Homeland Security

CDC Puzzles over SARS Transmission

(Travel alert in place; modes of transmission under scrutiny) (7050)
Severe acute respiratory syndrome (SARS) has been detected in 13
nations, but health officials in those countries are seeing the
disease unfold in different ways, according to officials at the U.S.
Centers for Disease Control and Prevention (CDC). CDC Director Julie
Gerberding and other experts discussed the spread of the disease and
their efforts to combat it in a briefing March 29 at the agency's
Atlanta, Georgia headquarters.
CDC reports 62 suspected cases in the United States compared to the
more than 500 reported in Hong Kong alone. Gerberding said the U.S.
cases so far remain confined to people who have traveled in the
affected countries, or individuals who have come in direct,
face-to-face contact with SARS-infected patients. In Hong Kong, in
contrast, officials have found indications of disease spreading among
individuals in an apartment building, suggesting the possibility of
airborne transmission of infected droplets.
"We are not experiencing any sign of community transmission at this
point in time, but we are alert to it," Gerberding said. "We are
monitoring potential contacts very carefully."
As of March 31, the World Health Organization reports more than 1,600
cases of SARS with 58 deaths. More than 1,200 cases are located in
mainland China and the Hong Kong Special Administrative Region of
China.
SARS appears to be caused by a virus in the coronavirus family, the
cause of the common cold. CDC researchers first offered that
hypothesis, which has since been substantiated by researchers working
in other laboratories. CDC officials say it can be killed with
commonly available disinfectants.
The CDC head indicated that some patients may be more contagious than
others, and more likely to spread the disease to others. "For example,
in Hanoi ... there was one patient who was a source for health care
worker transmission and approximately 56 percent of the health care
(workers) who had direct contact with the patient appeared to have
acquired SARS," Gerberding said.
The CDC has issued a travel advisory, suggesting that individuals with
optional travel to the worst- affected countries may want to postpone
their plans.
Gerberding expressed condolences at the SARS death of World Health
Organization physician Carol Urbani. He died of SARS in Thailand,
after having been the first WHO official to identify the outbreak
several weeks ago.
Following is an excerpted version of the CDC briefing transcript:
(begin excerpt)
CDC Telebriefing Transcript
March 29, 2003
MODERATOR: Thank you for standing by. Welcome to the SARS update
conference call.
DR. GERBERDING: Thanks for joining us for another update on the Severe
Acute Respiratory Syndrome or SARS. What I'm going to do today is just
give you a brief recap of where we are in the epidemic and then I will
talk about some new guidance that CDC will be issuing today to help
prevent the spread of this infection here in the United States.
I'd like to first begin, though, with just a reflection on some sad
news that CDC received this morning. Dr. Urbani, who is the WHO
physician investigating the outbreak in Hanoi, died of SARS that he
acquired during his investigation. He was a very close colleague of
ours and someone that we had worked closely with in both Hanoi and
Thailand through the past several years, and we are very sad and our
condolences certainly go to his family and his colleagues as well as
our colleagues in the area who've been working with him over the past
few weeks on this investigation.
The global epidemic continues to expand. Today, WHO is reporting 1,491
cases and 54 deaths, plus the 62 cases that we are reporting here in
the United States.
As you know, the U.S. cases are constantly undergoing revision and
updating as additional information about the patients is determined,
so that number may change over time.
We continue to regard the new coronavirus as the leading hypothesis
for the etiology of this condition. The evidence is mounting from a
number of international laboratories, that this is indeed the case;
but we are also exploring other potential viruses as are our
collaborators, and we will keep you posted as we go forward on that
part of the scientific investigation. A number of things are in
progress, including sequencing of the whole virus genome, and we'll
have more information on that, potentially next week or the week
thereafter.
We are at a situation in time where we recognize that the disease is
still primarily limited to travelers, to health care personnel who
have taken care of SARS patients, and to close contact with SARS
patients.
The affected travelers are those who have been in Hong Kong, in Hanoi,
in Singapore, and in mainland China, for the most part.
We believe, based on what the investigations have shown us so far,
that the major mode of transmission still is through droplet spread
when an infected person coughs or sneezes and droplets are spread to a
nearby contact. But we are concerned about the possibility of airborne
transmission across broader areas and also the possibility that
objects that become contaminated in the environment could serve as
modes of spread.
Coronaviruses can survive in the environment for up to two or three
hours,and so it's possible that a contaminated object could serve as a
vehicle for transfer to someone else.
In health care settings, we have already initiated guidance to protect
against droplets, airborne and contact spread of this virus, and today
we're issuing an update on how to protect people in homes of SARS
patients.
We know that the individual with SARS can be very infectious during
the symptomatic phase of the illness. We don't know how long the
period of contagion lasts once they recover from the illness and we
don't know whether or not they can spread the virus before they have
the full-blown form syndrome.
But most of the information that the epidemiologists have been able to
put together suggests that the period of contagion may begin with the
onset of the very earliest symptoms of a viral infection, so our
guidance is based on this assumption.
If we learn more or we learn something different as we go forward and
intensify our investigations, we will of course update or change our
guidance.
SARS patients are either being cared for in the home, or who have been
released from the hospital or health care settings, and are residing
in the home, should limit their activities to the home. They should
not go to work. They should not go to school. They should not frequent
public places until at least ten days after they are fully
asymptomatic.
In addition, if they're coughing or sneezing, they should use common
sense precautions such as covering their mouth with a tissue, and, if
possible, and medically appropriate, they should wear a surgical mask
to reduce the possibility of droplet transmission from them to others
in the household.
In addition, and very importantly, they should use good hand hygiene,
and that means washing your hands with soap and water, or using an
alcohol-based hand rub frequently, and particularly after any contact
with body fluids.
For the people who are living in the household with the SARS patients,
and who are otherwise well, there is no reason to limit activities at
this point in time. The experience in the United States has not
demonstrated spread of SARS from household contacts into the community
and so we are not advising any restrictions on the activity of
contacts at this point in time.
However, it's very important that contacts with SARS patients be alert
to the earliest symptom of a respiratory illness. That may be fatigue,
headache or fever, and the beginnings of the usual upper respiratory
tract infection, and if they have any symptoms suggestive of an
impending illness, they should contact a medical provider, alert them
that they are a SARS contact, so that the health care system can
advise them where to come and get evaluation, and prepare the delivery
system to implement the appropriate infection control precautions so
that others are not exposed in the health care setting.
Contacts with SARS patients should also of course use hand hygiene and
use the appropriate surgical mask to prevent contact with droplets, if
the SARS patient in the home is unable to wear a mask.
We also are updating our guidance to travelers. I think that the
travelers at risk for SARS are those who have been in mainland China,
in Hong Kong, in Hanoi and in Singapore.
However, we recognize that there are passengers who moved through
these areas for brief periods of times and are arriving here in this
country indirectly, after being in those countries, so right now we
are meeting both direct incoming flights from the affected areas as
well as passengers who are arriving from different regions and have
passed through those areas en route.
The alerting is being expanded to include arriving passengers from
China, from mainland China, and from Singapore at this point in time.
In addition, the alert extends the period of passenger monitoring to
ten days. Previously it had been seven days but we are aware of some
patients that may have a longer incubation period, and to be on the
safe side, we want to make sure that they seek medical attention if
they develop any symptoms within ten days of departure from one of the
SARS regions of the world.
These travel alerts do not include passengers coming in from Canada.
The epidemiology of the SARS in Canada is very different and there is
not a risk from incoming travelers at this point in time.
WHO is not issuing any travel restrictions. We are not issuing any
travel restrictions either, but WHO has also implemented procedures
for screening passengers before they leave the country of SARS origin.
They're asking countries to evaluate departing passengers for
respiratory illnesses or other signs that could represent SARS. In
part, this is because there are some early reports that passengers
traveling with a SARS patient on board could be at risk for acquiring
this infection, and we don't want to have any cases acquired during
flight or during transfer on a ship or other vehicle.
So the travel alerting process that's already been in place, and
actually we've issued more than 150,000 alerts, is being expanded and
will be involving 23 ports of entry into the United States.
So let me just stop here and take questions and I'll take a caller on
the phone first. Can we have the first call.
I don't have a caller on the phone. I'll take someone from the
audience.
MODERATOR: Ladies and gentlemen, if you wish to ask a question, please
press one at this time.
Okay. Our first question comes from the line of Miriam Falco with CNN.
Please go ahead.
QUESTION: Hi. Can you hear me?
DR. GERBERDING: Yes. We can hear you now.
QUESTION: Excellent. I don't know what that was. First of all, thanks,
again, for having this.
The Canadian health authorities have issued quite a restrictive
quarantine, now expanding to a second hospital.
Why are you not issuing any quarantine? Is it because you can't or
because the situation is not so dire?
DR. GERBERDING: Well, first of all, we have been in constant
communication with Canadian health authorities and they are not
actually issuing a quarantine. They are issuing a voluntary
self-isolation policy which is slightly different than a regulated
quarantine.
The main reason we are not taking this step right now, in this
country, is because the epidemiology of our problem is very different
than the outbreak that Canada is experiencing in Toronto.
Although I reported 62 cases under investigation here, two of those
cases are in health care workers and there have been no further signs
of spread in that particular cluster. Five cases have been in
household contact and the rest of the cases have all been in travelers
coming in from SARS areas.
So we are not experiencing any sign of community transmission at this
point in time, but we are alert to it, we are monitoring potential
contacts very carefully, and if we see evidence that our infection
control measures are not containing spread within communities, then we
will have to reconsider whether additional steps are necessary.
I'll take another question from the floor here.
QUESTION: I notice that you list mainland China but now Taiwan. How
significant is the risk in Taiwan?
DR. GERBERDING: Taiwan is a country that is reporting cases and they
are included in the travel advisory for incoming passengers.
A question from the telephone.
MODERATOR: Our next question comes from the line of Larry Altman with
New York Times. Please go ahead.
QUESTION: Yes. Dr. Gerberding, given the fact that Hong Kong health
officials now are reporting suspect cases from an apartment complex,
large numbers, apparently spread by one or two infected individuals in
that area, how do the United States guidelines take the possibility of
airborne transmission into effect?
You touched on this just a moment ago but given the new news, could
you elaborate on that.
DR. GERBERDING: Yes. The information that we're getting from Hong Kong
does suggest that in at least one apartment complex there has been
spread. We can't identify yet, to what extent the individuals in that
apartment have had face to face contact with each other, to what
extent they might have contacted contaminated environments in that
facility or to what extent airborne transmission could play a role.
It's obviously something that we're concerned about and we're working
hard to get that sort of information.
There are other clues that face-to-face contact is not always the only
means of transmission. Right now, in this country, our infection
control precautions in health care settings in homes appear to have
limited spread of the disease, but as I said, we are monitoring very
carefully and if we see evidence of airborne transmission or failure
of our current guidelines to contain this, we will be willing and need
to take additional steps.
A question from the audience.
QUESTION: Following up on the question about modes of transmission,
you mentioned, when you began to speak, that there's some indication
that coronaviruses may survive on surfaces for a while, so could you
discuss any implications that might have, particularly for airplanes
or vessels, anything like that, in terms of this infection.
DR. GERBERDING: Yeah. I'll ask Dr. Citron [ph], who's our expert in
international travel, itches [?], and infection control, to see what
he can tell us about this infection in planes and boats.
DR. CITRON: Thank you, Dr. Gerberding.
We have issued preliminary guidance on appropriate means for
disinfection of commercial aircraft as well as very specific and more
focused guidance for disinfection of an aircraft that might be used in
a medical evacuation of a high-risk or critically-ill patient, and
those are available on the Web.
Although there's a possibility [inaudible] spread, this is a virus
that's routinely susceptible to commercially available, normal types
of disinfectants that are used in hospitals, and that's basically what
you'll see in that guidance. So there's not need for taking
extraordinary measures or using extremely caustic or dangerous types
of materials, but the routine types of disinfectants are available and
the specifics are on the Web site announcement [?].
QUESTION: Just a follow up. To follow up. What about disinfection in
the home? Do you have guidelines for that? Is it just a question of
chlorine or--
DR. CITRON: I think it's the same kind of principles that are going to
apply, you know, standard household disinfectant agents to clean
surfaces and bathroom areas, and things that may have come in a lot of
contact with a potentially-infected patient, ought to be adequate.
DR. GERBERDING: You know, any time we have a new disease there are
always a lot of questions about disinfection in the home, and I think
one of the themes that's been most helpful in the past as we've dealt
with AIDS or other infectious diseases--to use common sense. Prudent
housekeeping policies are appropriate for home hygiene under any
circumstance and those certainly are appropriate when there's a new
infectious disease as well. So the common sense measures that we take
for sustaining cleanliness in the home and food safety, and so forth,
are appropriate under these circumstances as well.
May I have a phone question, please.
MODERATOR: We have a question from the line of Anita Manning with USA
Today. Please go ahead.
QUESTION: Hi. Thanks very much, Dr. Gerberding. Actually, one of my
questions has already been answered, but I did wonder if you could
talk a little bit more about what travelers are experiencing in terms
of what the CDC is informing them of. What are you doing?
DR. GERBERDING: What we are doing when passengers arrive at the 23
ports of entry involved in this alerting process in the United States
is delivering to the passengers at the time that they're disembarking
a health alert card, a small card that we now have translated into six
languages, that advises them to be alert of any evidence of fever or
respiratory symptoms for the ten days after they've left one of the
SARS countries. The card specifically mentions the countries of
concern.
In addition, there's a second section of the card that is information
to clinicians, so if SARS patient does seek clinical attention, the
clinician understands, they bring the card in and it gives them the
specific advice, provides them information on how to get more
up-to-date information on SARS, and also how to contact CDC and the
importance of reporting any known or suspect cases.
So it's a mechanism to remind people at the point of departure, that
they've been in an area where they could possibly have come in contact
with someone with SARS and that they need to be alert to the earliest
possible symptoms, so that they can get care and protect others.
Can I have another phone question.
MODERATOR: We have a question from the line of Betsy McKay with Wall
Street Journal. Please go ahead.
QUESTION: Hi, Dr. Gerberding. Thank you very much for holding this
briefing.
I was just wondering if you could update us on treatments that are
being used in the U.S. for SARS patients. I understand that you have
not issued specific treatment guidance but I'm just wondering if there
are any changes in treatment that are being used around the country
over the last few days and if there are any particular anti-viral
medicines, or therapies that are being used that may seem promising?
Thank you.
DR. GERBERDING: CDC is working with FDA and NIHD and USAMRIID and
others to try to identify drugs that might have activity against this
coronavirus, but as of today we have no leading candidates on the
shelf, that we could recommend for clinical treatment.
The patients in the United States are being treated according to the
guidance that we've issued to clinicians as well as standard
management for pneumonia, and that does include treatment empirically
for other causes of pneumonia, because at the initial presentation
this disease could easily be confused with other common things for
which we do have specific therapy.
So clinicians are advised to have a broad differential, to initiate
antibiotics, if that seems appropriate under the clinical
circumstances, and as they learn more, and more diagnostic testing is
done, to stop those unnecessary treatments if, indeed, the condition
does seem to be most consistent with SARS.
We have no evidence, unfortunately, right now, that any specific
anti-viral therapy, or steroid treatment, or other agents that are
targeting this virus, are of any benefit to patients. We hope we'll
learn more as we go but that is the status of clinical care today.
How about a question here.
QUESTION: Hi. Jim Carr with Reuters. Just a follow-up on the earlier
comment you made about Taiwan, because as I understand it, the cards
that you were talking about do not include Taiwan among the listed
nations.
Does that mean that Taiwan is less dangerous?
DR. GERBERDING: Let me ask Dr. Citron to take this question. There's a
couple points of confusion here.
DR. CITRON: Thank you. I think there is the potential for confusing
the two strategies. The passenger alert cards, the yellow cards that
disembarking passengers get, is our surveillance tool, to be alert to
the earliest possible cases, and consequently it's broader. It lists
those three countries, China, Vietnam and Singapore at this point, and
we want to be able to detect the first case from any of those areas.
The guidance that goes up to outbound travelers, the travel advisory
which recommends deferring nonessential or elective travel, that is
focused on helping somebody judge whether they should go to an area of
risk and it's based on a risk assessment from the data that we have
available or a risk assessment because of the absence of information.
So our current understanding of the risk, of the cases in Taiwan, as
well as Canada and Toronto, is significantly different and
significantly more confined, and consequently there isn't evidence, at
this point, to suggest people defer that travel to Taiwan as opposed
to Guangdong Province, for example, where there's a community epidemic
going on.
So the outbound is guidance to help you assess risk about where you're
going. The inbound is a surveillance tool, so we can find all cases
early, and act on them quickly, get them to health care and be
isolated. I hope that clears that up.
DR. GERBERDING: So it's on the list.
Can I have a telephone question.
MODERATOR: We have a question from the line of Robert Bazell with NBC
News. Please go ahead.
QUESTION: Hello, Dr. Gerberding.
Given what's happened in Hong Kong, and southern China, and given
what's happened in Toronto, how concerned are you about the
possibility of a community outbreak in the United States?
DR. GERBERDING: We are very vigilant about the possibility of spread.
We recognize that there are at least some patients with SARS that are
extremely efficient transmitters. We don't know to what extent all
patients are particularly infectious but there are clearly some who
appear to be very highly infectious, and, for example, in Hanoi where
there was one patient who was a source for health care worker
transmission and approximately 56 percent of the health care who had
direct contact with the patient appeared to have acquired SARS.
So given that high degree of contagion and what we know about spread
of cold viruses, I think we are very alert to the possibility that
this could spread outside of the confined populations that I've
mentioned, travelers to the affected areas, close household contacts,
and health care workers. But we are not seeing that now and we are
looking for it very closely.
So if we begin to appreciate that, we will have to expand our
recommendations to be more inclusive of special protective measures
for contacts.
I'll take another phone question.
MODERATOR: We have a question from the line of Hija Charapadeya [ph]
from CBC Radio Canada. Please go ahead.
QUESTION: It's actually Pia. Dr. Gerberding, I'm wondering how would
you characterize the situation in Canada, specifically in Toronto, now
that we upwards of about 70 probably and suspected cases?
And as a follow-up, you said the epidemiology of SARS in Canada is
very different. What do you mean by that?
DR. GERBERDING: In Canada, unfortunately, when the initial patients
arrived with SARS, we did not yet appreciate the illness and we did
not know that infection control measures were appropriate, so the
earliest patients were not placed on the special isolation precautions
that we're talking about now, generically.
I think that allowed the epidemic to get started there and to spread
to more people before there was a chance to really intervene with
appropriate infection control.
We are incredibly impressed with what Canada is doing and what the
local health officials are doing in Toronto. I think they're erring on
the side of caution. They're taking every step that we could imagine
would be appropriate given the circumstances that they're facing.
We also have a liaison from Canada here in our emergency operations
center and are preparing to send one of our CDC staff to Canada to
make sure that our information exchange is complete and that we are in
close collaboration and are aware of the situations in both countries
as they evolve.
So I think we are learning from Canada as we go and we are keeping a
very close watch on the situation there.
Can I have another telephone question.
MODERATOR: Yes. We have a line from the question of Tom Maw [ph] with
Los Angeles Times. Please go ahead.
QUESTION: Can you give us a brief overview of the evidence that now
supports the idea that this is in fact a coronavirus.
DR. GERBERDING: I'll take a stab at that and I'll ask Dr. Hughes to
chime in. Dr. Hughes is the director of the National Center for
Infectious Diseases. The evidence comes from a convergence of many
types of laboratory investigations ongoing in many of the laboratories
that are part of the WHO collaboration, including CDC.
First, we have isolated the coronavirus from two patients, here, in
the United States and this work is going on elsewhere additional
isolations are reported. We are using PCR or polymerase chain reaction
technology to identify very specific pieces of the coronavirus in the
secretions and fluids from many, many of the case patients.
We have developed an antibody assay which detects antibodies to this
new coronavirus with a high degree of specificity and I think very
compelling, some of the patients who have negative antibody tests at
the beginning of their illness, subsequently, in paired [?] serum have
demonstrated new development of antibody within days after their
infection occurred. So they are developing an immunologic reaction to
this new coronavirus and that's really strong evidence of infection.
It doesn't necessarily mean the infection is a cause of the pulmonary
infection or the respiratory symptoms, but, clearly, that's very solid
evidence that disease is occurring, the body is responding to it,
specifically, and I think that is a very important source of
information, and I'll let Dr. Hughes add the breaking information
about what's probably coming out of the lab today.
DR. HUGHES: Well, many laboratories here at CDC, as well as around the
world, have been hard at work at this for some period of time. A week
ago today, there were no antibody tests which could be used to
diagnose this infection. It's a result of considerable hard work. We
now actually have two antibody tests that look quite promising and
seem to be reproducible in different laboratories, and among the
things we're doing is working to get ready to transfer diagnostic
testing capacity to public health laboratories around the country, so
that before too long, I'm hoping that tests will be available much
more locally.
I should also say that we know that laboratories in at least seven
other countries now have evidence for coronavirus, looking like it
plays an important role in causing this syndrome.
So the preponderance of evidence in support of coronavirus as the
cause continues to mount.
QUESTION: You had mentioned the screening process that's going on at
the ports in the various countries.
What about the United States? Is there any screening being done on
ingoing or outgoing passengers?
DR. GERBERDING: Let me first just offer a point of clarification. The
WHO just issued this advice to the involved countries and recommended
some steps they should take for departing passengers and you can find
that on the WHO Web site.
Since I'm not aware, at this point, how much implementation has
occurred already, I think there are going to be some difficulties in
getting this implemented at every airport, and that's why we are
continuing to alert the arriving passengers from these areas, to make
sure that they are included in our catchment.
What really is the situation here is that arriving passengers are
alerted. If we have people who are travelling to those areas, we're
not issuing an airport-specific alert but we are putting the usual
kind of guidance that goes up on our Web site and, you know, it's
actually our travellers Web site is the most frequently sought
component of the CDC Web site, so we know that that is a common place
where people go for information when they're traveling abroad, and
travelers clinics would also have this information and advice as
people go in and prepare for their vaccinations or whatever is out
there, leaving for whatever travel they're taking.
So our approach is primarily alerting people on their way back home,
or on their way to the United States from these areas, and
secondarily, to issue the generic statement that if you're traveling
to this region you may wish to defer elective travel until such time
that we know more and can do a more thorough assessment of what risks
are present.
We are not medically screening incoming passengers but if a passenger
is identified as having illness on a plane or a ship, they are met by
the health authorities in that state, in conjunction with the CDC
officials, and they are evaluated and we have done that several times.
So if there is evidence of a symptomatic person, on arrival they are
assessed, and if necessary, the other passengers are evaluated and
they're monitored prospectively, to make sure that they haven't been
exposed as they go forward through the incubation period.
A telephone question, please.
MODERATOR: We have a question from the line of John Kerry with
Business Week. Please go ahead.
QUESTION: There have been sort of conflicting views of where we are in
the epidemic, whether it's continuing to spread or under control, and
it may vary as to what country you're in. I was just hoping you could
sort of address the big picture here and say what you think about
where we stand, and also what lessons have been learned so far about
the ability of the public health infrastructure to respond to this
sort of thing?, and again, that may vary by country as well, I would
think.
DR. GERBERDING: Well, from the standpoint of CDC, I would say that we
are very concerned about the spread of this virus, particularly in
Asia. We recognize this as a epidemic that's evolving differently, in
different geographies, but nevertheless, it is a respiratory virus, it
does appear to be transmitted very efficiently, and what we know about
respiratory viruses suggests that the potential for infecting large
numbers of people is very great.
So we may be in the very early stages of what could be a much larger
problem as we go forward in time. On the other hand, this is new, we
don't know everything about it, and we have a lot of questions about
the overall spread.
The patterns of transmission in the individual countries vary,
depending on where the primary foci of transmission is occurring.
In Hong Kong, the situation is particularly alarming because we have
several hospitals that are affected, and there are so many health care
workers in each of these hospitals that could have been exposed or who
are developing SARS, that there's already a multiplier in the
community. Every health care worker has household contacts, those
contacts, when they become ill, have had other exposures.
So we are very concerned about the speed and the amplification process
in Hong Kong. On the other hand, the health officials there are taking
extremely efficient and aggressive steps at this point in time to
contain spread in that community, including closing schools and
closing hospitals, and cohorting health care workers and patients.
So it remains to be seen whether or not those measures will attenuate
the spread. The biggest unknown is of course what is going on in China
and we are desperate to learn more about the scope and magnitude of
the problem there, because that really I think will be the biggest
predictor for where this will be headed over the next few weeks. Yes?
QUESTION: Returning to the issue of for how long patients are
contagious, and whether there's an asymptomatic contagious state,
could you discuss whether you've been able to start any studies yet
and what sort of studies there are.
DR. GERBERDING: There are studies going on to try to define the period
of infectivity or the timeframe in which an asymptomatic person could
have the virus, not yet be sick and transmit it to someone else.
One of the important studies going on is to look at passengers who
traveled in airplanes with SARS patients, and so already we have three
separate cohorts of passengers who traveled on the same plane with
someone we knew was incubating SARS or had SARS during their travel
experience.
So far, those studies have not identified evidence of transmission
before people become sick but the numbers are small and we can't draw
any conclusions at this point in time.
Likewise, when we have the test that Dr. Hughes was talking about, the
antibody test, we'll be able to evaluate household contact of patients
and measure their antibody response to see whether or not they were
exposed and actually didn't get the full spectrum of disease but had
evidence of asymptomatic infection, and that will help us calculate
the attack rate or the proportion of exposed people who actually
develop infection.
These are fundamental aspects of understanding any epidemic and we are
just in the early phases of getting those pieces of information pulled
together from across the world.
The WHO has been incredibly helpful in supporting all of these
collaborative efforts.
Let me take a telephone question, please.
MODERATOR: Our next question comes from the line of Elizabeth Cohen
with CNN. Please go ahead.
QUESTION: Hi, Dr. Gerberding. I have two questions. The first one, I
know it's very hard for you to be real specific about this but this is
what has everyone freaked out, so I feel like I need to ask you
because people are asking me.
Could, if you're in an elevator, on the other side of an elevator with
someone who has SARS, could they spread it to you? If you're three
steps behind in an escalator. If you're on the same step of the
escalator. I mean, what kind of distance are we talking about, because
people are really anxious about that.
DR. GERBERDING: You're breaking up a little bit but I think I caught
your question, which is basically what is the risk from brief
encounters, in public settings, of acquiring this from someone who has
the illness, examples of the escalator or the elevator.
The bottom line is that we don't know but what we can tell from
looking at the epidemiology and the patterns of transmission so far,
there is not evidence, at least in this country, to suggest that those
activities are posing any risk.
Concerns that I mentioned earlier focused on droplet transmission, so
if you were in the elevator and an infectious person literally coughed
on you, it's conceivable that you could acquire a respiratory
infection, including SARS, through that mechanism.
On the other hand, most of the information suggests that fairly
prolonged contact, on a face to face basis, is typical of the
transmissions.
There are anecdotal reports, that we haven't confirmed yet, of much
briefer contact. There's been a concern expressed about the potential
for airborne or surface contamination in the apartment in Hong Kong,
and these are all open questions that we are aggressively pursuing
here.
So we will learn as we go and as we said from the very beginning, we
are erring on the side of taking extra precautions because we can't be
confident that we are offering the best protection without taking
those kinds of steps.
In environments where those infection control precautions have been
implemented, there's been a dramatic reduction in spread to health
care personnel, so it is possible to contain the infection through
these measures but we don't know if that will be a 100 percent
effective and we don't know which of the measures is the most
important at this point in time.
Can I have another telephone question, please.
MODERATOR: We have a question from the line of Larry Altman with New
York Times. Please go ahead.
QUESTION: Yes. This is a follow-up question that I should have asked
earlier, Dr. Gerberding. Are the new guidelines going to be on the Web
site right now?
DR. GERBERDING: They are likely to be up as we speak. They were
issued, they're out, they're in the process of being put out through
the health alert network, and as soon as we can get the Web button
pushed, they'll be up.
MODERATOR: We have a question from the line of Kida McPherson with
Star-Ledger. Please go ahead.
QUESTION: Thank you; thanks, Dr. Gerberding.
My first question was: Just could you please repeat the number of
American cases. It broke up and I couldn't hear that number. My second
question is: You mentioned at the very beginning of this briefing that
Dr. Urbani of the World Health Organization had passed away.
I would think that he would have had access to, you know, the best
knowledge about how to protect himself, so I'm
wondering--unfortunately, did you learn anything? Was he exposed in a
way that you hadn't expected? Is there any kind of insight into that?
DR. GERBERDING: Thank you. I would take your first question. There are
62 patients in the United States under evaluation for SARS right now.
Two of those are health care workers and five of them are contacts of
SARS patients, household contacts of SARS patients.
With respect to the mode of transmission to Dr. Urbani, at this point
I can't tell you the best hypothesis for that, but I will say that he
is the person who went into the hospital where the affected patient
was in Hanoi first. He was the first investigator to be there and he
arrived at a time when infection control precautions were not in
place, so there are opportunities for him to have been exposed before
the contagion was recognized and the capacity to implement
state-of-the-art infection control had been developed in that
facility.
I'll just take one more question from the phone, please.
MODERATOR: The last question comes from the line of Miriam Falco with
CNN. Please go ahead.
QUESTION: Hi. A couple more questions. Number one, do you have any
more clues about why there was a 90 to 10 percent breakdown in
severity of disease, really, that was mentioned either in the MMWR or
in the WHO?
And will these tests that Dr. Hughes was talking about be able to be
used to determine if all of these 62 patients are actual confirmed
cases?
Or is this a lower type of test, just to see what it might lead to for
treatments?
DR. GERBERDING: I'm sorry, I did not understand your first question.
QUESTION: Well, it was either in the MMWR or the WHO report, that 90
percent of the patients get sick but then they recuperate. Ten percent
of the patients have a severe illness and why is there such a
difference in the cases? If you know anything about it.
Could it be that there might be other viruses involved as well?
DR. GERBERDING: Certainly, there could be other cofactors involved
such as viruses or underlying illness, but this is just atypical
pattern for any infectious disease. If you get pneumococcal infection,
many people have completely asymptomatic. Some people get a mild
disease and some people have a full blown, very, very severe illness
from the infection.
So this is a typical pattern for respiratory illnesses, not something
that we're surprised about. In fact if there's any good news in SARS
right now, it's that the majority of patients do appear to recover and
that the death rate is actually lower than what we see with epidemic
influenza, about 3.5 percent of the patients have died from the
illness. That is still a tragic occurrence for the people who are
affected, and their families, and I would never mean to minimize it.
But it is fortunate that it is not even more severe.
With respect to the issue of the diagnostic test, no, as Dr. Hughes
said, we have only had this antibody for about a week, and so the fact
that we've come this far so far means that there's still work to do to
really know is it sensitive, in other words, does it pick up every
case? and is it specific? Is it negative when somebody doesn't have
SARS?
So we've got to do the validation and one way of doing that is to use
the test in the people that we're highly confident have the condition
and compare the results to people with intermediate probability and
then those that we're sure have something completely unrelated, and
that will give us some basis for assessing the reliability of the
test, and that will help us then know whether or not we can use it to
rule in or rule out SARS in the majority of people that we're dealing
with.
So there's a lot of work to be done very fast but I think it's a
remarkable achievement. Dr. Hughes and his team at CDC as well as the
WHO collaborating investigators, should be applauded for the
scientific rigor and the speed with which they have been able to
accomplish so much in so little time.
Thank you for being here today and we look forward to updating you as
we learn more.
(end excerpt)
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Department of State. Web site: http://usinfo.state.gov)