yesterday. The death rate is approximately 8 percent overall, but as we've discussed in several publications, we know that death rate may change over time.

In the United States, we have a total of 64 probable cases of SARS. Sixty-two of those are travel related, and we have 281 suspect cases. There's some good news here in the United States, and that is in the first 15 days of May, we've had only one probable case reported so far.

Of course, we may see more probable cases, but that compares to the month of April, where we had a total of 32 probable cases of SARS reported in the U.S., and that's an indication, I think, that international travel advisories, and the other steps that are being taken in the countries were SARS is ongoing, seems to be working and that we are importing fewer cases of SARS into the country. So that's good news and I think allows us to be cautiously optimistic.

Of course, it only takes one patient in an infectious state to slip through the cracks, so we have to continue to retain our vigilance on this front.

We have sent out more than a million health alert notices. This is an unprecedented accomplishment in a very short period of time by the CDC folks who are at our quarantine field station at the points of entry and also due in large part to the collaboration that we've established with customs officials and others in the Department of Homeland Security. I think that also is a very important component of the success of our containment efforts so far.

Today, CDC is reporting, in the Morbidity and Mortality Weekly Report, MMWR, an update of investigations that have involved collaboration with Canadian health officials, as well as members of the CDC, looking into the spread of SARS in hospital settings, particularly hospital settings in Toronto, Canada.

This is an investigation that has evaluated a cluster of health care workers who became infected while caring for an infectious index patient who had had a prolonged hospitalization. The health care workers involved in this were really engaged in state-of-the-art infection-control practices.

The facility was using all of the recommended infection-control precautions, and the investigation was conducted, in part, to determine what could explain the transmission in the context of what would otherwise be deemed a very highly compliant set of health care personnel and a very compliant hospital.

The investigation evaluated 11 individuals with suspect, probable or possible SARS who had been taking care of a patient who had subjectively developed more severe respiratory illness during the hospitalization and required an invasive lung procedure, specifically intubation. In addition, the patient was on a type of ventilation that may have allowed for aerosolization of respiratory secretions into the room.

So there were opportunities for the SARS virus to become airborne in this context, and one of the hypotheses that needed to be evaluated was whether or not there was adequate protection against airborne spread. There are other hypotheses. Not all of these have been tested or ruled-out at this point in time.

I think the main findings from the investigation so far were that there is clear indication that this was transmission from the source patient to the involved health care workers, that it is imperative that we practice extreme vigilance in infection control precautions, that airborne contacts and standard precautions are appropriate in situations where patients with SARS are housed and that the droplet precautions that have been the primary focus need to be continue as well.

We know that most patients with SARS acquire their infections through close face-to-face contact, but there are obvious examples where we can't rule out the possibility of aerosol or airborne transmission, and so in health care settings we are emphasizing the extreme importance of vigilance to all levels of airborne protection.

That includes for the health care workers, masks that fit tightly to the face. In the United States, that means masks that our National Institute of Occupational Safety and Health has registered as being N95 or more efficient, N95 respirators, and that the respirators be fit-tested so that they form a good seal around the nose and face of the person wearing the mask.

In addition, we recommend that patients with SARS in hospital settings be in rooms that have the appropriate level of ventilation to assure that there is no escape of the air from the room into the rest of the health care environment and that there is an adequate filtration and air exchange system in place.

Additional common-sense measures included in these precautions are masks and goggles to cover the other mucous membranes and face, gloving, gowns and appropriate putting on the equipment before contact and the appropriate measures taking off the equipment and decontamination of particularly the hands when that's completed.

So we are still learning about what's working and what's not working for infection control, but these experiences in Canada I think have again taught us some lessons that we'll be transmitting here in the United States.

We are looking at the adequacy of our guidelines for preventing transmission of SARS during procedures that involve aerosol generation. That would be the kinds of airway manipulations that many very ill SARS patients have, and if additional protection is indicated, our Advisory Committees will be assisting us in drafting those recommendations and then disseminating them throughout the health care delivery system.

The last important piece of information today is that we have an additional country, Vietnam, who has been more than 30 days after the onset of the last probable SARS patient, and so Vietnam is being taken off of the list of countries for which we are issuing health alert status for travelers or travel alert status.

What this really means is that there's no ongoing transmission in Vietnam and more than 30 days have gone since the onset of the last case, where there was a community spread. So what we have in place now, today, are travel alerts for Toronto, Canada, which may soon go off the alert list as well, and Singapore, which is equally on track for coming off the alerting list.

Advisories remain in place for China, for Hong Kong and for Taiwan, and these are countries that have ongoing community transmission, and we are continuing to recommend that people not go there unless they have essential business.

Alerts and advisories pertain to outbound passengers and its information that tells people what to be alert for when they travel to these countries. So, we also have guidance for inbound passengers.

First of all, you're familiar with the health alert notice that simply advises people that if they've been in a SARS-affected area to seek medical attention, if they get sick within ten days of their return. But in addition, we have guidance that addresses some of the concerns that colleges and businesses and others have had about a potential risk from people coming in to assemblies or gatherings or courses or graduation ceremonies, et cetera.

The CDC has received a great deal of input into our guidance and earlier this week we posted on the Internet and send out to various entities recommendations on at least interim recommendations that simply state that at this time we do not recommend that meetings or assemblies be postponed or canceled because of concerns about travelers from SARS areas, and that we are not recommending quarantine of anyone coming in from a SARS area, and so that we feel that not only is the international community stepping up to the plate to prevent exportation of SARS into other countries but our system here of travel alerts and advisories seems to be working.

As I mentioned, the fact that we've had only one probable case of SARS diagnosed in the United States in the last fifteen days is suggestive that the system is working the way we intend it to.

We have included in our advice some additional steps that people may wish to take as extra margins of safety if there are ongoing concerns about exposure to SARS during meetings. But I think the message is that we want an open door here. We want an open door that is based on common sense and the evidence that we have available to us, and we think that right now, the situation in the United States is sufficiently contained, and that the travel situation and risk is sufficiently low that these are the appropriate steps for our visitors.

So let me stop and take some questions at this point in time. May I take the first question from the room, please.

QUESTION: Thanks, Dr. Gerberding. Betsy McKay from the Wall Street Journal. I have two questions, if I might. One is that after 96 tests, I believe, still only six people have been confirmed in the U.S. to have SARS.

I'm wondering if that surprises you and if it suggests that the prevalence of the disease here is not as great as one might have suspected, or was suspected at first.

The second question is I just wonder if you could comment on what clues research that you're doing into the virus, and investigation of patients in the U.S., might be yielding right now about the virulence of SARS in the U.S. versus other countries. In other words, are you learning anything about why the disease is milder, seems to be milder? Thanks.

DR. GERBERDING: We have many investigations that are currently ongoing and some of these questions can only be answered with time. I'm not surprised that we have a relatively small proportion of our probable cases showing evidence of virus infection or coronavirus infection, and I'm even less surprised that our suspect cases are showing evidence of coronavirus infection, because we knew from the beginning that we were casting a wide net, and so we have over-included people unlikely to have true coronavirus infection to be on the safe side and assure that everybody who needed containment was properly isolated.

We also have a lot to learn about the sensitivity of the test that we're using and I think that's one of the ongoing studies that we need information from, and that is what is the probability of getting a positive test result if the patient has coronavirus infection, and until many, many samples are conducted, we are not going to have an accurate answer to that question.

Virulence of the coronavirus is also a subject of great, intense investigation. I think we recognize that the huge spectrum of illness in all countries, most patients in all countries have very mild illness, and recover, and probably wouldn't require hospitalization if they had other means of being isolated.

So the fact that of our SARS patients here, we've had a very few with the severe pneumonia, it may simply be the spectrum of illness that, you know, the probability is low enough that we wouldn't have picked up the people at the far end of the bell-shaped curve, but we also are open to other explanations, including the susceptibility of the people who have acquired the infection. If affected people have other medical conditions, they may be more likely to have the severe form of the illness, and many of the people in our country are travelers who are, in general, relatively healthy and may be at lower risk for the severe complications.

So we can't ascribe anything at this point to the virulence of the virus until we know more about the strains and more about the individual patients. But those studies are ongoing.

Let me take a telephone question, please.

MODERATOR: Thank you. But first a reminder to the phone lines. Please press one now if you have a question. We'll go to the line of Seth Bornstein with Knight Ridder. Please go ahead.

QUESTION: Yes; thank you, Dr. Gerberding. Looking at what you found with the health care workers in Canada, I have two questions.

First, if there any explanation why, given that they had, as you say, state-of-the-art infection control, why we didn't have something similar spread to health care workers in the United States? Is there any difference between the U.S. and Canada precautions?

And two is can you give us a status report on how much U.S. hospitals, if they have enough of the zero, the negative pressure isolation rooms, and all the other infection control equipment that you would need if this were to come here in the numbers that we've seen elsewhere?

DR. GERBERDING: One of the most striking things about the situation in Canada is that the source patient of this particular cluster of cases was extremely ill and was in the hospital, in respiratory care, for a very long period of time. That patient also had a number of procedures and the kind of ventilation that could have easily aerosolized the virus or created more droplets, and more opportunities for contamination, either of the air, the environment or the individual health care workers in close face-to-face contact.

We haven't had a patient like that in this country. So I don't think we can ascribe the difference solely to differences in infection controls. It's very important to consider that we have not had a patient who appears to be as ill as this particular patient was.

You know, in this country we have a very sophisticated infection control network, and because of concerns in past years about tuberculosis, multidrug-resistant tuberculosis, and more recently concerns about preparedness for smallpox, hospitals have I think created additional rooms and venues for sustaining airborne protection.

Of course we don't have large numbers of those rooms in any given facility and you sometimes have to look at a more regional perspective to see what the total capacity is. But even if we didn't have enough high ventilation, individual rooms for patients, there are still other steps that can be taken in an emergency, if we had a large volume exposure. These measures have been successful in other parts of the world, such as Singapore, where they've been able to contain their epidemic, and those measures consist of cohorting patients with SARS on a given ward of the hospital and separating them geographically from uninfected patients.

So I think we can scale up our response if we should be in a situation where we need that extra surge capacity, but it is something to think about and certainly part of our overall preparedness effort. As we look at pandemic planning for any problem, the capacity to be able to provide for care and treatment is one of the weak links in the system and that's why Secretary Thompson and the President's budget includes additional millions of dollars in the next fiscal year appropriations, a proposal to deal with surge capacity for preparedness for these kinds of infection threats.

Let me take a question from the room, please.

QUESTION: Hi. David Wahlberg from the Atlanta Journal-Constitution. Could you give us a few more details on the status of the government PCR test for SARS and when it might be available to ship out to the States for wider use.

DR. GERBERDING: The CDC's PCR test is a test that we are using here at CDC and we are learning from it as we go. It is not just a single step test. It actually looks for three different components of the virus that we're looking at and so that makes it more specific than if we were just looking for a single section of the coronavirus.

It is a test that is brand new. We made it in our own labs and so we have, you know, to really validate its utility. As with any PCR test, there is always a problem of a false-positive because they are so sensitive to the small amounts of DNA that could be a contaminant or carried over in the process of obtaining specimens, or transferring specimens, that we have to always make sure that we have the appropriate control measures.

One of the reasons that it's taking us a while to scale this particular test up is that we do need to have both positive and negative control samples so we can determine whether the test is performing the way it should.

It would be dangerous to send coronavirus out to every single lab in the country that needed a positive control, if we could avoid it. So what we've done instead is to manufacture genetic sequences that contain pieces of this particular virus and we can use those pieces as positive controls instead of the whole virus, and it takes a while to scale that production up and to verify that we are creating what we think we're creating, and that we are, you know, getting the kinds of accuracy from these tests that we want. So it's a work in progress, and I think, you know, we're using it in house here. We would like to make it available as quickly as possible but we want to make sure that we've dotted every I and crossed every t, and also that when the test is put out for general use in the public health system, that both the people who are using the test as well as the clinicians and patients who are potentially learning about test results have a full understanding of exactly what a result means and that should take some time.

I'll take a question from the telephone, please.

MODERATOR: Thank you. That will come from Elizabeth Cohen with CNN. Please go ahead.

QUESTION: Hi, Dr. Gerberding. I was wondering when all those I's are dotted and T's are crossed, and you have the test that you want, is the long-term goal to test all of the 200 and whatever possible cases to see if they have antibodies, if they really did have SARS?

DR. GERBERDING: Ideally if we had specimens on all of the patients included in the suspect and probable case list, we would like to have complete and comprehensive testing on all of them. Unfortunately on many of them we don't have the initial specimen from when the patient originally became ill. And for many of them we don't have the final specimens that we need for the antibody test to be sure that it's either finally positive or truly negative.

So that would be our goal, but realistically we're not going to have a complete set of information on every patient. That just never really happens in this kind of a public health situation.

We certainly also need to do testing on people that we don't think have SARS, so that we have some negative controls. And we are doing a lot of testing on people who are exposed, but not necessarily infected. So we will have a spectrum of samples that will help us again understand more reliably the accuracy of the panel of tests that we're developing.

May I have another telephone question, please?

MODERATOR: Thank you. That will come from Yanik Dumont with CBC News, Canada. Go ahead, please.

DR. GERBERDING: I don't hear your voice.

MODERATOR: Okay. I'm sorry, his line has disconnected.

DR. GERBERDING: I'll take another telephone question, then.

MODERATOR: And that will come from Roger Mezger with the Cleveland Plain Dealer. Please go ahead.

QUESTION: Yes, Dr. Gerberding. An announcement came out this morning about the satellite broadcast webcast scheduled next week on public health preparedness for SARS. And it says that it will provide information to state and local health departments on isolation and quarantine. Is the CDC at that time going to ask state and local health departments that prepare plans for dealing with SARS like they did with smallpox?

DR. GERBERDING: The CDC has been acting in state and local health departments to deal with planning for communicable diseases for quite some time. But the specific broadcast is targeted toward making sure that people can learn from the lessons that we've learned from Canada and other situations, in that we have been able to translate that experience into sensible steps that could be taken locally.

This is all based on an observation that's been made several times over the last several weeks. And that is that if you're going to be effective at containment, you have to act boldly and quickly when you first discover that you have a chain of transmission established. And the best way to be sure that this can happen at the local level where the officials have the jurisdiction to make those decisions quickly is to plan ahead.

And so that's what we're asking people to do. Not only know what they would do from a practical standpoint, but also understand what their legal authorities are and how to fairly exercise them to accomplish their goal, but also to protect the rights of the individuals who are affected by this.

Let me take another telephone question.
MODERATOR: Thank you. We'll move on to the line of Tonya Tellago with the Toronto Star. Go ahead, please.

QUESTION: Hi. In Toronto health care workers have been using N95 masks all along. Is there anything more we can be doing here in Toronto? We've started to use the space shields and the double gloves, the double gowns, and everything else. Are you saying that we should possibly be using biohazard suits with dealing with some of these SARS super-spreaders?

DR. GERBERDING: No, I'm certainly not saying that. I think that this investigation is still ongoing and there may be additional information to report as some of the environment evaluation and other more detailed evaluation results become available.

But I think the first step is to look at whether or not what's being done is being done in the best possible way. And I think that there were examples cited in the MMWR report where individual health care workers recognized that they may have been wearing masks, but they were not in fact technically N95-certified masks. And more importantly they were not actually fitted to their face, so that there was concern about a face seal.

One individual specifically described feeling the air moving out around the nose. So as you know, a mask is only as good as the seal. And if there are issues about the way the masks are fitting, that would be the very first step to take to try to improve the level of protection.

There will be other information available as we go forward, and at least from the U.S. perspective we are certainly going to present this experience to our expert consultants and make sure that we're doing everything possible to protect health care workers.

We are not moving in the direction of a full containment suit at this point, however.

Is there another question from here in the room?

QUESTION: Dr. Gerberding, David Leukowitz with Fox News Channel. Last week you talked about, I think it was 32 companies that had requested information from the CDC, and a smaller number had been approved to get the coronavirus, so they could provide new update on that.

DR. GERBERDING: Yes, so far we've received 129 requests for various components of the coronavirus, from commercial entities and academic institutions that are involved in research protocols.

To date we have shipped RNA to 40 locations, and we have shipped virus to 24 locations, and we have shipped antigen to six locations. The other applications are in review, and when individuals successfully complete the biomedical licensing agreement, we are working hard to expedite transfer of the appropriate reagents to them, as well.

A telephone question, please.

MODERATOR: That will come from Anita Manning with USA Today. Please go ahead.

QUESTION: Hi, Dr. Gerberding.

Under the Lessons Learned categories, I'm thinking about how our emergency department waiting rooms are right now in hospitals where people come in from all over with all kinds of things and they are all mixed together. Are there any changes based on what we've learned from our friends in Toronto and elsewhere? Any chances planned for hospitals in that way where CDC might ask people to separate people who have fevers or anything like that?

DR. GERBERDING: You know, it's not widely appreciated but for many, many years, CDC has had infection-control guidances for places like emergency rooms or urgent care centers where particularly coughing patients with fever are advised to either wear a mask so they don't disperse their droplets into the environment and pose a risk to others, and better yet that they be placed in a properly ventilated room.

Again, this recommendation was highlighted when we were concerned about tuberculosis transmission in health care settings. And so there is a generic recommendation that emergency rooms have at least one isolation area for the management of such patients if engineering for that is feasible in a given institution.

So following the recognition that tuberculosis was a problem in many emergency room facilities, there was a great increase in the capacity to manage patients with potential airborne illnesses in those environments.

So we emphasized those steps again with SARS when we put out guidance for infection control professionals and clinicians. And we are aware of creative and additional steps that have been taken in many emergency rooms, including adding questions to the triage of individuals about their travel history or putting up posters or special signs reminding people to inform the clinicians that they have a travel history or have any additional reasons to be suspicious about SARS.

So the concept is important. Getting 100 percent compliance is not always easy. But I think people at the moment are extremely motivated, and we've seen very great interest in making this happen.

May I take a telephone question please?

MODERATOR: We have a question from Maggie Fox with Reuters. Go ahead, please.

QUESTION: Hi. Thanks very much. I was wondering if you could expand on the MMWR description of the process of intubating this index patient in Toronto. What are some of the different types of ventilation that could cause these particles to become aerosolized?

DR. GERBERDING: Well, any time you apply a pressure to a fluid you can generate an aerosol. And so that's just a general principle of physics. But when this particular patient was undergoing preparation for intubation, which was apparently a difficult intubation, the patient was on a type of ventilation that they hoped would be able to sustain without actually requiring a breathing tube. And that was very difficult for the patient to tolerate. So during that period of time he was coughing a great deal but also removing his mask. And that was the ideal situation for the cough to generate the droplets and then for the mask to be lifted off so that the droplets were dispersed into the room.

So I think that's a situation that had some lessons learned in terms of the proper sedation of patients, or the proper ventilatory support for patients who are coughing and can't comply with the mask requirement because it's just simply too difficult or too uncomfortable for them.

In addition during the actual intubation, which again I said was a difficult intubation, there is a great deal of opportunity for aerosol generation through the coughing mechanisms, and so forth.

And finally the patient was on I believe a high-frequency ventilatory support, which is a special form of ventilation to try to maintain oxygenation as high as possible with a minimum of airway trauma. And for similar reasons of high volume and highly frequent ventilation, there is an increased opportunity for their airway secretions to become aerosolized in the ventilator setup.

So there are a number of factors that converged here that could have increased the chance for either droplet or aerosol virus to be present in the environment of the patient. And we have seen similar situations in anecdotal reports from other countries involving SARS. And certainly in the tradition of infection control, intubation and airway manipulation is known to be an increased risk factor for several different kinds of respiratory illness. It's not surprising.

Next question from the telephone, please.

MODERATOR: Thank you. That will be from Amy Fagan with the Washington Times. Go ahead, please.

QUESTION: Hi, doctor.

As far as Canada cases go, when you say 'aerosol' are you saying that there's evidence that the virus was hanging in the air for a long time, and isn't this sort of new information? Can you speak to that?

DR. GERBERDING: This has been a concern from the very beginning of the epidemic. Most of the transmission can be accounted for by droplets, which are relatively large particles that spread during cough or sneezing from one person's source to another person's mucous membrane, or sometimes from one person's respiratory source to an environmental object, which then is touched and the virus is indirectly transferred to somebody's mouth or nose or eye.

So that does seem to account for most cases of transmission of SARS. But there have been examples including the hotel in Hong Kong that established the first large international cluster among travelers where the possibility of spread through the air was considered, because the couldn't account for face-to-face transmission as the route in all of the cases involved in the situation.

So airborne has been a concern, and that's why we have implemented airborne precautions really within the very first guidance that CDC put out, we recommended airborne precautions. And those airborne precautions are specifically designed to prevent aerosol transmission of virus.

So the fact that you might see an aerosol in a health care environment is one of the reasons why we're kind of erring on the side of precaution, and also having concerns about unexplained cases that we decided to implement. Not just droplet precautions but also the airborne and contact measures.

Is there another question in the room? If not, then I'll just take one more phone question.
MODERATOR: That will come from Jennifer Warner with Web MD. Please go ahead.

QUESTION: Thank you, Dr. Gerberding.

Can you comment on the CDC's satisfaction with actions being taken in China to control the virus and especially the announcement this morning that they were taking the drastic measure of saying that they would even kill someone that was deliberately spreading the virus.

DR. GERBERDING: I think the CDC has incomplete information about the actions that are being taken in China. We are encouraged to see that there is reporting from a number of provinces, and that gives us a good indication that there is public health activity ongoing in the country.

Of course we are dismayed to learn about extreme measures for control, including the drastic measures that were cited in that report. But we can't confirm that the Chinese government is actually making any such decisions.

So, I think that have a team in China. We're working closely with the WHO collaborators there. And we're doing everything we can to contribute to containment. And our empathy is towards the people there who ar and the tremendous difficulty and burden that this is placing on all of the Chinese people as well as their economy.

Thank you.

MODERATOR: Ladies and gentlemen, that does conclude our conference for today. You may now disconnect.

Listen to the telebriefing

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