Influenza: From Basics to Pandemics

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: knoxpanflu@knoxcounty.org