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
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
“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)
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)
H5N1’s Global Genetic Roulette Table
Persistence & spread ofH5N1 is historicallyunprecedented for HPAI
(61 countries)
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
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
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:
WHO phases apply to the whole world. Phases 4 & 5 may be skipped
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
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
(%
)
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)
Pandemic Wave Peak Worker-Absenteeism ~50% (?)+ Long Supply Lines & Just-In-Time Delivery of Goods
= Big Impact on Availability of Goods & Services?
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
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?