Preparing for H1N1 Influenza

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Preparing for H1N1 Influenza Epidemiology of
H1N1 Community Mitigation Marisa DAngeli, MD,
MPH Washington State Dept of Health 8/31/09
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What is Influenza?

• Acute respiratory infection caused by influenza
  virus
• Not the same as having a cold
• Causes fever (usually) with cough and/or sore
  throat
• Other symptoms
• Chills
• Body aches (myalgias)
• Extreme fatigue
• Sometimes diarrhea and vomiting

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Influenza Subtypes

• Influenza A
• Causes human disease (and disease in other
  animals)
• Causes outbreaks
• Mutates and reassorts to create new viruses
• Pandemic potential
• Influenza B
• Causes human disease
• Causes limited outbreaks
• No pandemic potential

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Transmission of Influenza

• Spread by respiratory droplets during close
  contact with sick person
• Spread by touching contaminated objects and
• then touching eyes, nose or mouth
• Can survive on objects for up to
• 48-72 hours

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Seasonal influenza is a serious disease

• Seasonal flu attack rate 5-20
• 36,000 deaths per year in US (severity lt 0.1
  die)
• 200,000 hospitalizations in US
• gt90 of deaths occur in gt 65 year age group
• 50-100 pediatric flu deaths per year
• Certain groups at higher risk of complications
• lt5 years, gt65 years, pregnant, other chronic
  health
• conditions
• Yearly economic impact37 billion
• Vaccine available

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What is an Influenza Pandemic?

• New virus
• People have little or no immunity to it
• Sustained person-to-person transmission
• Novel H1N1 influenza meets these
• criteria

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H1N1 Timeline

• Mar-Apr 2009 reports of severe respiratory
  illnesses in Mexico
• Apr 15 17 surveillance identifies new influenza
  virus in two children in Southern California
• Confirmed to be same virus circulating in Mexico
  (H1N1)
• Washington States first case illness onset April
  19
• May-June spread in US, Canada Mexico, to 74
  countries, 6 continents
• Pandemic declared June 11, 2009

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Summary of Current Situation

• H1N1 causing most flu in US and around the world
• Worldwide
• gt 200,000 lab-confirmed cases worldwide
  (underestimate)
• gt2000 deaths (underestimate)
• In US
• CDC estimates 2,000,000 cases
• gt8500 hospitalizations
• 556 deaths (as of August 27, 2009)
• In Washington State
• 154 hospitalizations
• 14 deaths
• Certain groups at higher risk for serious illness

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Comparison of Seasonal Influenza and 2009 H1N1
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Since school started in US

• Washington State University Aug 21 1 student
  with influenza, Aug 24-28 Student Health Center
  seeing 50 students a day for flu-like illness
• Pueblo, CO Aug 26 47 students ill on first day
  with flu-like symptoms, 25 more sent home
• Flu outbreaks in schools in AL, AZ, KY, MS

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Community Mitigation

• Activities that decrease the opportunity for
  disease transmission
• Isolation (stay home when sick)
• Quarantine (contacts of sick people stay home)
• School closure
• Community social distancing
• Community infection control
• (cover cough, wash hands)

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Why focus on schools?

• Schools are important foci for disease
  transmission
• 40-50 of respiratory virus transmission occurs
  in schools
• Children shed virus longer than adults
• High density in schools
• Behavioral factors
• Children transmit to their families

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Closing schools can decrease flu transmission in
the community

• Israel 2000 2 week teachers strike?22 decrease
  in weekly number of doctor/emergency room visits,
  43 decrease in weekly number of respiratory
  tract infections
• France 1984-2006 when schools closed for
  holidays 16-18 fewer cases influenza,
  extrapolation to pandemic reduction in peak
  attack rate of 38-45
• SARS Hong Kong 2003 schools closed, mass
  gatherings canceled, masks work in public, people
  stayed home as much as possible?viral respiratory
  infections unusually low despite increased
  testing (Cauchemez S. Lancet Infect
  Dis20099473-81)
• Evaluation of closures in US cities during 1918
  flu pandemic showed CM activities were most
  effective applied early, layered and prolonged
  (Markel H. JAMA 2007298(6)644-54)
• Modeling suggests that school closure most
  effective if implemented early in epidemic
  (Halloran ME. Proc Natl Acad Sci USA
  20081054639-44)

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School Closures for H1N1, Spring 2009

• CDC recommended school closure before severity
  was known
• Schools also closed for high absenteeism or many
  sick children at school
• School closure causes social disruption
• Interruption in education and meals
• Child care issues
• Work absenteeism among parents
• Interruption in services
• High economic cost

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Why Close Schools?
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Scenario for Fall 2009

• Influenza virus circulating over the
  summer--unusual
• Vaccine expected mid-October
• Limited supplies
• Requires two doses
• Protective immunity by December?
• Anticipate several months of school with no
  immunity
• Community mitigation will be very important

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New CDC School Guidance 8/09

• Goal
• Avoid school closures
• Keep children healthy
• Prevent severe disease
• Balance preventing severe disease with minimizing
  social disruption

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New CDC School Guidance

• Two levels of interventions
• Less restrictive for severity similar to spring
  2009
• More restrictive for increased severity

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New CDC School Guidance

• For same severity as spring 2009
• Stay home when sick
• Separate ill students and staff until they can be
  sent home
• Hand hygiene and respiratory etiquette
• More frequent cleaning using regular products
• Early treatment for high risk students and staff
• Consider selective school dismissal

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New CDC School Guidance

• For increased severity compared to Spring 2009
• Active screening
• High-risk students and staff stay home
• Students with ill household members stay home
• Increase distance between people at schools
• Extend the period ill persons stay home
• School dismissals

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New CDC School Guidance

• Issues
• Keep high risk students and staff safe
• Continue education and meals for children at home
  sick and during school dismissals
• Childcare issues

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Team Effort

• Federal government
• Dept of Education
• State government
• OSPI
• School districts
• Schools
• Educational Service Districts

• School Nurse Corps
• WA Dept of Health
• Local health jurisdictions
• Families
• Larger community
• Community organizations
• Businesses

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Recommended StrategiesStay home when sick

• Students and staff with flu symptoms should stay
  at home for at least 24 hours after fever is gone
  without the use of fever-reducing medicines
• 3-5 days in most cases
• Avoid contact with others
• Ill persons can shed virus before fever, gt 24
  hours after fever ends, and while taking
  antivirals
• Hand hygiene and respiratory etiquette always
  important
• Longer exclusion period may be appropriate for
  schools with high numbers of high-risk students

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Recommended Strategies Separate ill students and
staff

• Move students and staff with flu symptoms to a
  separate room until they can be sent home
• Have sick person wear a surgical mask when near
  others
• Designate a non-high risk staff to care for ill
  students
• Staff who care for persons with flu symptoms
  should use appropriate personal protective
  equipment

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Recommended Strategies Hand Hygiene and
Respiratory Etiquette

• Wash hands often--especially after coughing or
  sneezing, before eating and after using the
  restroom
• Make time, facilities and materials for adequate
  hand hygiene available to students
• Alcohol-based hand cleaners are also effective
  but less so on dirty hands
• Cover nose and mouth when coughing or sneezing
• Discard tissue after use

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Recommended Strategies Routine Cleaning

• Regularly clean areas and items likely to have
  frequent hand contact and when visibly soiled
• Use usual cleaning agents
• Not necessary to disinfect beyond routine
  cleaning
• Train custodians and others who clean

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Recommended StrategiesEarly Treatment, Selective
Dismissals

• Encourage ill staff and students at high risk for
  complications to seek early treatment
• Selective school dismissals
• May be considered based on population of
  individual school
• Local decision
• Goal is to protect students and staff at high
  risk
• Not likely to have a significant effect on
  community-wide transmission

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If Severity IncreasesActive screening for illness

• Ask about fever and flu symptoms
• Send home people with symptoms of acute
  respiratory infection
• Scan for ill students and staff throughout the
  day
• Send students and staff who appear ill for
  further screening by school-based health care
  worker
• Have ill person wear a mask until sent home, if
  possible

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If Severity Increases Permit high risk persons
to stay home

• School and school boards should consider ways to
  allow people to stay home
• High risk students and staff should make this
  decision in consultation with their healthcare
  provider
• Schools should plan for continuing education for
  these students

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If Severity Increases Students with ill
household members stay home

• School-age children who live with people with flu
  should remain at home for 5 days from the onset
  of illness (quarantine)
• This recommendation is based on timing and
  frequency of household transmission

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If Severity IncreasesIncrease distance between
people

• Explore innovative methods
• Rotate teachers rather than students
• Cancel classes that bring students together from
  multiple classrooms
• Hold classes outdoors
• Move desks farther apart
• Discourage use of school buses and public
  transportation
• Postpone some class trips

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If Severity IncreasesExtend exclusion period for
ill persons

• Ill people stay home for at least 7 days from
  onset of illness, even if symptoms resolve sooner
• If people are still sick after 7 days, they
  should stay home until 24 hours after symptoms
  resolve

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If Severity IncreasesConsider preemptive
dismissals

• CDC will make recommendations based on global and
  national risk assessments
• Goal of preemptive dismissals is to decrease
  community transmission and reduce demand on
  healthcare system
• Time to vaccine-induce immunity may be considered
• Plan for prolonged dismissals and secondary
  effects

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CDC K-12 School Guidance for H1N1

• CDC Guidance for State and Local Public Health
  Officials and School Administrators for School
  (K-12) Responses to Influenza during the
  2009-2010 School Year
• http//www.cdc.gov/h1n1flu/schools/schoolguidance.
  htm
• Preparing for the Flu A Communication Toolkit
  for Schools (Grades K-12)
• http//www.cdc.gov/h1n1flu/schools/toolkit/
• Technical Report
• http//www.cdc.gov/h1n1flu/schools/technicalreport
  .htm

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To report a school closure

• Go to CDC School Dismissal Monitoring System
  website http//www.cdc.gov/h1n1flu/schools/dismiss
  al5Fform/
• Schools and school districts should coordinate
  with their LHJ who should report a school closure
• CDC and DOH ask that school districts post a link
  to the CDC School Dismissal Monitoring System on
  their website and tell schools how to report

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