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Three Different Kinds of Influenza Seasonal Influenza “The Flu” Avian Influenza “Bird Flu” Pandemic Influenza “A Pandemic” Related to each other, but public health implications of each is very different

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Page 1: Three Different Kinds of Influenza Seasonal Influenza “The Flu” Seasonal Influenza “The Flu” Avian Influenza “Bird Flu” Avian Influenza “Bird Flu” Pandemic

Three Different Kinds of Influenza

Seasonal Influenza“The Flu”

Seasonal Influenza“The Flu”

Avian Influenza“Bird Flu”

Avian Influenza“Bird Flu”

Pandemic Influenza“A Pandemic”

Pandemic Influenza“A Pandemic”

Related to each other, but public health implications of each is very different

Page 2: Three Different Kinds of Influenza Seasonal Influenza “The Flu” Seasonal Influenza “The Flu” Avian Influenza “Bird Flu” Avian Influenza “Bird Flu” Pandemic

Sequestration completely protected American Samoa, & Australia from the 2nd wave, while

Western Samoa lost 22% of its population

Published Pandemic Mortality Estimates for Selected Countries(Johnson NPAS & Mueller J. Bulletin of the History of Medicine (2002) 76:105-15)

(1918: 28% of current global population. http://birdfluexposed.com/resources/NIALL105.pdf)

USA: 675,000

Bangl./India/Pak.: 18.5 million

Nigeria:455,000

Egypt:139,000

Guatemala: 49,000

Afghan.:320,000

Indonesia:1.5 million

Philip.:94,000

Japan:388,000

Brazil: 180,000

SouthAfrica:300,000

Kenya:150,000

Global Total: 50 – 100 million

(WHO: 40 million +)

Russia/USSR: 450,000

Spain: 257,000

Canada: 50,000

Chile: 35,000

Australia:15,000, in1919 only

British isles:249,000

Page 3: Three Different Kinds of Influenza Seasonal Influenza “The Flu” Seasonal Influenza “The Flu” Avian Influenza “Bird Flu” Avian Influenza “Bird Flu” Pandemic

“In Philadelphia the number of dead quickly overwhelmed the city’s ability to handle bodies.

It was forced to bury people, without coffins, in mass graves and soon began using steam shovels to dig the graves.”

(John Barry, The Great Influenza)

Page 4: Three Different Kinds of Influenza Seasonal Influenza “The Flu” Seasonal Influenza “The Flu” Avian Influenza “Bird Flu” Avian Influenza “Bird Flu” Pandemic

Origin of Pandemic Influenza

Migratory water birds

H 1-16

N 1-9

Domestic pig

Domestic birds

(All human flu pandemics comefrom bird flu by 1of 2 mechanisms)

Page 5: Three Different Kinds of Influenza Seasonal Influenza “The Flu” Seasonal Influenza “The Flu” Avian Influenza “Bird Flu” Avian Influenza “Bird Flu” Pandemic

H5N1’s Global Genetic Roulette Table

Persistence & spread ofH5N1 is historicallyunprecedented for HPAI

(61 countries)

Page 6: Three Different Kinds of Influenza Seasonal Influenza “The Flu” Seasonal Influenza “The Flu” Avian Influenza “Bird Flu” Avian Influenza “Bird Flu” Pandemic

Continuing Widespread H5N1 HPAI = Continuing Serious Pandemic Threat

H5N1 HPAI in poultry is now endemic in several countries, including Bangladesh, Egypt, Indonesia, & Viet Nam.

(28 countries in 2007)

Less H5N1 HPAI in wild migratory birds in 2007/2008 than in 2006

Page 7: Three Different Kinds of Influenza Seasonal Influenza “The Flu” Seasonal Influenza “The Flu” Avian Influenza “Bird Flu” Avian Influenza “Bird Flu” Pandemic

As of June 17, 2008: 383 lab.-confirmed cases in 15 countries, including 241 deaths (Case Fatality: `63%)

Expect human cases in all areas with substantial human exposure to H5N1 HPAI + birds

Page 8: Three Different Kinds of Influenza Seasonal Influenza “The Flu” Seasonal Influenza “The Flu” Avian Influenza “Bird Flu” Avian Influenza “Bird Flu” Pandemic

Three Requirements for a Flu Pandemic:

1. Novel flu virus for humans Yes

2. Ability to replicate in humans Yes & cause illness

3. Ability to pass easily Not Yet from person to person (signaled by growing clusters / outbreaks of human cases)

H5N1 in 1997 & Since 2003:

Page 9: Three Different Kinds of Influenza Seasonal Influenza “The Flu” Seasonal Influenza “The Flu” Avian Influenza “Bird Flu” Avian Influenza “Bird Flu” Pandemic

WHO phases apply to the whole world. Phases 4 & 5 may be skipped

Page 10: Three Different Kinds of Influenza Seasonal Influenza “The Flu” Seasonal Influenza “The Flu” Avian Influenza “Bird Flu” Avian Influenza “Bird Flu” Pandemic

Modes of Person-to-Person Transmission: Close Exposure (maximum 2 meters / 6 feet):

1. Large droplets from coughing, sneezing, & talking, to other’s eyes, nose, or mouth;

2. Contact: direct (hand-to-hand) & indirect (hand-to-surface-to-hand – less common?);

3. ? Airborne / aerosol / droplet nuclei: By aerosol-generating medical procedures & in shared air spaces with poor air circulation? Can remain suspended in air for longer, but NOT long distance or in ventilation systems?

Courtesy of CDC

Page 11: Three Different Kinds of Influenza Seasonal Influenza “The Flu” Seasonal Influenza “The Flu” Avian Influenza “Bird Flu” Avian Influenza “Bird Flu” Pandemic

1918, 1957, & 1968 US & UK Overall Clinical Attack Rates

Range: ~ 23% – 39%. (Slide from Dep. of Health, National Health Service, UK)

0%

5%

10%

15%

20%

25%

30%

35%

40%

45%

1918 NewYork State

1918Manchester

1918Leicester

1918Warrington& Wigan

1957 SELondon

1957 SouthWales

1957Kansas City

1968Kansas City

cli

nic

al

att

ac

k r

ate

(%

)

Page 12: Three Different Kinds of Influenza Seasonal Influenza “The Flu” Seasonal Influenza “The Flu” Avian Influenza “Bird Flu” Avian Influenza “Bird Flu” Pandemic

In Connecticut “local health departments ….. currently note, somewhat incredulously, that, in the

event of Pandemic Flu, they are responsible for:

• “Community quarantine & isolation ....... ;

• “Instituting ….. social distancing ……… ;

• “Mass Care, i.e., taking care of those too ill to be at home ….. when the hospitals have exhausted surge capacity & shut their doors;

• “Mass Fatalities, i.e., collecting large numbers of bodies when the ordinary medical examiner & mortuary processes have collapsed;

• …… “without any assistance from any outside source, as it is assumed that every community is undergoing the same crisis.”

(From a local health department in Connecticut, Feb. 2007)

Page 13: Three Different Kinds of Influenza Seasonal Influenza “The Flu” Seasonal Influenza “The Flu” Avian Influenza “Bird Flu” Avian Influenza “Bird Flu” Pandemic

Pandemic Wave Peak Worker-Absenteeism ~50% (?)+ Long Supply Lines & Just-In-Time Delivery of Goods

= Big Impact on Availability of Goods & Services?

Page 14: Three Different Kinds of Influenza Seasonal Influenza “The Flu” Seasonal Influenza “The Flu” Avian Influenza “Bird Flu” Avian Influenza “Bird Flu” Pandemic

CATEGORIES OF RISK – AVIAN & PANDEMIC INFLUENZA

LivelihoodsLivelihoods

Human HealthHuman Health

Governance &Security

Governance &Security

Social & Humanitarian Needs

Social & Humanitarian Needs

Economic SystemsEconomic Systems

• Food & income loss from poultry deaths, culling & decreased economic activity

• High illness & potentially high death rates• Overstretched health facilities• Disproportionate impact on vulnerable

• Increased demand for governance & security• Higher public anxiety• Reduced capacity due to illness & death

• Deterioration of coping & support mechanisms• Interruption in public services• Quarantine policies

• Trade & commerce disruptions• Degraded labour force• Interruption of regular supply systems

UNSIC

Page 15: Three Different Kinds of Influenza Seasonal Influenza “The Flu” Seasonal Influenza “The Flu” Avian Influenza “Bird Flu” Avian Influenza “Bird Flu” Pandemic

Conclusions (1)Key Unpredictables

1. Will it come from H5N1 or from another subtype?

2. Will we move from Phase 3 to Phase 6 overnight or over months?

3. Will it hit next week, next year, or next decade?

4. What roles will immunization & anti-virals play?

5. How high will mortality be? (1968, 1918, ~H5N1?)

6. How much economic & social disruption?