# Presentation: 021610

## SARS Surveillance in the United States:Past Lessons and Preparing for the Future

- Chris Van Beneden, MD, MPH
- Respiratory Diseases Branch
- National Centers for Infectious Diseases
- Centers for Disease Control and Prevention

## Outline

- Epidemiology of SARS: lessons learned
- Surveillance objectives and strategies
- Preparing for SARS surveillance in absence of known activity worldwide
- Surveillance in presence of SARS activity
- Contact tracing
- Key surveillance messages

## Effect of Travel and Missed Cases on the SARS Epidemic

**Spread from Hotel M, Hong Kong**

## Person to Person Spread

**Probable cases of SARS by reported source of infection, **
**Singapore, Feb 25 – Apr 30***** ***

## Total SARS Cases and % Healthcare Workers by Location

**Total No. SARS cases**

**% HCW**

**% HCW**

## Other High-risk Populations: Patients and Visitors

**Greater Toronto Area**
**375 total SARS cases (suspect and probable)**
**107 (28%) patients or visitors**
**Taiwan**
**668 probable SARS cases**
**256 (38%) patients or visitors**

## Second Wave of SARS Outbreak in Toronto

## U.S. SARS cases, 2003

| Type of Case | No. | CoV+* | CoV- | Pending |
| --- | --- | --- | --- | --- |
| Probable | 74 | 8 | 38 | 28 |
| Suspect | 344 | 0 | 169 | 175 |

- *Based on SARS antibody + or – at _>_ 28 days

## Worldwide Outbreak: Key Epidemiologic Features

- Global travel aided spread of SARS
- Healthcare facilities played central role
- Most cases were spread person-to-person
- Vast majority of febrile respiratory infections in U.S. were not SARS

## Outline

- Epidemiology of SARS: lessons learned
- Surveillance objectives and strategies** **
- Preparing for SARS surveillance in absence of known activity worldwide
- Surveillance in presence of SARS activity
- Contact tracing
- Key surveillance messages

## Surveillance: Foundation of SARS Preparedness Plans

- First line of response preparations for potential re-emergence of SARS
- Key components:
- Identification of cases
- Identification, evaluation and monitoring of contacts for potential spread of disease
- Timely reporting and tracking of cases
- Dissemination of updated information to assist in detection and containment of disease
- Real-time data analysis

## SARS Surveillance: Objectives

- Early detection of SARS-CoV cases with or without recognized re-emergence overseas
- Rapid institution of control measures to limit disease spread
- Isolation and infection control
- Contact tracing

## Surveillance Preparedness:  Key Concepts

- Missed cases can lead to many additional cases
- Early case diagnosis and detection can prevent further transmission
- Potential for global spread requires collaboration and communication between healthcare and public health communities
- SARS activity is typically facility- and community-specific

## Surveillance Challenges

- Non-specific clinical presentation
- Difficult to distinguish from other respiratory diseases
- No rapid diagnostic test that can reliably detect infection early in the illness

## Surveillance Opportunities

- Nearly all laboratory-confirmed cases have X-ray evidence of pneumonia by day 7
- History of risk of exposure to SARS is usually present
- Transmission most often occurs during close contact exposures in healthcare settings or households

## Surveillance Strategies: Levels of SARS Activity

- Level of SARS transmission in the community determines risks of exposure
- Absence of known SARS activity worldwide
- Presence of known SARS activity

**“****SARS activity anywhere has global impact”**

## Strategies Surveillance:Impact of level of SARS Activity

- Core surveillance (zero or low-level activity)
- Based on “classic” clinical SARS presentation
- Passive surveillance of high risk exposures
- Rapid reporting and information dissemination
- Enhanced or accelerated surveillance
- Screen broader range of clinical presentations
- Active surveillance of persons in high-risk settings (i.e., hospitals, transportation centers)

## Outline

- Epidemiology of SARS: lessons learned
- Surveillance objectives and strategies
- Preparing for SARS surveillance in absence of known activity worldwide
- Healthcare provider
- State and local public health
- Surveillance in presence of SARS activity
- Contact tracing
- Key surveillance messages

## Will SARS Re-emerge?

- Potential sources of re-emergence
- Animal reservoir
- Humans with persistent infection
- Unrecognized transmission in humans
- Laboratory exposure
- SARS most likely to recur outside U.S.
- Well-established global surveillance is key to recognition of first case

## SARS Surveillance in the Setting of No Known Activity Worldwide

- No epidemiologic links
- Screen for characteristics associated with persons at increased risk for SARS
- Severe disease:  pneumonia requiring hospitalization
- Potential exposure to unrecognized SARS cases
- Travelers
- Healthcare workers
- Clusters of unexplained pneumonia

## Approach to Surveillance and Reporting

**Providers**

**State and local health departments**

**CDC**

*Community*

*Health care facilities*

***Screening***

***Screening***

## Astute Clinicians are 1st Line of Response

- “Have you **traveled** outside the U.S. in the last 10 days?
-       If so, where did you travel?
-       Do you have any close contacts who became ill after traveling outside the U.S.? If so, where did they travel?”
- “Are you employed as a **healthcare worker** with direct patient contact?”
- “Do you have **close contacts** who have been told they have pneumonia?”

**Screen all persons hospitalized for CXR-confirmed pneumonia:**

## If Patient Hospitalized for Pneumonia Answers “Yes” to at Least One Question*:

- Providers:
- Notify state or local health department
- Consider SARS testing if no alternative diagnosis found in 72 hours

***If travel question reveal that the patient or ill contact traveled to a previously affected SARS area **

## If Patient Hospitalized for Pneumonia Answers “Yes” to at Least One Question*:

- Providers:
- Notify state or local health department
- Consider SARS testing if no alternative diagnosis found in 72 hours
**Testing for SARS-CoV should only be done in consultation with public health partners**

***If travel question reveal that the patient or ill contact traveled to a previously affected SARS area **

## Effect of disease Prevalence on Positive Predictive Value (PPV)

**Prevalence of SARS among persons tested**

**PPV**

- Sensitivity of detecting SARS in clinical specimen = 50%
- Specificity of test = 95%

**Prevalence = 1%**
**PPV =** **9%**

**Prevalence = 50%**
**PPV =** **95%**

## State and Local Public Health

- Work with providers to determine if SARS-CoV testing is appropriate
- Review individual reports from providers to further assess likelihood of SARS
- Detect pneumonia clusters
- Identify cases raising further index of suspicion for SARS
- Travelers exposed to person with pneumonia or a healthcare facility
- Healthcare workers with direct patient contact who are part of unexplained pneumonia cluster

## Approach to Surveillance and Reporting

**Providers**

**State and local health departments**

**CDC**

*Community*

*Health care facilities*

**Updated case definitions, lab evaluation, SARS risk factors**

***Screening***

**WHO**

***Screening***

## Outline

- Epidemiology of SARS: lessons learned
- Surveillance objectives and strategies
- Preparing for SARS surveillance in absence of known activity worldwide
- Surveillance in presence of SARS activity
- Contact tracing
- Key surveillance messages

## Surveillance Strategies in Presence of SARS Activity

- Probability that respiratory illness is SARS increases
- Keep up-to-date on global and local transmission
- Consider SARS in patients with early or mild respiratory illness who have specific SARS risk factors:

## Presence of SARS activity: Role of provider

- Continue to screen persons hospitalized for pneumonia
- Screen patients with fever *or* respiratory symptoms for **SARS risk factors **in 10 days prior onset:
- Travel to foreign or domestic location with recent local SARS transmission
- Close contact with a person who has known or suspected SARS infection
- Report all persons suspected to have SARS-CoV infection to public health officials

## Hospital-based SARS surveillance

- Level of response activities should be adapted to the local situation
- Triggers for accelerated surveillance:
- Significant increase numbers of cases
- Documented or suspected unlinked transmission
- Changing transmission patterns

## Hospital-based SARS surveillance Options for Enhanced Surveillance

- Monitor HCWs taking care of SARS patients daily for fever, cough or shortness of breath

- Monitor daily:
- 	  healthcare workers
- 	  inpatients

- Screen all visitors

- Be alert for clusters of pneumonia among HCWs

- Facility with no SARS cases

- Facility with unlinked nosocomial transmission

**Fever, cough, or shortness of breath?**
**SARS risk factors?**

## Role of State and Local Public Health

- Disseminate updated information and guidelines to providers
- Review potential cases reported by providers and evaluate for SARS testing
- Identify and evaluate clusters of unexplained pneumonia
- Report SARS-CoV + cases to CDC immediately
- Conduct contact tracing

## Reporting SARS Cases

- SARS activity anywhere in the world has global implications
- Reporting is critical

## Outline

- Epidemiology of SARS: lessons learned
- Surveillance objectives and strategies
- Preparing for SARS surveillance in absence of known activity worldwide
- Surveillance in presence of SARS activity** **
- Contact tracing
- Key surveillance messages

## Goals of Contact Tracing

- Promptly identify, evaluate and monitor close contacts of SARS cases
- Prevent spread from contacts by monitoring for evidence of infection and the need for isolation
- Critical to disease containment

## Contact Tracing

-  **Rapid** identification and evaluation of all close contacts of SARS cases is **critical** to stopping disease transmission

## SARS Surveillance Preparedness: Key Messages

- Early case detection is critical to prevent disease spread
- Risk of exposure to SARS is key to considering likeliness of diagnosis
- Rapid contact tracing is essential to disease containment
-  SARS response should be adjusted to the extent of disease in local community or facility
- Collaboration between health care providers and public health agencies is critical to SARS preparedness

## SARS Surveillance Plans

- SARS preparedness plans are in progress
- Finalized documents will be distributed via external partners and  CDC website:
**                ****http://www.cdc.gov/ncidod/sars/**

## Acknowledgements

- CDC SARS Preparedness Task Force members
- Representatives from CSTE, ASTHO, NACCHO, APHL, ASM, AHA, NPHIC, HICPAC, APIC, SHEA, IDSA, NIH and other professional organizations