Pandemic Influenza H1N1: Update and Public Health Response

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Pandemic Influenza H1N1 Update and Public
Health Response

• Zack Moore, MD, MPH
• Respiratory Disease Epidemiologist
• North Carolina Division of Public Health

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Outline

• Flu overview
• The current pandemic
• Background
• Clinical and epidemiologic features
• Surveillance and testing
• Mitigation strategies/control measures
• Pandemic vaccination
• Antiviral recommendations
• Nonpharmaceutical interventions

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The Enemy
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Influenza Types

• Type A
• Epidemics and pandemics
• Animals and humans
• All ages
• Type B
• Epidemics
• Humans only
• Primarily affects children
• Type C
• Mild illness no epidemics or pandemics

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Genetic Changes in Flu

• Antigenic DRIFT
• Continual development of new strains secondary to
  genetic mutations
• A viruses gtgt B viruses
• Seasonal epidemics
• Antigenic SHIFT
• Appearance of novel influenza A virus bearing new
  HA or HA NA
• Influenza A only
• Associated with pandemics

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How Flu Spreads

• Most spread through coughing and sneezing
• Contact transmission also important
• Hand to hand, contaminated surfaces
• Airborne transmission also possible

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Influenza Survival on the Environmental Surfaces

• Hard surfaces 1248 hours
• Cloth/paper 812 hours
• Hands 5 minutes
• Survives longer in low humidity

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Novel Influenza Virus Infection

• Human infection with influenza A virus subtype
  different from the currently circulating human
  subtypes

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Novel Influenza Reporting

• June 2007 Novel influenza A infections added to
  the National Notifiable Diseases Surveillance
  System (NNDSS)
• Goal To facilitate prompt investigation and
  accelerate the implementation of effective public
  health responses

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Pandemic Influenza

• Three Conditions
• Novel virus, all or most susceptible
• Transmissible from person to person
• Wide geographic spread

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Impact of Past Influenza Pandemics
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Infectious Disease Mortality, United States20th
Century
Armstrong, et al. JAMA 199928161-66. Adapted
from CDC slide set
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Pandemic influenza 2nd waves

• 1957 second wave began 3 months after peak of
  the first wave
• 1968 second wave began 12 months after peak of
  the first wave

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1918 Pandemic 2nd Wave
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Pandemic H1N1 Virus

• Reassortment of avian swine human genes
• Origin--? Mexico (Veracruz)
• Current seasonal flu vaccine ineffective
• Sensitive to neuraminidase inhibitors
• Resistant to adamantanes

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• HA denotes the hemagglutinin gene, M the M
  protein gene, NA the neuriminidase gene, NP the
  nucleoprotein gene, NS the nonstructural protein
  gene, PA the polymerase PA gene, PB1 the
  polymerase PB1 gene, and PB2 the polymerase PB2
  gene

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Summary of Events

• March 2830, 2009 2 children from California
  seen for influenza-like illness
• Same influenza A (H1N1) virus not previously
  recognized among swine or human
• April 26, 2009 US Government declares Public
  Health Emergency
• June 11, 2009 WHO declares pandemic
• Infections occurring around the world

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Whats in a Name?

• Swine flu
• Swine-origin influenza virus (S-OIV)
• Mexican flu
• American flu
• H1N1
• Novel H1N1
• 2009 H1N1
• Pandemic H1N1
• Others?

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Where We Are Now

• WHO Phase 6 Pandemic
• Determined by global spread, not severity
• gt160,000 cases confirmed worldwide
• gt400 deaths reported in the US
• Above normal flu activity across NC
• Planning for second wave in Fall
• Likely mixed season with many strains circulating
• Monitoring for increased transmissibility,
  increased virulence

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Pandemic H1N1 Clinical Features

• Most cases uncomplicated, typical influenza-like
  illness (ILI)
• Diarrhea and vomiting might be more prominent
  than with seasonal flu
• As of late July, 2009
• 12 reported US cases hospitalized
• 0.7 reported US cases died

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Clinical Features among NC Cases
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Epidemiologic Features

• Transmission routes similar to seasonal flu
• Primarily droplet
• Controversy re infection control measures
• Data suggest secondary attack rates comparable to
  seasonal flu
• 19 for any acute respiratory illness
• 12 for ILI (fever 100 plus cough or sore
  throat)
• Fewer cases reported among persons 65
• Similar to seasonal H1N1
• Possible immunity from previous exposures?

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Demographic Features of NC Patients
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Novel H1N1 Confirmed and Probable Case Rates in
the US, by Age Group
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Novel H1N1 U.S. Hospitalization Rate per 100,000
Population, by Age Group
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Novel H1N1 U.S. Deaths, by Age Group
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Hospitalizations

• Detailed clinical data presented on gt200
  hospitalized patients (CDC)
• 43 (21) admitted ICU
• 17 (8) died
• Median time from onset of illness to hospital
  admission
• 3 days (range 1-14 days)
• Median length of stay
• 3 days (range 1-53)

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Description of Hospitalized Cases

• 96 female (48), 105 male (52)
• Median age 22 years (range 21 days-86 years)
• Majority with underlying conditions
• Asthma/COPD (32)
• Diabetes (16)
• Immunocompromised (12)
• Chronic cardiovascular disease (11)

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Clinical Features among 201 Hospitalized Cases
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Comparison of Hospitalized vs. Non-hospitalized
Patients in NC
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Novel H1N1 Case Counts
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Confirmed NC Cases by County of Residence
August 12, 2009
Alleghany
Gates
Currituck
Vance
Rockingham
Northampton
Surry
Camden
Caswell
Ashe
Granville
Stokes
Warren
Person
Hertford
Pasquotank
Halifax
Watauga
Perquimans
Wilkes
Alamance
Forsyth
Yadkin
Chowan
Avery
Bertie
Franklin
Mitchell
Guilford
Orange
Nash
Caldwell
Davie
Durham
Alexander
Yancey
Edgecombe
Madison
Tyrrell
Davidson
Dare
Iredell
Martin
Wake
Washington
Burke
Chatham
Randolph
Wilson
Catawba
Pitt
Rowan
McDowell
Buncombe
Beaufort
Greene
Hyde
Johnston
Swain
Haywood
Lincoln
Lee
Rutherford
Montgomery
Cabarrus
Graham
Harnett
Wayne
Henderson
Gaston
Jackson
Moore
Polk
Cleveland
Stanly
Lenoir
Craven
Cherokee
Macon
Transylvania
Mecklenburg
Pamlico
Cumberland
Clay
Hoke
Jones
Sampson
Anson
Richmond
Duplin
Union
Onslow
Scotland
Carteret
Bladen
Robeson
Pender
Columbus
New Hanover
Brunswick
Confirmed Cases, N687 (75 counties)
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Influenza Surveillance

• Not based on individual case reports
• 520 of population affected each year
• No consistency in testing practices
• Relies on
• Surveillance for influenza-like illness (ILI)
• Sentinel Provider Network
• Electronic syndromic surveillance
• Systematic laboratory testing
• Morbidity and mortality monitoring

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Pandemic Flu Surveillance Goals

• Identify and track mutations in viruses/strains
• Describe clinical infections / severity
• Identify severely affected populations
• Detect the onset, duration and geographic spread
  of the pandemic
• Guide interventions
• Provide information to partners

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Flu Surveillance in NC

• Outpatient Surveillance
• Sentinel Provider Network
• Emergency Department Surveillance
• NC DETECT
• Hospitalization Surveillance
• Public Health Epidemiology network
• Testing / reporting of H1N1-assoc
  hospitalizations
• Mortality Surveillance
• Pediatric influenza-associated death reporting
• 122 Cities Mortality Reporting System (1/4 US
  deaths)
• Medical Examiner surveillance

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Percentage of Visits for Influenza-like Illness
Reported by the U.S. Outpatient Influenza-like
Illness Surveillance Network (ILINet)
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Southeastern US
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NY, NJ
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Percentage of Visits for Influenza-like Illness
in ILINet, North Carolina
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NC DETECT
ILINet / SPN
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ED Visits and Admissions for Influenza-Like
Illness in NC
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Laboratory Surveillance
CDC/Katherine Lord
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NC State Lab Influenza Virus Testing Results by
Week, 20082009
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Pandemic H1N1 Testing in NC

• Testing at State Laboratory of Public Health
• Hospitalized patients with ILI
• Patients with ILI seen by sentinel providers
• Algorithm for clinicians at www.flu.nc.gov
• Testing also performed at some commercial and
  hospital-based laboratories

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Rapid Flu Tests and Novel H1N1

• Sensitivity ranges 1070 for novel H1N1
• Low negative predictive value
• Cannot be used to rule out novel H1N1 infection
• High specificity
• Good positive predictive value only if novel H1N1
  prevalent in the community

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Pandemic Flu Testing Take Home

• Treatment and control measure decisions should be
  based on clinical and epidemiologic information
  not on testing

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Pandemic Mitigation Strategies

• Vaccination
• Targeted antiviral treatment and prophylaxis
• Nonpharmaceutical interventions
• Hand hygiene, respiratory etiquette
• Isolation and quarantine
• Social distancing (school dismissal, cancellation
  of large gatherings, teleworking, etc.)
• Mitigation strategies guided by severity of
  illness

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Pandemic H1N1 Vaccine

• Monovalent vaccine
• Separate from seasonal vaccine
• Two doses, 34 weeks apart
• Five manufacturers
• Live attenuated vaccine available (15)
• Clinical trials in progress, evaluating
• Safety / adverse events
• Interval between doses
• Administration with seasonal vaccine

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Pandemic Vaccine Availability

• Considering early roll out in late September
• 20 million doses
• First large bolus expected mid-October
• 100120 doses
• Monthly shipments of 80 million doses
• Total amount dependent on uptake

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Pandemic Vaccine Distribution

• Centralized distribution using McKesson
• Allowing 2x usual number of ship-to sites
• Ancillary supplies shipped with vaccine
• List of pandemic vaccine providers to be compiled
  by Local Health Departments
• 100 dose minimum shipments
• Administration fees allowable
• Aggregate reporting of all vaccine doses
  administered

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Pandemic Vaccine Priority Groups

• Pregnant women
• People who live with or care for children younger
  than 6 months of age
• Health care and emergency services workers
• Persons 6 months through 24 years of age
• People 25 through 64 years of age at high risk
  for complications of influenza

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High Risk for Complications

• Chronic pulmonary, cardiovascular, renal,
  hepatic, hematologic, neurologic, neuromuscular,
  or metabolic disorders
• Immunosuppression
• Persons younger than 19 years of age who are
  receiving long-term aspirin therapy
• Residents of nursing homes and other chronic-care
  facilities

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Priority Groups Smaller

• Pregnant women
• People who live with or care for children younger
  than 6 months of age
• Health care and emergency services workers with
  direct patient contact
• Children 6 months through 4 years of age
• Children 5 through 18 years of age who have
  chronic medical conditions

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Influenza Immunization Coverage Rates Among
Adults, 2002 National Health Interview Survey

• Group Coverage
• gt65 years 65.6
• 50-64 years 34.0
• 18-49 years, high risk 23.1
• Pregnant women 12.4
• Health Care workers 38.4
• 18-49 year old household
• contacts of high risk persons 14.6
• CDC MMWR 2004 53 (No. RR-6)

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Influenza Vaccine Myths

• The vaccine causes influenza
• It cannot
• The vaccine doesnt work
• Vaccine is usually effective against influenza
• I dont need a shot its for the very sick
• Vaccine is not just for the very ill

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Relation of Provider Recommendations and Patient
Attitudes
Dark bars are patients with positive
attitudes toward vaccination. Light bars are
patients with negative attitudes toward
vaccination
Nichol K et al, J Gen Intern Med 1996
11673-677. Adapted from Walt Orenstein
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Antiviral Treatment

• Oseltamivir (Tamiflu) or zanamivir (Relenza)
• 5 day course
• Recommended for
• All hospitalized patients with confirmed,
  probable or suspected novel influenza (H1N1)
• Patients who are at higher risk for seasonal
  influenza complications
• REGARDLESS OF TIME SINCE SYMPTOM ONSET

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Antiviral Chemoprophylaxis

• Oseltamivir or zanamivir
• 10 day course from last exposure
• Consider for
• Close contacts who are at high-risk for
  complications of influenza (including pregnant
  women)
• Health care personnel, public health workers, or
  first responders who have had a recognized,
  unprotected close contact exposure

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Antiviral Resistance

• Widespread oseltamivir resistance in seasonal
  H1N1 during 20082009
• Widespread adamantane resistance in seasonal H3N2
  since 2005
• Adamantanes not active against influenza B
• No widespread oseltamivir resistance among
  pandemic H1N1 isolates
• Antiviral recommendations for Fall might change
  if oseltamivir resistant flu is prevalent

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Isolation Recommendations

• Remain at home until at least 24 hours after
  fever resolves (without fever-reducers)
• 35 days in most cases
• Duration NOT influenced by use of antivirals
• Longer isolation period for health care settings,
  other settings with many high-risk persons
• Practice good respiratory hygiene after return
• Many still shedding gt24 hours after fever

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Community Mitigation

• Recommendations based on disease severity
• Guidance issued for specific settings
• Schools
• Camps
• Workplace
• Health care facilities
• Long-term care facilities
• www.flu.nc.gov and www.cdc.gov/h1n1flu

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Pandemic Flu in Schools Background

• 55 million students, 7 million staff in US
• 130,000 public and private schools
• Dismissals can result in
• Interruption of education
• Difficulty arranging child care
• Parents missing work
• Students missing meals

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School Guidance Goals

• Decrease risk of hospitalization and death
• Minimize disruption of day-to-day social,
  educational, and economic activities
• Goal is NOT to eliminate all transmission of
  influenza in schools
• Might change if severity increases

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School Guidance Similar Severity

• Stay home when sick
• At least 24 hours after fever resolves without
  use of fever-reducing medicines
• Separate ill students/staff
• Emphasize hand hygiene
• Routine environmental cleaning
• Early treatment of high-risk students and staff
• Consider of selective dismissal of schools with
  predominantly high-risk students

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School Dismissal Considerations

• Number and severity of cases
• Local, state, and national levels
• Balance between risk of infection and problems
  that school dismissal can cause
• Different types of dismissal (selective,
  reactive, and preemptive).

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School Dismissal Considerations

• Number and severity of cases
• Local, state, and national levels
• Balance between risk of infection and problems
  that school dismissal can cause
• Different types of dismissal (selective,
  reactive, and preemptive).

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Categories of Dismissal

• Selective
• Most students in the school are high risk
• May close while other schools in the community
  are open
• Reactive
• Used when many students and staff are sick
• Preemptive
• Used early during a flu response to decrease
  spread before many students and staff get sick
• Only considered if severity increases

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School Guidance Increased Severity

• Active screening for illness
• High risk students/staff stay home
• Students with ill household members stay home
• Increase social distancing
• Extend exclusion period to at least 7 days
• Consider preemptive dismissals

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School Dismissal Reporting

• Reporting of all flu-related school dismissals
  requested by CDC
• Report via www.cdc.gov/FluSchoolDismissal

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Health Care Settings NC Recommendations

• Standard precautions
• Gown, gloves, mask, eye protection as warranted
• Droplet precautions
• Surgical mask
• Private room or cohorting
• Strict hand hygiene and respiratory etiquette
• Restriction of ill healthcare workers visitors
• Airborne precautions for aerosol-generating
  procedures

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Whats Next?

• Seasonal and pan flu vaccination campaigns
• Continue enhanced surveillance
• Communicate information to partners
• Work with schools to decrease outbreaks
• Wait for May!

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Acknowledgments

• Some slides adapted from
• Lyn Finelli, CDC
• Walt Orenstein, Emory Vaccine Center
• Julie Casani, NC DPH

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Public Health Resources

• www.flu.nc.com
• www.cdc.gov/h1n1flu
• Questions?
• zack.moore_at_ncmail.net

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Can you get pandemic influenza from eating pork?

• No. The novel H1N1 influenza virus (formerly
  referred to as swine flu) virus is not spread by
  food.
• You cannot get novel H1N1 flu from eating pork
  or pork products. Eating properly handled and
  cooked pork products is safe.