Learning from the 2009 H1N1 Pandemic Response
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Daniel S. Miller MD, MPH
Director, International Influenza Unit Office of the Secretary
Office of Global Health Affairs Department of Health & Human Services
United States
Influenza Is a Significant Global Health Problem
• The influenza virus is CONTINUOUSLY circulating worldwide, infecting humans, birds, pigs, horses, and other animals.
• EVERY YEAR, the influenza virus continues to change and mutate genetically in the multi-species “mixing bowl”.
• EVERY YEAR, influenza sickens hundreds of millions, hospitalizes 3-5 million, and kills 250,000 – 500,000 people worldwide.
• EVERY YEAR, influenza causes large epidemics in temperate AND tropical zones.
• EVERY YEAR, influenza causes large epidemics in high, middle, AND low-income countries.
Global Influenza Surveillance• Global influenza surveillance in clinics,
hospitals, and laboratories around the world monitors the movement of the influenza virus and its genetic changes on a continuous basis.
• Global influenza surveillance is critical to monitoring and early warning of dangerous changes in the influenza virus (e.g. bird flu, emergence of H1N1).
• Global influenza surveillance is a critical tool for risk assessment and global response to influenza epidemics and pandemics.
The Role of Vaccines in Preventing Influenza Epidemics and Responding to Pandemics
• Vaccination is the most effective and cost-effective tool to prevent influenza epidemics.
• Vaccination is important to reduce illness and death in pandemics.
• Current technologies to produce influenza vaccine production are slow, complicated, difficult, and unpredictable.
• A high priority for vaccine production is to demonstrate that a vaccine is effective and safe before administering to a population.
Influenza Pandemics• Periodically, the influenza virus changes suddenly
such that the human population has little or no immunity.
• Global influenza pandemics have occurred for centuries, more recently in 1918, 1957, 1968, 2009.
• Influenza pandemics have been relatively mild (2009) and severe (1918).
• Influenza pandemics WILL occur again and are unpredictable.
• Global activities to improve pandemic preparedness have increased dramatically since 2005.
1. Patient 12. Patient 23. Recognition of potential match between Mexico and US viruses4. US declares a public health emergency5. WHO raises to Pandemic Phase 46. WHO raises to Pandemic Phase 5
Novel Swine-Origin Influenza A (H1N1) Virus Investigation Team. N Engl J Med 2009;10.1056/NEJMoa0903810
Confirmed Cases of Human Infection with Novel Influenza A (H1N1) with Known Date of Illness Onset, United States, March 28 – May 5, 2009
1 2 3 4 5 6
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Baseline (No Intervention)Dynamics
0 500 1000 15000
5,000,00010,000,00015,000,00020,000,00025,000,00030,000,00035,000,00040,000,000
January 1 start date
WorldPoorLower MidUpper MidRich
Day number
Num
ber o
f cas
es
4
0
10
20
30
40
50
60
70
80
90
100
0
2000
4000
6000
8000
10000
12000
14000
Per
cent
Pos
itive
Num
ber o
f Pos
itive
Spe
cim
ens
Week Number
B A(Subtyping not performed)A(H1) A(H3)A(Unable to Subtype) A(2009 H1N1)Percent Positive
Virology 2008-10 Influenza Seasons in U.S.
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Outpatient visits for Influenza like Illness US: selected years
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Influenza Activity October 31, 2009
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Pediatric Deaths Reported During Recent Influenza Seasons
Number of pediatric deaths
More pediatric deaths from flu reported in 2009-2010 season than in previous seasons
Season
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58% of children withunderlying condition
April 15, 2009 – January 5, 2010 (n=2280)
Underlying Conditions and Risk for 2009 H1N1 Hospitalization (Children)
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Underlying Conditions and Risk for 2009 H1N1 Hospitalization (Adults)
84% of adults withunderlying condition
April 15, 2009 – January 5, 2010 (n=4,139)
• 61 million (range: 43 m –89 m) • 274,000 hospitalizations (range: 195,000 to 403,000)• 12,470 deaths (range: 8,870 to 18,300)• 1,280 deaths aged 17 and under (range: 910 to 1,880)
2009 H1N1 influenzaApril 2009 – April 2010
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Seasonality assumptions
0 50100
150200
250300
3500
0.2
0.4
0.6
0.8
1
1.2
New York SFSingapore SFSydney SF
t (assuming t0 = January 1)
Infe
ctiou
snes
s mul
tiplie
r
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