Modeling Lessons Learned
from the SARS Outbreak
Paul A. Dreyer Jr., Ph.D.
Associate Mathematician
RAND
Outline
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Brief Introduction to SARS
Lessons Learned
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Quarantines
Differing Control Measures
Communication
Hoaxes
Conclusions
Introduction to Severe Acute
Respiratory Syndrome (SARS)
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Symptoms
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Initially, high fever and chills, body aches
After 2-7 days, dry coughing (along with possible
oxygen depletion of blood)
Incubation period up to 14 days
Fatality rate about 10 percent (as of 4/25)
Treatment
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CDC recommends treatment for pneumonia
Still working on vaccine, determining vectors
(transmission by ‘close contact’)
SARS coronavirus identified, sequenced
Lessons Learned: Quarantines
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Quarantines seem to be effective,
provided people actually quarantine
themselves
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Individual refusals to quarantine in Toronto
Concerns about stigmatization lead to
concealment of illness
Lack of notification to quarantine
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Taiwan: Personal attendants for inpatient care
may have spread disease
“Ideal” Quarantine Method
Contact w/SARS
Infected Person
Healthy
Person
Symptoms?
No
Notification
Of Possible Contact
Yes
Treatment
and Notification
Yes
No
Symptoms?
Quarantine Until
Contact + 10 Days
“Realistic” Quarantine Issues
Contact w/SARS
Infected Person
Healthy
Person
Symptoms?
No
Notification
Of Possible Contact
Yes
Problems:
- Misdiagnosis
- Non-reporting
Treatment
and Notification
Yes
No
Symptoms?
Quarantine Until
Contact + 10 Days
“Realistic” Quarantine Issues
Contact w/SARS
Infected Person
Healthy
Person
Symptoms?
Problem: 100% coverage
of all contacts difficult
No
Notification
Of Possible Contact
Yes
Treatment
and Notification
Yes
No
Symptoms?
Quarantine Until
Contact + 10 Days
“Realistic” Quarantine Issues
Contact w/SARS
Infected Person
Healthy
Person
Symptoms?
No
Notification
Of Possible Contact
Yes
Treatment
and Notification
Yes
No
Symptoms?
Problem: Refusal
To Quarantine
Quarantine Until
Contact + 10 Days
Lessons Learned: Differing Control Measures
Lessons Learned: Differing Control Measures
United States
- No limitations on travel (travel advisories by CDC)
- CDC activated its Emergency Operations Center
- CDC recommends isolation of SARS-infected individuals
- Basic infection control procedures at hospitals
- CDC distributing health alert cards to passengers
returning from travel in infected regions
Lessons Learned: Differing Control Measures
Canada
- Hospital and school closings
- Checks at airport of incoming passengers
- Quarantines of health care workers
Lessons Learned: Differing Control Measures
Singapore
- $10k fines and jail for breaking quarantine
- Illegal to mislead officials about travel history
- Health Ministry can:
- Quarantine any building
- Destroy any materials suspected to be
sources of infection
Lessons Learned: Differing Control Measures
Taiwan
- 10 day quarantines of all incoming passengers
from SARS-infected areas (+ masks on flights)
- Widespread education of healthcare workers
- Full protective clothing for healthcare workers
(including disposable 2nd layer of clothing)
- Active surveillance of exposed healthcare workers
and contacts of patients (+ quarantines)
Lessons Learned: Differing Control Measures
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Control measures vary from minor (US)
to highly restrictive (Taiwan, Singapore,
China)
Differing control measures should be
reflected in any modeling of global
epidemics
Lessons Learned:
Communication
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Communication methods are imperfect
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Not everyone receives notifications
Not everyone believes the notifications
However, new methods are developing
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Hong Kong hoax
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6 million SMS messages sent to cell phones
Location-based SARS updates via cell phone
Real-time updated websites of SARS information
SARS helpline also used for case detection
Lessons Learned: Hoaxes
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Hong Kong hoaxes
Los Angeles airplane scare
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Hoaxes (or misinformation) cause:
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misallocation of resources
increased fear/confusion in populace
possible health risks (smallpox)
Conclusions
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Epidemiological models should:
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Incorporate realistic quarantine models
Acknowledge differing (and possibly
conflicting) control systems across nations
Consider imperfect information gathering
as well as new communication methods