Vaccines and Related Biological Products Advisory Committee Meeting

July 23, 2009

Novel influenza A (H1N1)Epidemiology Update

Anthony Fiore, MD, MPHInfluenza Division

National Center for Immunizations and Respiratory DiseasesCenters for Disease Control and Prevention

Epidemiology/Surveillance Novel H1N1 – 16 JUL 2009 EDT

Percentage of Visits for Influenza-like Illness (ILI) Reported by the US Outpatient Influenza-like Illness Surveillance Network (ILINet),

National Summary 2008-09 and Previous Two Seasons

† There was no week 53 during the 2006-07 and 2007-08 seasons, therefore the week 53 data point for those seasons is an average of weeks 52 and 1.

0

1

2

3

4

5

6

7

10/4

10/1

811

/1

11/1

511

/29

12/1

312

/27

1/10

1/24 2/

72/

21 3/7

3/21 4/

44/

18 5/2

5/16

5/30

6/13

6/27

7/11

Week Ending Dates

% o

f Vis

its fo

r IL

I

2006-07† 2007-08† 2008-09 National Baseline

Epidemiology/Surveillance Novel H1N1 – 16 JUL 2009

Current Influenza Surveillance – ILINet Regions I-III

2006-07 2007-08 2008-09 Baseline

Region II - NJ, NY

0

2

4

6

8

Week Ending Dates

% o

f Vis

its fo

r IL

I

Region III - DE, DC, MD, PA, VA, WV

0

1

2

3

4

5

6

7

8

Week Ending Dates

% o

f Vis

its fo

r IL

I

Region I - CT, ME, MA, NH, RI, VT

0

1

2

3

4

5

Week Ending Dates

% o

f Vis

its fo

r IL

I

Case Counts (July 16, 2009)

* Most states only testing hospitalized cases. Counts updated weekly

• US case counts*– 40,617 laboratory-confirmed cases– 4,795 hospitalizations– 262 deaths

• Case characteristics– 50% male– Median age

• all cases: 12 years• hospitalized cases: 20 years• deceased cases: 37 years

• Counts of confirmed cases affected by guidance to focus testing on persons at risk for complications or hospitalized

• Aggregate confirmed case reporting began early June; age groups same as for seasonal influenza syndromic surveillance systems

Epidemiology/Surveillance Pandemic H1N1 Cases Rate per 100,000 Population by Age Group

As of 16 JULY 2009 (n=33,112*)

19.5

24.0

6.3

3.6

1.1

0

5

10

15

20

25R

ate

/ 100,0

00 P

op b

y A

ge G

roup

0-4 Yrs 5-24 Yrs 25-49 Yrs 50-64 Yrs ≥65 Yrs

Age Groups

n=19878

*Excludes 7,505 cases with missing ages.Rate / 100,000 by Single Year Age Groups: Denominator source: 2008 Census Estimates, U.S. Census Bureau at: http://www.census.gov/popest/national/asrh/files/NC-EST2007-ALLDATA-R-File24.csv

n=4098

n=6713n=1984

n=439

Epidemiology/Surveillance Pandemic H1N1

Hospitalization Rate per 100,000 Population by Age Group (n=4,395*)

*Hospitalizations with unknown ages are not included (n=300) *Rate / 100,000 by Single Year Age Groups: Denominator source: 2008 Census Estimates, U.S. Census Bureau at: http://www.census.gov/popest/national/asrh/files/NC-EST2007-ALLDATA-R-File24.csv

4.4

2.0

1.0 1.1

1.6

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

0-4 Yrs 5-24 Yrs 25-49 Yrs 50-64 Yrs ≥65 Yrs

Age Group

Hosp

italiz

atio

ns

per

100,0

00 P

opula

tion in

Age

Gro

up

n=799

n= 1417

n= 906

n= 178

n=479

*This value represents an age group-specific average influenza rate from October 1 to April 30 from the 2005-06, 2006-07, and 2007-08 influenza seasons.

**Note: The scales for the 0-23 month and the ≥65 year age groups differ from other age groups.

EIP Influenza Laboratory-Confirmed Cumulative Hospitalization Rates, Spring/Summer 2009

Week

0.0

1.5

3.0

4.5

6.0

15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40

Oct-Apr Seasonal Average*

All Flu Rate (Flu A, FluB, Novel H1N1 combined)

0-23 mo

0.0

1.0

2.0

3.02-4 yr

0.0

1.0

2.0

3.05-17 yr

0.0

1.0

2.0

3.018-49 yr

0.0

1.0

2.0

3.0

15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40

50-64 yr

0.0

1.5

3.0

4.5

6.065+ yr

Rate

per

10,0

00 P

op

ula

tio

n**

Rat

e pe

r 10

,000

pop

ulat

ion

Rat

e pe

r 10

,000

pop

ulat

ion

Epidemiology/Surveillance Distribution by Age Group of Influenza Hospitalized Cases

Emerging Infections Program - Pandemic H1N1 -14 JUL 2009

0

5

10

15

20

25

30

35

40

45

50

< 6 mo 6mo-4 yrs 5-9 yrs 10-17 yrs 18-29 yrs 30-49 yrs 50-64 yrs 65+ yrs

Age group

Per

cent

Seasonal 2007-08 Pandemic 2009*

*April 12 – June 30

Epidemiology/SurveillancePandemic H1N1 Deaths by Age Group

16 JULY 2009 (n=262)

7

43

101

66

23 22

0

20

40

60

80

100

120

Mor

talit

y

0-4 Yrs 5-24 Yrs 25-49 Yrs 50-64 Yrs ≥65 Yrs Unknown

Age Groups

3%

16%

66%

9% 7%

39%

25%

0.17% 0.22%

1.50%

3.33%

5.24%

0

0.01

0.02

0.03

0.04

0.05

0.06

Ca

se F

ata

lity

Ra

tio

0-4 Yrs 5-24 Yrs 25-49 Yrs 50-64 Yrs ≥65 Yrs

Age Groups

n=7

n=101

n=23

n=66

n=43

Epidemiology/Surveillance Pandemic H1N1 Case Fatality Ratio by Age Group

16 JULY 2009 (n=262)

Summary of key epidemiologic findings

• Distribution of cases/hospitalizations/deaths – Highest incidence lab confirmed infections in school age children– Highest hospitalization rates among 0-4 year olds– Hospitalization rates for Apr-Jul 2009 approach cumulative rates for

seasonal influenza among school age children and 18-49 year old adults– Fewest cases but highest case-fatality ratio in older adults

• Distribution of cases by age group is markedly different compared to seasonal influenza– Higher proportion of hospitalized cases in children and young adults– Few cases in older adults

• Similar to seasonal influenza many have underlying medical conditions (~70% among cases hospitalized during April-May)– 30% previously healthy

Future plans for case-countingWHO and United States

• WHO Briefing Note, July 16, 2009– Countries already experiencing community-wide transmission

• can shift focus of surveillance activities to reporting established indicators for monitoring of seasonal influenza activity• are not required to submit regular reports of individual laboratory-confirmed cases and deaths to WHO

– Newly affected countries• report the first confirmed cases• provide weekly aggregated case numbers and descriptive epidemiology of early cases

• United States– Plan for aggregate confirmed case counting to cease– Focus on monitoring hospitalized and deceased cases– Continued monitoring:

• Syndromic surveillance (e.g., ILINet, Biosense)• Population-based surveillance platforms (e.g., Emerging Infections Program, Vaccine Safety Datalink surveillance sites)• Viral surveillance

Reported Cumulative Cases by Country novel 2009-H1N1 – 21 JUL 2009

3,912 conf cases nationwide (13 July)Incidence increasing in most of Australia but declining in Victoria

268 (6.9%) hospitalized

25 (0.6%) ICU

5 deaths (0.1%)

Source: Victoria Infectious Diseases Reference Laboratory (figure); Kaufman et al. MJA 13 July 2009 (case counts). http://www.vidrl.org.au/surveillance/flu%20reports/flurpt09/pdf_files/flu0911.pdf

Victoria state, Australia (Melbourne area) July 12, 2009

Activity in the Americas, 17 July 2009 Influenza A(H1N1) confirmed cases (Source: PAHO)

International Pandemic H1N1 – 17 JUL 2009

Southern Hemisphere Summary

To date any evidence of …

Change in epidemiology? • Different age distribution of cases or severe cases from US? No• Different profile of pre-existing conditions from US? No

Change in timing?• Earlier start to influenza season following nH1N1 introduction? Mixed evidence

Change in health care impact?• Increase in hospitalizations following nH1N1 introduction? Limited evidence • Increase in proportion of hospitalized cases in ICU? Limited evidence

Change in transmission? HH and community attack rates > seasonal influenza? ?

Advisory Committee on Immunization Practices Update

• July 29, 2009 special public meeting (Atlanta)

• Meeting goals– Review epidemiology and virology

– Use scientific data to provide guidance on which groups should be the focus of vaccination efforts

– Provide recommendations on which groups should be prioritized for vaccination first if vaccine is produced and distributed in phases (considerations include epidemiologic data and implementation issues)

– Provide recommendations that would allow the overall vaccination program (seasonal and pandemic) to be most successful

Advisory Committee on Immunization Practices Update

• Meeting presentations– Epidemiology

– Virology

– Implementation

– Communications strategy

– Vaccine availability, formulations and timelines

– Influenza vaccine workgroup discussion summary

• Outcome: ACIP recommendations for use of novel influenza A H1N1 vaccines– Age and/or risk groups

– Prioritization• Need?• Strategy

– Interim recommendations on web

– MMWR publication later in summer

Acknowledgements

• Influenza Division– Joe Bresee (Chief, Epidemiology and Prevention Branch

– Lyn Finelli (Team Lead, Surveillance and Outbreak Investigations)

– Seema Jain

– Sonja Olsen

– Josh Mott

– Many others….

• Hundreds of Federal personnel involved in novel H1N1 pandemic response

• State and Local Health Departments

Pandemic H1N1 Cases by StateRate / 100,000 State Population

As of 16 JUL 2009

South America Situation Report (July 21, 2009)

• Peru

– Community attack rate similar to US (5-10%)

• Argentina

– Higher observed case fatality proportion influenced by early testing practices focusing on identification of severe cases

– Assessment of multiple hospitals in Buenos Aires, Tucuman, and other areas during July suggest that while ICUs have been full, the facilities have not needed to make use of overflow facilities

• CDC staff continue to participate as part of a team that is investigating severe cases, enhancing nationwide surveillance, and establishing population-based surveillance at three sites.

• Chile

– CDC field staff continue to work to enhance national surveillance and establish population-based surveillance in San Felipe