Influenza Hospitalization Surveillance Network

(FluSurv-NET)

Sandra Chaves, MD MSc Influenza Division

Centers for Disease Prevention & Control USA

FluSurv-NET: Description

• Began in 2003-04 influenza season (only children) • Added to the Emerging Infections Program (EIP) network • Not “sentinel sites” but population-based surveillance (with a defined

catchment area/population)

• Collaboration between CDC, state and local health departments, public health & clinical laboratories, academic institutions, and healthcare providers

• Expanded to adult surveillance in 2005-06 season Because threat of avian influenza & pandemic planning

• Expanded to other states (outside EIP) in 2009 pandemic

• Laboratory-based surveillance (relies in influenza testing being done) • Testing is ordered at the discretion of the treating clinician • rRT-PCR, Viral culture, DFA/IFA, Rapid test

• Enhanced surveillance system with weekly interactions between sites and surveillance

hospitals

CT

NY

MD

MI

OH

MN

IA

TN

GA

CO

NM

UT

OR

CA

~9% of the US population (27 million people)

Number of surveillance hospitals per site (Total 268 hospitals)

34

18 17

27

21

5

26

17

13 13

17 14

7

18

12

0

5

10

15

20

25

30

35

40

CA CO CT GA MD MI MN NM NYA NYR OH OR RI TN UT

Characteristics of catchment area hospitals (Total no. hospital=268)

200

48 20

0

50

100

150

200

250

Urban Suburban Rural

Num

ber h

ospi

tals

Community type

Population Density

27 11

7 12

2 14

12 7

16 210

0 50 100 150 200 250

OtherSpecialty Hospital

Psychiatric HospitalPublic Hospital - Other

Public Hospital - IHSHMO/Managed Care/Health Group

Veteran's Affairs HospitalWomen's HospitalChildren's Hospital

General Hospital

Number Hospitals

Hospital Types

131

103

34

0

20

40

60

80

100

120

140

<= 200 beds 201-500 beds 501-1,000 beds

Num

ber H

ospi

tals

Number beds

Hospital Size

Laboratory capacity for influenza testing Survey during 2006-07 vs. 2012-13 influenza seasons

Note: Excludes Public Health Laboratories

0

10

20

30

40

50

60

70

80

90

100

Rapid test PCR/film array viral culture DFA/IFA

% o

f hos

pita

ls p

erfo

rmin

g te

st

2006-07 Hospital labs ( n=231) 2012-13 Hospital labs (n=240)

<30%

Lab-confirmed influenza by type of test used and by site, comparing pre and post pandemic periods

Pre-

pand

emic

Po

st-p

ande

mic

Real time use of data

Calculate population-based hospitalization rates • Weekly data summary posted to interactive online applications

on the FluView website

Characteristics of 2012-13 and 2013-14 hospitalized cases

Number of laboratory confirmed influenza-associated hospitalizations, FluSurv-NET

7517 6307

2409

12371

9619

0

2000

4000

6000

8000

10000

12000

14000

2009-10 2010-11 2011-12 2012-13 2013-14

A(H3N2) B 2009 H1N1

Cumulative rates of laboratory-confirmed influenza hospitalization by season, FluSurv-Net

43.8/100K

35.4/100K

21.7/100K

8.7/100K

Age-specific laboratory-confirmed influenza hospitalization rates, 2013-14 season, FluSurv-Net

87/100K

54/100K

47/100K

22/100K

9/100K

Overall Rate 35.4/100K pop

56% 58%

43% 40%

35%

Impact of FluSurv-NET on understanding influenza seasons

Key public health accomplishments

Assess disease severity and risk factors

Key public health accomplishments (cont.) Investigate "at risk” groups in the population

Key public health accomplishments (cont.) Trends in antiviral treatment uptake

Key public health accomplishments (cont.) Estimate influenza disease burden in US

Key public health accomplishments (cont.) Evaluate the impact of the influenza

vaccination program

Acknowledgements

Lyn Finelli Scott Epperson Lenee Blanton Krista Kniss Rosaline Dhara Desiree Mustaquim Alejandro Perez Michelle Leon Andrea Giorgi Craig Steffens Ashley Fowlkes Julie Villanueva Sophie Smith

Michael Jhung Carrie Reed Alicia Fry Seema Jain Anna Bramley Victoria Jiang Joe Gregg Larisa Gubareva Terri Wallace Xiyan Xu Joseph Bresee Daniel Jernigan Nancy Cox

Thank you!

SChaves@cdc.gov

www.cdc.gov/flu

http://www.cdc.gov/flu/weekly/fluviewinteractive.htm

Extra slides

Surveillance flow

Hospital/ICP list Laboratory log Hospital discharge list Reportable condition

Identification of positive influenza test

Hospitalized patient AND

resident in catchment area No

Yes

Not a case

Case

Review of medical chart and laboratory record

Finalize case report form and data entry

Consult vaccine registry

Contact medical provider

Interview patient/proxy

Data Collected through medical chart review

Patient demographics Admission information

• Reason for hospitalization and transfers • Influenza testing results • Detailed underlying chronic medical conditions

Medical interventions • ICU admission • Mechanical ventilation • Chest radiograph • Influenza treatment

Clinical outcomes • Bacterial and viral co-infections • Discharge summary • ICD9/ICD10 codes

Vaccination history

Strenghts

• Data since 2003 and ongoing collection • Reasonable timeliness • Not nationally representative, but multi-site surveillance • Population-based surveillance – we can derive rates • FluSurv-NET is unique - monitoring influenza disease severity and burden

in the US • Can be a good platform for special studies (e.g., vaccine effectiveness,

antivirals, statin)

Limitations

• We do not include any systematic testing of ill persons – Laboratory-confirmation is dependent on clinician-ordered influenza

testing → biases

• Many physicians still rely on clinical influenza diagnosis – Do not contribute cases to surveillance → underestimation of

cases/rates

Design

• Population-based surveillance system – defined catchment area/population

• Laboratory-based surveillance (relies in influenza testing being done) • Testing is ordered at the discretion of the treating clinician • rRT-PCR, Viral culture, DFA/IFA, Rapid test

• Local surveillance officers build relationship with infection control practitioners from various hospitals:

• Weekly or monthly calls • Check line list of influenza (+) patients • Laboratory logs (where data available electronically) • Request hospital discharge data to check if missing cases • Reportable disease data (in areas where influenza hospitalization is

reportable)

FluSurv-NET Objectives

Primary Objectives • Estimate age-specific hospitalization rates • Describe severe influenza illness & associated complications • Describe temporal trends of influenza hospitalizations by subtype

Secondary Objectives

• Examine risk & protective factors for severe outcomes of influenza • Estimate influenza disease burden • Estimate the impact of the influenza vaccination program

Bi-directional data transmission

Sites

CDC

• Cumulative and age-specific rates calculated by site

• Weekly and monthly feedback reports to monitor data quality

De-identified data transmitted weekly

0

10

20

30

40

50

60

70

80

90

100

0

1,000

2,000

3,000

4,000

5,000

6,000

7,000

8,000

40 50 10 20 30 40 50 10 20 30 40 50 10

Per

cent

Pos

itive

Num

ber o

f Pos

itive

Spe

cim

ens

H3N2v

A(2009 H1N1)

A(H3)

A(Subtyping not performed)

B

Percent Positive

2012 2013 2014 2011

U.S. WHO and National Respiratory and Enteric Virus Surveillance System Collaborating Laboratories,

National Summary, 2011-14

Influenza Surveillance Goals

Describe season • Characterize circulating virus • Onset, intensity, and duration • Severity of illness • Populations at risk

Detect unusual events • Infection by unusual viruses • Unusual clinical syndromes • Large or severe outbreaks • Viruses with pandemic potential

Guide decisions for interventions • Vaccine development and effectiveness • Treatment decisions • Pandemic preparedness planning • Resource allocation • Prevention and control recommendations

National Picture of Activity