INFLUENZA DIVISION

U.S. Influenza Surveillance Update, 2007-8 Season

Joseph Bresee MD

Epidemiology and Prevention Branch, Influenza Division, CDC

VRBPAC Meeting

Feb 21, 2008

Gaithersburg, MD

INFLUENZA DIVISION

Seasonal Influenza

• Geographic Spread

• Virus Monitoring

• Mortality

• Outpatient Illness

• Hospitalizations

• Antiviral Resistance

INFLUENZA DIVISION

• 21 states and the District of Columbia reported sporadic influenza activity• 26 states reported no influenza activity ▪ 3 states reported local activity

INFLUENZA DIVISION

• 33 states and the District of Columbia reported sporadic influenza activity• 13 states reported no influenza activity ▪ 4 states reported local activity

INFLUENZA DIVISION

33 states, The District of Columbia and Puerto Rico reported sporadic influenza activity 3 states reported no influenza activity ▪ 9 states reported local activity 5 states reported regional activity

INFLUENZA DIVISION

10 states and Puerto Rico reported sporadic influenza activity 17 states and the District of Columbia reported local activity 17 states reported regional activity ▪ 6 states reported widespread activity

INFLUENZA DIVISION

4 states and Puerto Rico reported sporadic influenza activity 9 states and the District of Columbia reported local activity 26 states reported regional activity ▪ 11 states reported widespread activity

INFLUENZA DIVISION

2 states and the District of Columbia reported local activity 17 states reported regional activity ▪ 31 states reported widespread activity

INFLUENZA DIVISION

1 state and the District of Columbia reported local activity Puerto Rico reported sporadic activity 5 states reported regional activity ▪ 44 states reported widespread activity

INFLUENZA DIVISION

Seasonal Influenza

• Geographic Spread

• Virus Monitoring

• Mortality

• Outpatient Illness

• Hospitalizations

• Antiviral Resistance

INFLUENZA DIVISION

U.S. WHO/NREVSS Collaborating LaboratoriesNational Summary, 2007-08

0

500

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40 42 44 46 48 50 52 2 4 6 8 10 12 14 16 18 20

Week

Nu

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of Is

ola

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Pe

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nt P

ositiv

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A(H3)

A(H1)

A(Unsubtyped)

B

Percent Positive

Since Sept 30-14% of 109,089 specimens tested positive for influenza viruses 83% A 17% B

of 28% of A viruses subtyped:-37% A (H1) viruses-63% A (H3) viruses

INFLUENZA DIVISION

U.S. WHO/NREVSS Collaborating LaboratoriesNational Summary, 2007-08

0

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40 42 44 46 48 50 52 2 4 6 8 10 12 14 16 18 20

Week

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Pe

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nt P

ositiv

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A(H3)

A(H1)

A(Unsubtyped)

B

Percent Positive

In most recent week-34% of 6,889 specimens tested positive for influenza viruses 79% A 21% B

of 23% of A viruses subtyped:

-11% A (H1) viruses-89% A (H3) viruses

INFLUENZA DIVISION

Seasonal Influenza

• Geographic Spread

• Virus Monitoring

• Mortality

• Outpatient Illness

• Hospitalizations

• Antiviral Resistance

INFLUENZA DIVISION

4

6

8

10

12

Weeks

% o

f All

Dea

ths

Due

to P

&I

Epidemic Threshold

Seasonal Baseline

Pneumonia and Influenza Mortalityfor 122 U.S. Cities

Week Ending 02/16/2008

2005 2006

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

200720042008

INFLUENZA DIVISION

Number of Influenza-Associated Pediatric Deaths by Week of Death: 2005-06 season to present

0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

20

05

-40

20

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-44

20

05

-48

20

05

-52

20

06

-04

20

06

-08

20

06

-12

20

06

-16

20

06

-20

20

06

-24

20

06

-28

20

06

-32

20

06

-36

20

06

-40

20

06

-44

20

06

-48

20

06

-52

20

07

-04

20

07

-08

20

07

-12

20

07

-16

20

07

-20

20

07

-24

20

07

-28

20

07

-32

20

07

-36

20

07

-40

20

07

-44

20

07

-48

20

07

-52

20

08

-04

20

08

-08

Week of Death

Nu

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er

of

de

ath

s

INFLUENZA DIVISION

Seasonal Influenza

• Geographic Spread

• Virus Monitoring

• Mortality

• Outpatient Illness

• Hospitalizations

• Antiviral Resistance

INFLUENZA DIVISION

Percentage of Visits for ILI & ARI Reportedby Sentinel Providers and BioSense Outpatient Facilities,

National Summary

0

1

2

3

4

5

6

7

8

20

05

-40

20

05

-44

20

05

-48

20

05

-52

20

06

-04

20

06

-08

20

06

-12

20

06

-16

20

06

-20

20

06

-24

20

06

-28

20

06

-32

20

06

-36

20

06

-40

20

06

-44

20

06

-48

20

06

-52

20

07

-04

20

07

-08

20

07

-12

20

07

-16

20

07

-20

20

07

-24

20

07

-28

20

07

-32

20

07

-36

20

07

-40

20

07

-44

20

07

-48

20

07

-52

20

08

-04

Week

% o

f V

isits fo

r IL

I

%ILI from Sentinel Providers %ARI from DOD/VASentinel Provider Baseline DoD/VA Baseline

INFLUENZA DIVISION

Seasonal Influenza

• Geographic Spread

• Virus Monitoring

• Mortality

• Outpatient Illness

• Hospitalizations

• Antiviral Resistance

INFLUENZA DIVISION

EIP Influenza Laboratory-Confirmed Cumulative Hospitalization Rates for Children Aged 0-4 and 5-17 yrs, 2007-2008 and Previous 2 Seasons

September 30 – February 2, 2008

0

1

2

3

4

5

6

40 41 42 43 44 45 46 47 48 49 50 51 52 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19

Week

Pop

ulat

ion-

Bas

ed R

ate

per 1

0,00

0 C

hild

ren

2005-06, 0-4 years 2005-06, 5-17 years

2006-07, 0-4 years 2006-07, 5-17 years

2007-08, 0-4 years 2007-08, 5-17 years

INFLUENZA DIVISION

Seasonal Influenza

• Geographic Spread

• Virus Monitoring

• Mortality

• Outpatient Illness

• Hospitalizations

• Antiviral Resistance

INFLUENZA DIVISION

Oseltamivir resistance, 2007-8 Influenza Season, U.S.

• 5.7% (27/471) of influenza isolates tested were oseltamivir-resistant– 27 (8.1%) of 312 H1N1 resistant (all with H274Y mutation)– 0 / 76 H3N2– 0 / 83 B

– All regions of the country– No travel history known for any case– No oseltamivir exposure known– Apparent typical clinical illness and severity

• All H1N1 oseltamivir-resistant viruses tested susceptible to zanamivir and adamantanes

• 31% (88/282) influenza A viruses tested resistant to adamantanes– 99% of H3N2 viruses and 7.2% of H1N1 viruses

INFLUENZA DIVISION

A (H1N1) oseltamivir resistance – Europe, Canada, Asia(as of 14 February 2008)

Global – 14% (237 / 1703)

• Europe – 20% (202 / 987) – 13 of 22 countries with resistant H1s

• Asia - 2.1% (7 / 319) – 2 of 7 countries (no resistance in Japan)

• Africa – 0% (0 / 18)

• Americas– Canada – 6% (8/128)– Latin America – 0% (0/9)

WHO dataWHO data

INFLUENZA DIVISION

Oseltamivir resistance – Plans to address

Enhanced Surveillance– Increased numbers of viruses for testing– Collect detailed clinical, epi data on each case

• Standard reporting form that is sent to SHDs

Communications– Talking points and Q&As developed and distributed– Share materials with international and national partners (e.g. WHO,

ECDC, CSTE, APHL, ACIP)– Press briefings

Policy– No change in policy for use of antivirals at this point– ACIP Influenza WG discussed antiviral policy

INFLUENZA DIVISION

Interim Estimation of Influenza Vaccine Effectiveness During the 2007-08 Season

CDC partnered to develop capacity to provide annual VE estimates• This season, will conduct studies to provide VE estimates during the season

Methods• Population: People recommended by ACIP to receive annual vaccination• Outcome: Medically attended influenza diagnosed by RT-PCR• Exposure: Vaccination status confirmed by validated vaccine registry

Status• From Jan 21 through Feb 8, 616 (69%) of 896 eligible patients were tested

– 191 (31%) were PCR-positive for influenza; 144 (75%) of those had influenza A

• Preliminary results indicates vaccine provides – Some protection against infections with influenza A viruses– No protection against infections with influenza B viruses

Plans• Continue enrollment• Type/subtype data pending – for type/subtype-specific analyses• Report of data during the season

INFLUENZA DIVISION

Draft ACIP Agenda: Influenza Session Feb 27, 2008

• Influenza vaccine effectiveness among 6-23 month old children, 2005-6 and 2006-7 seasons

• Influenza vaccine strain selections 2008-09

• Oseltamivir-resistant influenza A (H1N1)

• Expanding influenza vaccination recommendations to include all 5-18 year old children

• Influenza vaccination recommendations, 2008– Vote– VFC Vote