Influenza: From Basics to
Pandemics
Why Worry? Why Plan?Influenza is Serious!
•Annual deaths: 36,000
•Hospitalizations: >200,000
Who is at greatest risk for serious complications?Persons 65 and older
Persons with chronic diseasesInfants
Pregnant womenNursing home residents
Influenza= Flu
Respiratory infection Rapid onset of Fever, Chills, Body aches, Sore
throat, Non-productive cough, Runny nose, Headache
Takes 1- 5 days from exposure to beginning of symptoms
Contagious maximum 1-2 days before to 4-5 days after onset of symptoms
Peak usually occurs December through March in North America
Influenza Virus: How it spreads
Close contact (<6 feet) with sick person who is coughing or sneezing by way of droplets
ORTouching a surface contaminated by respiratory secretions and getting the virus into mouth, nose or eyes.
Influenza Epidemic Pattern
Epidemic: Higher than normal number of cases of a disease in a community Also called “outbreak”
Abrupt onset in a community: overall attack rate 10-20%
Sharp peak in 2- 3 weeks, lasts about 5-6 weeks
Influenza Epidemic Pattern
First sign: Increased # children with febrile respiratory illness
Followed by: increased hospitalization rate for pneumonia/COPD/CHF/croup
Absenteeism a late indicator
Influenza background
Flu strains typically found in many mammals Birds and swine common hosts for what
ultimately become human flu viruses
Flu hosts usually develop an immunity to the virus after infection
How does the virus survive?
Minor mutation in flu virus is referred to as drift.
A much bigger change is referred to as a shift Shift: Major change = new subtype =
Pandemic potential
Pandemic – An epidemic that spreads around the world
Influenza types
Type A (Party Girls) Animals and humans More versatile, more virulent Epidemics and pandemics All ages
Type B (DAR) Humans only Milder epidemics Primarily affects children
Key Influenza A Viral Features
Hemagglutinin (HA)
Site of attachment to host cells
• Antibody to HA is protective
Neuraminadase (NA)• Helps release virions from
cells• Antibody to NA can help
modify disease severity
HA
NA
Two surface glycoproteins (major antigens)
The Pandemic Influenza Cycle
Rapid transmission worldwide Multiple waves of disease over a 18-24 month
period Occurrence of cases outside usual season
High attack rate and high death rate All age groups, especially young adults
Cycles every 10-40 years Last pandemic was mild-1968
How does the virus survive?
Minor mutation in antigens of flu virus is referred to as drift.A much bigger immunologic change (mutation) is referred to as a shift Shift: Major change = new/novel subtype =
Pandemic potential
Pandemic – an infectious disease occurring over a wide geographic area targeting a high percentage of the population
HumanHuman virusvirus
ReassortantReassortantVirus – Virus –
1957, 19681957, 1968
Non-humanNon-humanvirusvirus
DIRECT - 1918DIRECT - 1918
Mechanisms of Antigenic Shift
The Pandemic Influenza Cycle
Rapid transmission with worldwide outbreaks; multiple waves of disease over a 18-24 month period
Occurrence of cases outside the usual season
High attack rate for all age groups, with high mortality rates, esp for young adults
Cycles 10-40 years. Last pandemic was mild, 1968
Influenza Pandemics in the 20th Century
A(H1N1) A(H2N2) A(H3N2)1918: “Spanish Flu” 1957: “Asian Flu” 1968: “Hong Kong Flu”
20-40 m deaths
675,000 US deaths
1-4 m deaths
70,000 US deaths
1-4 m deaths
34,000 US deaths
Credit: US National Museum of Health and Medicine
Impact of Past Influenza Pandemics/Antigenic Shifts
Pandemic, or Antigenic Shift
Excess Mortality Populations Affected
1918-19Spanish Flu
500,000 Persons <65 years
1957-58Asian Flu
70,000 Infants, elderly
1968-69Hong Kong Flu
36,000 Infants, elderly
1977-78Russian Flu
8,300 Young (persons <20)
The social and medical importance of the 1918-1919 influenza pandemic
cannot be overemphasized
About half of the 2 billion people living on earth in 1918 became infected
At least 20 million people died
1918 Spanish Flu: United States
20 million flu cases were reported and almost ½ million people died
“It is impossible to imagine the social misery and dislocation implicit in these dry statistics.” America’s Forgotten Pandemic, Alfred Crosby
H5N1 “Avian” flu
The current strain of avian flu, H5N1, represents a major shift
When the major shift “waits” 50-75 years:Community has very little or no
immunity/protectionEntire population is a ripe target
20
• Current outbreaks for H5N1 Avian Flu in poultry and birds are largest ever
documented• Duration of outbreak creates potential
for genetic change that could result in person-to-person transmission
Nations With Confirmed Cases H5N1 Avian Influenza (July 7, 2006)
Avian Influenza A Viruses
Wild waterfowl are natural reservoirWild waterfowl are natural reservoir Infect respiratory and gastrointestinal tracts of birdsInfect respiratory and gastrointestinal tracts of birds Usually do not cause diseaseUsually do not cause disease Genetic re-assortment is frequentGenetic re-assortment is frequent
Viruses are present in Viruses are present in respiratory secretions, fecesrespiratory secretions, feces
Can survive at low temperatures Can survive at low temperatures and low humidity for and low humidity for days to weeks, and in waterdays to weeks, and in water
H5N1 in Humans – 2003-2006
As of June, 2006: 256 cases, 152 deaths Ten countries Millions have been exposed to poultry 50% cases in persons <20 years old 90% cases <40 years old
Sporadic, with occasional clusters All lived in countries with poultry outbreaks
Most had touched or handled sick poultry
Few cases of probable, limited human-to-human transmission
Global Status of Current Pandemic Threat
World Health Organization (WHO) defines 3 major periods (broken into 6 phases) of increasing human infection with new flu virus: Interpandemic (no human infection)
Pandemic Alert (limited human infection)
Pandemic (widespread human infection)
Presently at Pandemic Alert (Phase 3) “Isolated human infections with a novel influenza strain
[H5N1] with no (or rare) person-to-person transmission”.
“The pandemic clock is ticking, we just don’t know what time it
is”
Assumptions About Disease Transmission
No one immune to virus 1 out of every 3 people will become ill
People may be contagious up to 24 hours before they know they are sick Most will become ill 2 days (range 1-10) after exposure
People are most contagious the first 2 days of illness Sick children are more contagious than adults
On average, each ill person can infect 2 or 3 others (if no precautions are taken)
Social and Economic Impact Assumptions
Absenteeism At the peak of a 6-8 week wave, ~40% of employees may
be absent Illness Caring for sick family member Fear
Hospital demands Estimated >25% more patients than normal needing
hospitalization Hospitals will not be able to take everyone they normally
would!
Federal or other outside volunteers and resources?
Volunteers will be needed
in their own communities
Communities should plan to respond with their own resources,
not rely on outside help
HHS Estimated Medical Burdenin Tennessee
(Pop: 6 million) Characteristic Moderate Severe*
Illness (30%) 1.8 million 1.8 million
Outpatient Care 900,000 900,000
Hospitalization 17,300 198,000
ICU Care 2,575 29,700
Mechanical Ventilation
1,300 14,850
Deaths 4,180 (0.2%) 38,060 (2%)
*HHS Recommends that states plan for severe scenario
Estimated Medical Burden in Knox County
Characteristic Moderate (0.2%) Severe (2%)
Illness (30%) 119,000 119,000
Outpatient care 59,500 59,500
Hospitalization 1,190 11,900
ICU (15% hosp pts) 180 1,800
Mechanical ventilators (50% ICU pts)
90 900
Deaths 240 2,380
HHS Assumptions: Objectives of Pandemic Planning &
ResponsePrimary objective: Minimize sickness and death
Secondary objectives: Preserve functional society
Minimize economic disruption
There is not complete consensus on the proper order of these assumptions!
Surveillance:
Traditional responsibility of Department of HealthSyndromic Surveillance: Monitor 911 calls, emergency department visits, doctor visits, and school absenteeismSentinel health care providers: Testing and active surveillance for patients with ILICDC planning additional national surveillance activities
Disease Control:Early Stage
Initial objective: slow spread of disease
Isolate sick patients
Quarantine exposed healthy persons. Housing, health care, food, psychological,
spiritual, needs must be metLegal measures possible but will rely on
voluntary cooperation
Once beyond initial cases,
shift strategy to
“Stay home when you are sick”
Disease Control: Social Distancing
Once pandemic begins in US, gatherings of >10,000 people subject to cancellation
During local waves: Suspend discretionary public gatherings of >100
School and Daycare ClosureKey to slowing spread is to disrupt nodes of intense transmission
Preschool through 12th grade are such nodes Attack rates of 40% possible in schools during
ordinary flu season
Pre-emptive school/large daycare closure is central component of proposed federal strategy
School and Daycare ClosureKey to slowing spread is to disrupt nodes of intense transmission
Preschool through 12th grade are such nodes (Attack rates of 40% possible in schools during ordinary flu season)
Pre-emptive school/large daycare closure is central component of proposed federal strategy
“Respiratory hygiene”, “Cough etiquette”, “Good health manners”
Infection Control:“Cover Your Cough”
Survival @ 82oF, 35-49% humidity (longer if lower temp, lower humidity) 48h on hard non-porous
surfaces 8-12h on cloth, paper, tissue Susceptible to EPA registered
disinfectants
Transmission: Droplet- surgical masks protective
Infection Control Assumptions
Airborne transmission (less common, but much more infective: 10-100 x vs. droplets). Surgical masks NOT protective
Aerosol-generating procedures (e.g., intubation, suctioning, nebulizer treatment, bronchoscopy, intubation, BiPAP, CPAP): N95 respirators should be used
Infection Control Assumptions
What About Vaccine?
Production minimum 6 month process: Process requires eggs (93 million!) but virus is lethal to birds Unlikely to be available before 1st pandemic wave
HHS priority groups Military and Vaccine manufacturers Healthcare workers with direct patient care Persons at highest risk for complications
Two doses needed for protection
What About Antivirals?
TamifluAnti-viral agent, currently in short supplyCould be used in one area of world to contain first human outbreakResistance describedShould be used within 48 of infectionUnlikely to markedly affect course of pandemic
Tamiflu ≠ Preparedness
Vaccine/Antiviral Distribution
Prioritization of personnel : based on level of patient contact
Vaccine will be administered by public health personnel over months
Prioritization determined by Feds and may change
Guidance for Planning
Because resources will be limited…
Contingency planning should include: Planning for absenteeism: ~40% Hygiene products and
education in the workplace Supply shortages Home offices for critical
personnel Sick leave policies compatible
with state recommendations
Internal and External Communication networks
Detailed communications plans needed: Internal- Ensure employees know panflu policy,
communications plan, their specific role, esp in surge capacity
External- POC with Health Department Info via KCHD website, Broadcast FAX, Email, Media
Coordinate with like organizations
to develop/coordinate emergency plans
Communicate with other facilities affected by yours
Infection Control:
Education
Signage to educate personnel and patientsAdequacy of surgical masks for patient contact not involving aerosolization proceduresPossibility of using surgical masks over reusable N95s as well as goggles/face shields for high-risk proceduresEstablishing regularly scheduled environmental cleaning
Infection Control:Using PPE
Follow protocol for donning and removing PPE• Provide tissues &
instructions when to use them: proper disposal; importance of hand- hygiene
Provide hand hygiene
materials (>60% alcohol)
Surveillance for those at work
Develop screening for employees with flu-like symptoms
Develop sick leave policy specific for panflu: liberal and non-punitive
Determine when ill employee may return to work
Sick Leave policy
Liberal and non-punitive
Staff who become ill at work
Recovering staff- when to return
Symptomatic but functional staff-allowed to work?
Reassignment of personnel at increased risk for flu complications
Offer annual flu vaccine
Surge Capacity: Staffing Shortages
Identify minimum number employees and categories required for essential operations
Temporary help
Cross train employees
MOAs with other facilities
Surge Capacity: Supplies
Estimate needs for
consumable resources
Primary Plan & Contingency PlanDetailed procedures for supply acquisitionNormal channels exhausted: have a back-
up
Workforce Support
Psychological and physical strain on personnel responding in emergency situationPsychological stress for families Plan for your staff to have adequateSleep, foodAccess to psychological
and spiritual support
Pandemic flu today
Despite . . . Expanded global and national surveillance Better healthcare, medicines, diagnostics Greater vaccine manufacturing capacity
New risks: Increased global travel and commerce Greater population density More elderly and immunosuppressed More daycare and nursing homes Bioterrorism
Steps YOU can take
Practice good personal hygiene:Avoid hand contact with your mouth, eyes,
and noseWash hands regularly and often Use paper towels to turn off the faucet and
open the restroom doors
Steps YOU can take
Carry a supply of hand sanitizing gel – use it regularly
60%-95% alcohol-based sanitizer
Cover your cough
Steps YOU can take
Get a flu vaccination when offered
When flu season arrives- avoid contact with infected people, limit social activity
Consider wearing surgical mask and/or disposable gloves when in public
Steps YOU can take
Be aware in public of potentially infected surfaces Check-out counters, door knobs,
pay phones
Regularly disinfect commonly used surfaces
1:10 bleach solution EPA registered disinfectant
Steps YOU can take
Illness preparation: Maintain supply of electrolyte
drinks (Gatorade) Antipyretics (Tylenol) Prescription medications
Stock up on water and food- one week’s supply Minimum: One gallon per
person per day Store in plastic, not glass
Food that won’t spoil
Steps YOU can take
Make plans for child care in the event schools close 6-8 weeks
Plan for eldercare/pet care
Family Planning is Essential
Good advice for any disaster, not just pandemic influenza!!!
See Family Planning ChecklistsPandemicflu.govRedCross.orgReady.gov
Resources
PandemicFlu.govCDC.gov/flu/avianRedCross.orgwww.nyhealth.govKnoxcounty.org/health: if you want to be put on “Pandemic Alert Email” list
For questions regarding pandemic influenza planning, please call 215-5171 or email: [email protected]