CDC Telebriefing – CDC concludes Indiana MERS patient did not spread virus to Illinois business associate
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Press Briefing Transcript
Wednesday, May 28, 2014 1:00 p.m. ET
OPERATOR: Good afternoon and thank you all for holding. The lines have been placed on a listen and only mode until the questions and answer portion of today’s conference. I would like to remind all parties that the call is being recorded. If you have any objections, please disconnect at this time. I would like to turn the call over to Barbara Reynolds. Thank you. You may begin.
BARBARA REYNOLDS: Thank you, Ilan. And welcome to CDC's update on the U.S. response to the Middle East Respiratory Syndrome Coronavirus or MERS. I'm Barbara Reynolds, the Director of CDC’s Division of Public Affairs, and the moderator of today's call. I would like to introduce two participants today. First, Dr. David Swerdlow, the incident manager for MERS Co-V response activities, and the Associate Director for Science at CDC's National Center for Immunization and Respiratory Diseases. Also, we have Dr. Mark Pallansch, Director of the Division of Viral Diseases also in CDC's National Center of Immunization and Respiratory Diseases. Dr. Swerdlow will give brief remarks, and then we'll move to questions for the media from both Dr. Swerdlow and Dr. Pallansch. Also, a transcript of today's update will be posted on the CDC media site as quickly as possible. Now, Dr. Swerdlow.
DAVID SWERDLOW: Thank you, Barbara, and thank you everyone for joining us. This afternoon I’ll be providing updates related to our ongoing investigations into the two confirmed imported cases of Middle East Respiratory Syndrome, or MERS, in the United States. As you recall, on May 17th, we told you that preliminary laboratory testing indicated that an Illinois resident had what appeared to be a MERS Coronavirus infection that may have occurred from a business meeting he had with a man later hospitalized in Indiana and confirmed to have MERS. After completing additional and more definitive laboratory tests, our experts have now concluded that the Indiana MERS patient did not spread the virus to the Illinois resident. To recap, CDC and state and local and public health officials are conducting voluntary testing of people who had contact with two MERS patients that had traveled from Saudi Arabia to the United States. One person in Indiana, the other in Florida. Two kinds of laboratory tests are being done. One type of test conducted by state and CDC labs are done with respiratory samples and quickly– can quickly indicate if a person has active infection with the MERS virus. These tests are called PCR, or polymerase chain reaction assays. Another type of testing conducted on blood samples at CDC is called serology and is designed to look for antibodies to MERS Co-V. Antibodies would indicate that the person had been previously been infected with the virus and developed an immune response. To conduct serology from MERS Co-V, we conducted three separate tests, ELISA, or enzyme-linked immunosorbent assay, IFA, or immunofluorescence assay, and a third more definitive test called the neutralizing antibody assay, which takes longer than the other two tests. Results from these tests are not black and white but require interpretation. The Illinois resident, a business associate who had extended face-to-face contact with the Indiana MERS patient tested negative for active MERS Co-V infection through PCR in the days after his interaction with the MERS patient. Given the Illinois man's contact with the MERS patient, we decided to do serology testing to see if the Illinois man had antibodies to MERS Co-V. Two of these initial preliminary serology tests, ELISA and IFA, were available late May 16 and indicated the possibility that the Illinois resident had been previously infected with MERS Co-V. This compelled us to notify and test those people with whom he had close contact with in the days following his interaction with the Indiana MERS patient in order to be sure no one else had become ill and to prevent further spread of the virus. However, after CDC scientists tested additional blood samples and the completed the slower definitive serology test, the neutralizing antibody test, we have concluded that the Illinois resident had not been infected with MERS Co-V. Public health officials have informed the Illinois resident of the additional serology test results and of our final conclusions. We are extremely grateful to this individual for his willingness to cooperate with public health officials during the investigation. While we never want to cause undue concern among those who have had contact with a MERS patient, it's our job to move quickly when there's a potential public health threat. We are also very committed to being transparent about MERS with our domestic and international partners, the media, and the public. Understanding that the situation is very fluid and our information may change. Because there is still much we don't know about this virus, we will continue to err on the side of caution when responding to and investigating cases of MERS in this country. We are thankful for our state and local public health colleagues in Indiana, Illinois, and Florida who continue to do incredible work to support the MERS response and ongoing investigations. Public health and hospital officials have monitored the health of the family members and healthcare staff who had close contact with the two U.S. MERS patients and collected and tested specimens from them. We have also contacted almost all of the people who are on the flights with the two travelers and we continue to do follow-up interviews and voluntary testing with them. To date, MERS Co-V infection has not been found in any of the contacts of the two people in the in the United States confirmed to have the disease. However, investigations are ongoing and this situation could change. As we speak, our CDC labs are testing specimens. We also remain aware that MERS can and likely will enter our country again. We continue to do surveillance by working with clinicians and public health officials who we rely on for identifying and reporting suspected MERS cases, as well as our partners at U.S. points of entry, including customs and border protection, airlines and emergency medical service units at airports. We also continue our outreach and education efforts for travelers to countries in or near the Arabian Peninsula. This vigilant approach is intended to help CDC reduce any immediate public health threat from MERS as well as help the global scientific community gain a better understanding of how MERS Co-V spreads so we can more effectively control this disease in the future. As CDC continues to gather additional information, officials will update the MERS recommendations as needed. At this time, CDC's recommendations to the public, travelers, doctors, and other healthcare providers has not changed.
BARBARA REYNOLDS: Thank you, Dr. Swerdlow. Ilan, we are ready for questions from the media.
OPERATOR: If you would like to ask a question, please press star 1 on your touch tone phone. You will be prompted to record your name. One moment, please. Our first question today is from Richard Besser from ABC News.
RICHARD BESSER: Thanks very much. I have a question about the ELISA and IFA, whether you have information on what the positive predictive value of those tests is, whether they have been used at all in the Middle East. And in particular, what the positive predictive value is in someone like the man in Illinois who had no symptoms.
MARK PALLANSCH: This is Mark Pallansch. The positive predictive value, of course, will depend upon how common the infection is in a population. So it is, given the specificity that we know for the assay being very high and the prevalence of the infections being low, the positive predictive value is not going to be that good. So this is the reason we have the confirmatory test, because any single test will, again, need to be confirmed to have assurance of a positive result. The specificity, however, does give us a high degree of confidence on a negative result. We are gathering the information relative to the testing that is going on now from cases in the Middle East and will be analyzing that as we go forward.
RICHARD BESSER: Will the experience with this case, might it change how you would respond to a similar situation in someone without symptoms in terms of maybe waiting for the neutralizing antibody test to come back?
DAVID SWERDLOW: We don't think that this changes things a great deal. You know, we really can't wait until we have all of the tests back in order to be able to take public health action. We really do have the public health to make sure the person who we are investigating, his family, his co-workers are all protected. And so in the future, if we get this kind of result, we will still need to take action because we really can't make any mistakes and we want to make sure that we don't allow spread of the virus. That said, we will continue to evaluate these tests and be able to learn more about them as we move forward.
OPERATOR: Our next question is from John Roberts from fox news channel.
JOHN ROBERTS: Hi, good afternoon. Just following along on what Dr. Besser said a moment ago. In terms of when you issue a public alert, if you know that you have potential patient and you can find out from that person the number of contacts and who those people are, what is the value of issuing a public alert with the preliminary test versus waiting until the neutralizing antibody test?
DAVID SWERDLOW: Well, we have made a commitment to keep the public informed about all of our activities and investigations. It's important to make sure that people are aware of what kind of investigations we are doing. And certainly this kind of activity will get into, you know, the public's view and it's important for us to make sure that people understand what we are doing, what the investigation is suggesting and making sure that we are transparent with the public.
JOHN ROBERTS: But if you're issuing alerts that you then have to ten days walk back, what's the value of the initial alert?
DAVID SWERDLOW: Again, it's our priority to make sure that the public is protected and in this case, we just wanted to make sure absolutely certain that the Illinois resident, his family, co-workers of his family, understood that there was this possibility that he had been infected to make sure we test them, to make sure we monitor them, to make sure that they take the proper precautions to prevent any spread. So we have to be absolutely certain that we are protecting the public.
BARBARA REYNOLDS: Next question, please?
OPERATOR: Thank you. Our next question is from JoNelAleccia from NBC News.
JONEL ALECCIA: Hi. Thanks very much for taking my question today. I guess I’d follow up on that a little bit. I'm wondering how you would characterize your response. Do you think CDC jumped the gun on this? I mean, should you have waited at least a bit longer to announce the results? I mean, you rushed it out on a weekend, really.
DAVID SWERDLOW: We were very concerned about this situation and we had– you know, they were preliminary results but they were positive and it was our feeling that it was more important to make sure that we were able to do contact this gentleman, contact his family, contact co-workers of their family and make sure that we were protecting the public health.
BARBARA REYNOLDS: Thank you. Next question, please?
OPERATOR: Thank you. Our next question is from Mike Stobbe from Associated Press.
MIKE STOBBE: Hi. Thank you for taking my question. I was wondering, what could have caused these preliminary results to have been positive? What are some explanations for the positive result you saw earlier this month? I also want to ask about neutralizing antibody assay. How long does that take? You said it takes longer and but I wasn't sure how many days that was. I'd also like to know what the Illinois man said when you informed him.
MARK PALLANSCH: So the neutralization test takes at least five days to get the results. There are several potential explanations for our preliminary results. That is still something that is not completely understood but is also the reason we did additional testing, that we informed everyone that we were going to do. So we not only did additional tests on the specimen but collected additional specimens and tested those as well to make sure that we were getting consistent results before we released them today.
MIKE STOBBE: And what did the man say when you told him about the negative results?
DAVID SWERDLOW: We are really not at leave to be able to discuss that. Although, he has very good relations with the local health department and we've been in contact with him.
MIKE STOBBE: Thank you.
OPERATOR: Our next question is from Elizabeth Cohen from CNN.
ELIZABETH COHEN: Hi. Thanks so much. The three tests for serology, the ELISA, and IFA, and the neutralizing antibody assay, can you tell us the dates that you started each of those?
MARK PALLANSCH: All of these results have been– all of the test results have been occurring over the last 12 days. I don't have the exact dates for each of the tests.
ELIZABETH COHEN: But how does it work, do you start each of them on the same day? Do you say, all right, we're going to start all three of them right now? Or do you do one, wait for the results, do the second, wait for the results and then do the third? Are they at the same time or one at a time?
MARK PALLANSCH: They are done on a specific testing schedule and we start with the ELISA but then dependent on those results we then do the confirmatory tests or resolve any indeterminate test in sequence. So they are not done in parallel.
ELIZABETH COHEN: Okay. Why not –since the neutralizing antibody test is the most definitive and gives you the best result but it takes the longest, why not start that one right away? You wouldn’t have had the situation you have here if you’d done that, right?
MARK PALLANSCH: Sometimes that could be true. The biggest issue is it is time and labor intensive to perform. Therefore, cannot be routinely applied to all specimens. So we do have a specific screening algorithm that has high sensitivity, yet to be able to rapidly identify potential positives and then clarify those with the more definitive confirmatory testing.
ELIZABETH COHEN: But given the situation that you're in, you have a press conference and then gosh, this guy has it and then ten days later you have to take it back, do you think you should rethink that algorithm?
MARK PALLANSCH: We are, of course, assessing algorithms for any of our testing on a routine basis based upon what use for these tests as well as whether we're doing investigations or diagnostic testing. At this point, this is the most efficient approach to our trying to identify potentially infected individuals. It, of course, is a new set of tests and, of course, that's what we are, you know, evaluating the test. It should be mentioned that, of course, the neutralization test uses live MERS virus and, therefore, must be conducted in a high-containment laboratory. So it is not simple to immediately test all hundreds of samples in that environment.
BARBARA REYNOLDS: Thank you. Next question, please?
OPERATOR: Our next question is from Betsy McKay from Wall Street Journal.
BETSY MCKAY: Hi. Thanks very much. I was just wondering if the fact that this Illinois businessman is not, after all, infected and you know clearly didn't become infected in this close face-to-face meeting, does that tell you any more about the disease– the dynamics of MERS, either give you assurance that it might not spread as easily as this case might have suggested or is that something that you're still concerned about and looking out for?
DAVID SWERDLOW: Well, I think you answered the question. I think that it was– when we first heard about this case, it was a little bit surprising and it certainly demanded our attention. It doesn't mean that this kind of level of contact is not possible to transmit. But it hasn't been the case in the Middle East that not extended contact leading– would have led to transmission. So actually it is a little reassuring that this gentleman was not a case. The epidemiology is more consistent with the Middle East where it takes more extensive contact or contact in health care settings. So that doesn't mean that in the future we couldn't have somebody transmit the virus with less– less levels of contact. But it is actually a little reassuring that this kind of contact did not lead to transmission.
BARBARA REYNOLDS: Thank you. Next question, please.
OPERATOR: Thank you. My next question is from Richard Harris from NPR.
RICHARD HARRIS: Hi. Let me say, first of all, I appreciate that you guys are giving us the information you have when you have it and I just want to get that on the record. Some of my colleagues seem to be wondering why you shared early but I appreciate you sharing early. My question is, did the man in Illinois take any precautions? Was he ever quarantined? What sorts of activities was he subjected to, if you will, during this period of uncertainty for him?
DAVID SWERDLOW: Yeah. That's actually a great question. And, yes, until we had several tests back that confirmed that he didn't have active infection, he was asked to wear a mask and not go around other people and not come in contact with crowds, et cetera. So, yes, we did take public health action based on these results until we learned more. So I think it is really important to know that, you know, we were concerned about this Illinois resident. We were concerned about his family and co-workers of the family and we did think that if this person had been infected, there could have been real risk to other people around him. And real risk is a virus that has a 30 percent mortality rate at this time. So you really can't take any chances and that's why we chose to take the action that we did.
BARBARA REYNOLDS: Thank you. Next question, please?
OPERATOR: Thank you. Our next question is from Bob Roos with CIDRAP News.
BOB ROOS: Hi. Thanks for taking my question. I was wondering, you mentioned that the Illinois man tested negative initially on the PCR test and I was wondering how much confidence you have in the PCR tests, how reliable those are. And also I was wondering how many contacts with the Illinois man actually were tested and was that testing still ongoing until now?
DAVID SWERDLOW: All the testing for the contact with the Illinois resident were negative for MERS, which was very reassuring. And–
MARK PALLANSCH: So the PCR, again, the resident had tested negative twice and so– and the serology for the contact of the contacts is complete as well as other specimen testing.
BOB ROOS: But how reliable are the– is the PCR test, though? He tested negative on that but you followed up with the serology test. Was the serology testing really necessary, I wonder.
DAVID SWERDLOW: This is a new virus and these are new tests and we certainly think the PCR is good but we don't have the kind of ongoing information that you would have for a test that has been used for years and years on a specific illness. So we think the PCR is good but certainly if we had one person with a negative PCR, we would still be interested in monitoring that person and testing again and doing serology. As you recall, for the close contacts of both the Indiana and the Florida case patient, we didn't do one PCR test. We did two PCR tests to be absolutely certain that they had not been infected. The answer is, we don't know exactly how good the PCR test is. We think it's good but we don't like to take any chances in these types of circumstances. And that's why we tested, close contacts with two PCR test, one when they were first contacted and one at the end of their incubation period and do the serology. We just don't want to take any chances.
BOB ROOS: Thank you.
BARBARA REYNOLDS: Next question, please.
OPERATOR: Thank you, our next question is from Michael Smith from Medpage Today.
MICHAEL SMITH: Yeah. Good afternoon. Just one follow-up and then another question. Dr. Pallansch, you said just a few minutes ago, you said there were several possible explanations why the ELISA andIFA would turn up positive but the neutralizing antibody would be negative. Could you elaborate on that a little bit? And the second question is the trend of cases internationally and specifically in the kingdom of Saudi Arabia has been down since the 21st of April. Is that reassuring? Does that sort of tend to make us think there is less risk of more importations? So that’s two questions.
MARK PALLANSCH: So I’ll take the first one. The most common explanation is that there is some cross-reactivity with a coronavirus and because of the nature of the antigen in the test; this is a possibility that cannot be excluded and in the case of other types of respiratory viruses is known to occur. So that's the most likely explanation in terms of how you get a false-positive signal in an ELISA.
DAVID SWERDLOW: And in answer to your second question, we are certainly pleased to see the numbers of reported cases going down. But I don't think that means that we're being any less vigilant. We're still taking very aggressive approach to making sure that doctors know how to recognize infection with this virus. They know how to test, they know where to send the tests to and we are being aggressive in knowing that people know how to deal with an onward spread if a case is identified. Yes, it's reassuring if cases start to go down but we certainly would not become any less vigilant because, as mentioned, it's a new virus and it has a high fatality rate and we're still very concerned.
BARBARA REYNOLDS: Thank you. We have time for just one more question, please.
OPERATOR: Thank you. Our final question today is from Robert Lowes from Medscape Medical News.
ROBERT LOWES: Hi. Given the fact that the serology tests that you have used seem to be fuzzy, at least the first two, is there any thought to developing an alternative way to test blood samples? In other words, can you adopt a better method? Is there any thought to developing a better method?
MARK PALLANSCH: Well, the scientists around the world have been working on development of serology assays and several other groups have other assays. We are also going to be developing additional assays to try to improve both the sensitivity and specificity. So, again, this is an ongoing process. Other investigators around the world are working on similar types of problems and, again, we will evaluate these assays as they become available and then have opportunities to share the technologies among the different partners that we work with.
BARBARA REYNOLDS: Thank you; this concludes today's update on MERS. I'd like to thank you Dr. Pallansch and Swerdlow. I'd like to spell their last names in case you need it. Dr. Swerdlow is S-W-E-R-D-L-O-W. And Dr. Pallansch is P-A-L-L-A-N-S-C-H. They are both MDs. We will have a transcript posted on the CDC's media website and if media has follow-up questions, please call CDC's media office at 404-639-3286. Thanks. Dr. Swerdlow is a– I’m sorry. Dr. Pallansch is a Ph.D. and we have that incorrect on the media advisory, also. So Dr. Pallansch is a Ph.D. Thank you.
OPERATOR: Thank you. This does conclude today's conference. You must disconnect at this time.
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