MVP est un partenariat entre l’OMS et PATH

Photos Benoît Lange

Introduction of a Men A conjugate vaccine: How will this change meningitis in Africa?

GEO Meningitis Environmental Risk Consultative MeetingGeneva, 26-27 September, 2007

F Marc LaForce, MD

Confidentiel MVP est un partenariat entre l’OMS et PATH

Country-Level Attack Rate - NIGER

0

10

20

30

40

50

60

1986

1987

1988

1989

1990

1991

1992

1993

1994

1995

1996

1997

1998

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2001

2002

2003

2004

2005

Year

Cas

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0 p

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Confidentiel MVP est un partenariat entre l’OMS et PATH

Outline of Presentation

1. How does Neisseria meningitidis spread in a population?

2. Can this spread be blocked by immunization?

3. Likely public health impact after the introduction of a Men A conjugate vaccine

4. What will not happen

Confidentiel MVP est un partenariat entre l’OMS et PATH

Flow of Neisseria meningitidis Through a Population

Invasion

Colonisation'Recovery'

Acquisition

Transmission

Release Disease

Invasion

Courtesy Drs. Maiden and McLennan

Courtesy Dr. Martin Maiden

Reservoir

Confidentiel MVP est un partenariat entre l’OMS et PATH

Why are conjugate vaccines different?

• In addition to providing individual protection against serious disease, they also reduce asymptomatic carriage

• Reduced carriage lower transmission indirect protection

even unvaccinated individuals in the population are at reduced risk of disease

Confidentiel MVP est un partenariat entre l’OMS et PATH

Invasion

Colonisation'Recovery'

Acquisition

Transmission

Release Disease

Invasion

X

?X

X

X

X

Population effects of MCC vaccinesPopulation effects of MCC vaccinesHerd immmunity or vaccine escapeHerd immmunity or vaccine escape

Courtesy Dr.Martin Maiden

Population Effects of Men C Conjugate Vaccines: The Development of Herd Immunity

reservoir

Confidentiel MVP est un partenariat entre l’OMS et PATH

Flow of colonization in a population where all are susceptible

Number of infectious cycles

Number colonized per infectious cycle

1 3 9 27 81

1 2 3 4 5

27 81

Confidentiel MVP est un partenariat entre l’OMS et PATH

Flow of colonization in a population where two thirds of the population are protected

1 1 1 1 1

1 2 3 4 5

Number of infectious cycles

Number colonized in each infectious cycle

Confidentiel MVP est un partenariat entre l’OMS et PATH

Impact of PNC-7 vaccination in USA

Source: MMWR weekly, 2005 / 54(36);893-897

Confidentiel MVP est un partenariat entre l’OMS et PATH

MenC vaccination in England & Wales

0100200300400500600700800900

1000

1998

/99

1999

/00

2000

/01

2001

/02

2002

/03

2003

/04

2004

/05

2005

/06

2006

/07

2007

/08

2008

/09

Observed cases

Predicted cases (withherd immunity)

Predicted cases (noherd immunity)

Trotter et al, Am J Epi 2005, 162: 89-100

Confidentiel MVP est un partenariat entre l’OMS et PATH

Introduction of Men A conjugate vaccine in Africa

All 1-29 year olds in Burkina Faso to receive

one dose of Men A conjugate vaccine 2008

Campaigns in Mali and Niger 2009

Begin campaigns in Nigeria, Sudan and

Ethiopia 2010

Add more belt countries 2011-2020

Confidentiel MVP est un partenariat entre l’OMS et PATH

Potential Public Health Benefit From a Men A Conjugate Vaccine in Nigeria

Epidemic meningitis in Nigeria

20 000

40 000

60 000

80 000

100 000

120 000

1 4 7 10 13 16 19 22 25 28 31 34 37

Years

Cas

es Nigeria

Over 130,000 potentially preventable cases of meningitis in years 77,78,86,87 and 96

65 70 75 80 85 90 95 00

Confidentiel MVP est un partenariat entre l’OMS et PATH

Potential Public Health Benefit from the Prevention of Men A Epidemics in Mali

Mali

2 000

4 000

6 000

8 000

10 000

12 000

14 000

1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39

Mali

Over 32,000 potentially preventable cases during epidemic years

69,70,81,82,96,97 and 98

65 70 75 80 85 90 95 00

Epidemic meningitis in Mali 1965-2003Cases

Years

Confidentiel MVP est un partenariat entre l’OMS et PATH

Meningitis in Niger

0

100

200

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500

600

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23

Years

Inc

ide

nc

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10

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Niger*

Residual endemic disease

Meningitis in Niger 1981-2003

0

100

200

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400

500

600

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23

Years

Inc

ide

nc

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er

10

0,0

00

NigerEndemicdisease

Epidemic disease

81 85 90 95 00

Potential Impact of a Men A Conjugate Vaccine

81 85 90 95 00

Confidentiel MVP est un partenariat entre l’OMS et PATH

What will not happen

• Acute meningitis cases will not be eliminated

(particularly important in the group less than two years of age where most cases of acute bacterial meningitis are due to Hemophilus and pneumococci)

Confidentiel MVP est un partenariat entre l’OMS et PATH

The Meningitis Vaccine Project