modeling lessons learned from the sars outbreak

Modeling Lessons Learned from the SARS Outbreak

Paul A. Dreyer Jr., Ph.D.Associate Mathematician

RAND

Outline Brief Introduction to SARS Lessons Learned

Quarantines Differing Control Measures Communication Hoaxes

Conclusions

Introduction to Severe Acute Respiratory Syndrome (SARS) Symptoms

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 CDC recommends treatment for pneumonia Still working on vaccine, determining vectors

(transmission by ‘close contact’) SARS coronavirus identified, sequenced

Lessons Learned: Quarantines Quarantines seem to be effective,

provided people actually quarantine themselves Individual refusals to quarantine in

Toronto Concerns about stigmatization lead to

concealment of illness Lack of notification to quarantine

Taiwan: Personal attendants for inpatient care may have spread disease

“Ideal” Quarantine Method

HealthyPerson

Contact w/SARSInfected Person

Quarantine Until Contact + 10 Days

Treatmentand Notification

NotificationOf Possible Contact

Symptoms?

Symptoms?

Yes

Yes

No

No

“Realistic” Quarantine Issues

HealthyPerson





Symptoms?

Symptoms?

Yes

Yes

No

No

Problems:- Misdiagnosis- Non-reporting


HealthyPerson





Symptoms?

Symptoms?

Yes

Yes

No

No

Problem: 100% coverageof all contacts difficult


HealthyPerson





Symptoms?

Symptoms?

Yes

Yes

No

No

Problem: Refusal To Quarantine

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


Canada- Hospital and school closings- Checks at airport of incoming passengers- Quarantines of health care workers


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 besources of infection


Taiwan- 10 day quarantines of all incoming passengersfrom 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)


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 Communication methods are imperfect

Not everyone receives notifications Not everyone believes the notifications

However, new methods are developing Hong Kong hoax

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 Hong Kong hoaxes Los Angeles airplane scare

Hoaxes (or misinformation) cause: misallocation of resources increased fear/confusion in populace possible health risks (smallpox)

Conclusions Epidemiological models should:

Incorporate realistic quarantine models

Acknowledge differing (and possibly conflicting) control systems across nations

Consider imperfect information gathering as well as new communication methods

modeling lessons learned from the sars outbreak

Documents