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Pandemic Influenza
Public Health – Seattle & King County
Pandemic Influenza
The influenza pandemic of 1918-19 killed more
humans than any other disease in a period of
similar duration in the history of the world.
Alfred W. Crosby
America’s Forgotten Pandemic
The Influenza of 1918
Cambridge University Press, 1989
Trends in Infectious Disease Mortality in the United
States During the 20th Century
Armstrong, GL. JAMA. 1999 Jan 6;281(1):61-6.
Pandemic Influenza
1918 Influenza Pandemic
• 20-40 million persons died worldwide, possibly more
• Death rate 25 times higher than previous epidemics
• 500-650,000 deaths in the U.S.: Ten times as many
Americans died of flu than died in WW I
• The epidemic preferentially affected and killed
younger, healthy persons
• The epidemic was so severe that the average life span
in the U.S. was depressed by 10 years
Pandemic Influenza
Percentage of Influenza Deaths by Age Group, 1917-1918
70
60
Percent
50
40
1917
1918
30
20
10
0
<10 10-20 20-30 30-40 40-50 50-60 >60
Age
Crosby. Influenza in America, 1977
2003-4 Outbreak of Highly Pathogenic Avian
(HPAI) Influenza A (H5N1) in Asia
W.H.O. Official Says Deadly Pandemic Is Likely if the
Asian Bird Flu Spreads Among People
By KEITH BRADSHER and LAWRENCE K. ALTMAN
HONG KONG, Nov. 29 - A pandemic of human influenza could kill up to
100 million people around the world in a worst case, a World Health
Organization official said Monday, significantly raising the agency's
earlier estimates of the potential number of deaths in such a catastrophe.
Pandemic Influenza
Outbreak of Avian Influenza A (H5N1) in Asia
Pandemic Influenza
Outbreak of Avian Influenza A (H5N1) in Asia
Pandemic Influenza
Outbreak of Avian Influenza A (H5N1) in Asia
• WHO: H5N1 poses a considerable human public health risk
– Widespread, outbreak not controlled
– Mutates rapidly, propensity to acquire new genes
– Increasing host range
– Directly infects humans
• To-date, at least 60 human cases with 44 deaths from
Vietnam, Thailand, Cambodia
• No sustained person-to-person transmission
• Outbreak not controlled
Phases of an Influenza Pandemic
Phase Level
Definition
0
0
Inter-Pandemic Period: Annual epidemics with 3-4
circulating influenza strains worldwide
0
1
0
2
Initial Report of New Strain in Humans: Novel virus
reported; no clear evidence of person-to-person spread
or outbreak activity.
Novel Virus Alert: Infection in >2 humans confirmed;
ability to spread and cause severe disease questionable.
0
3
1
Human Transmission Confirmed: Person-to-person
transmission confirmed or new virus found in several
countries; at least one outbreak lasting > 2 weeks
Confirmation of Onset of Pandemic: Efficient person-toperson spread with outbreaks in >1 country and evidence of
severe morbidity and mortality
Phases of an Influenza Pandemic
Phase
Definition
2
Regional and Multi-Regional Epidemics: Outbreaks and
epidemics in multiple countries around the world
3
End of First Pandemic Wave: Influenza activity stops in
initially affected regions and continues elsewhere
4
Second or Later Waves: 2 or more waves of infection are
expected to occur within 3-9 months of initial outbreak
5
End of Pandemic: Infection rates return to pre-pandemic
levels, no more large scale “waves” of infection expected.
May take 2 or more years.
Pandemic Influenza
Outbreak of Avian Influenza A (H5N1) in Asia
"We at WHO [the World Health Organization] believe
that the world is now in the gravest possible danger of
a pandemic…"
Dr. Shigeru Omi, the WHO's Western Pacific
Regional Director, 23 February 2005
Pandemic Influenza
Potential Impact of Pandemic Influenza in the U.S.
•
•
•
•
•
•
•
Cannot predict the severity or exact onset of a pandemic
Up to 200 million persons infected
38-89 million persons clinically ill
18-42 million persons require outpatient care
314,00-733,000 persons hospitalized
89,000-207,000 deaths
Economic cost estimated at $71-$166 billion
Pandemic Influenza
Estimated Range of Deaths and Outpatient Medical Visits Due
to Pandemic Influenza in King County by Attack Rate*
Attack Rate
25%
35%
Deaths
578-1,905
809-2,666
Outpatient Medical Visits
178,512-333,315
249,916-466,642
Estimates based on past pandemics suggest demand for inpatient
beds and assisted ventilation may increase by 25%**
*Based on CDC’s FluAid pandemic modeling software
** CDC. National Pandemic Influenza Preparedness Plan
Pandemic Influenza
Pandemic Influenza – Unique Challenges
• Large proportion of population ill and seeking
medical care
• Long duration: weeks – months
• Disruption of vital community services
• Outbreaks may occur simultaneously in many areas
of the U.S., limiting shifts of human and material
resources that occur with other disasters
Pandemic Influenza
Potential Impact of Pandemic Influenza in the U.S.
• Vaccine and antiviral drugs will be in short supply
 6-8 month lag-time needed for vaccine availability
• Healthcare workers and other first responders will be at
higher risk of exposure and illness than the general
population
• Healthcare system will be overwhelmed
• Risk of sudden shortages of key personnel in critical
community services: police, fire, power/utilities,
transportation, air traffic controllers, etc.
Pandemic Influenza
Outbreak of Avian Influenza A (H5N1) in Asia
"I think what we're concerned about is looking at
what's going on in Asia right now with avian flu, and a
very big worry that this is statistically a time bomb
ticking"
"This is a very ominous situation for the globe…"
“..the most important threat we are facing right now."
Dr. Julie L. Gerberding, Director, Centers for Disease
Control & Prevention
Pandemic Influenza
Key Components of Pandemic Preparedness
• Command and control: Decision-making and coordination,
including communication among/between responders
• Surveillance: Recognition & reporting of cases, monitoring
impact on community
• Vaccine and antiviral drug management
• Healthcare system preparedness: delivery of medical care
• Maintenance of essential services: Community emergency
response, provision of social services
• Outbreak containment measures: travel restrictions, school
closings, isolation & quarantine
• Public communication
Pandemic Influenza
Potential Community Measures to Decrease Transmission
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•
•
•
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•
•
Travel advisories/limit travel to affected areas
Limit large public gatherings; close schools
Encourage telecommuting
Limit availability of public transportation
Hand hygiene, respiratory hygiene/cough etiquette
Screening travelers from affected areas*
Quarantine of exposed persons*
Education to allow early identification and isolation of cases*
* Note: Some measures may be most useful early in outbreak and with
strains that are not efficiently transmitted
Public Health – Seattle & King County
Pandemic Influenza Preparedness Planning
Legal Authorities
• State law grants to the Health Officer broad authority
to take measures necessary to protect public health
– “The local health officer, acting under the direction of the
local board of health . . . shall . . . control and prevent the
spread of any dangerous, contagious or infectious diseases
that may occur within his or her jurisdiction.” RCW
70.05.070(3)..
• The Health Officer’s powers are not contingent on a
proclamation of an emergency by the Executive or
Governor.
Public Health – Seattle & King County
Pandemic Influenza Preparedness Planning
Legal Authorities
During a pandemic flu outbreak, the Health Officer
will evaluate the need for:
–
community outbreak containment and
response measures
– Temporary reorganization of medical
services (cancellations of elective hospital
admissions and redirection of available resources)
Pandemic Influenza Planning Goals
• Limit sickness and death
• Maintain continuity of essential services
• Minimize social disruption
• Reduce economic losses
Pandemic Influenza Preparedness
Activities Underway
• Educating and informing:
– First Responders
– Emergency Managers
– Elected Leaders
• Coordinating with hospitals and health care providers
Pandemic Influenza Preparedness
Activities Underway
• Identifying protective measures that may be necessary
and the circumstances for their use
• Enhancing capabilities to rapidly vaccinate large
populations
• Enhancing our capabilities to communicate information
to the public
Pandemic Influenza Preparedness
Key Steps for Local Governments
Business Continuity Planning
1. Prioritize critical functions
–
Life, Health, Safety (Police, Fire, EMS, Public Health, Hospitals)
–
Identify functions that support life, health and safety
actions (Communications, data management, facility operation, payroll)
–
Identify functions that are critical to the mission of an
agency
Pandemic Influenza Preparedness
Key Steps for Local Governments
Business Continuity Planning
2. Identify staff needed to carry out critical functions
3. Identify functions that could be suspended
4. Build depth through cross training
5. Plan for alternative work schedules
6. Explore telecommuting capabilities – large scale
Pandemic Influenza Preparedness
Key Steps for Local Governments
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Ensure local emergency managers coordinate with
Public Health and local hospitals
Engage local businesses and large employers
– Educate, inform, support
Involve elected leaders - identify actions they may
take in response to a pandemic event
Pandemic Influenza Preparedness - Next Steps
•
Focus on health system resiliency and expanded
capacity
•
Support business continuity planning
•
Brief elected leaders
•
Conduct training and exercises