Iowa Influenza Surveillance Network 20072008 Summary

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Iowa Influenza Surveillance Network 2007-2008
Summary

• Meghan Harris, MPH
• Epidemiologist
• Center for Acute Disease Epidemiology
• Iowa Department of Public Health
• Influenza 2008 Fall Teleconferences

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History

• Iowa Influenza Surveillance Network established
  in 2004
• Web-based reporting system
• Partnership with UHL

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Components

• Sentinel providers
• Survey patient population for influenza-like
  illness
• Hospital surveillance sites
• Inpatient population for influenza-associated
  hospitalizations
• School sites
• Absence due to illness
• Long term care facilities
• ILI and vaccination status of cases
• Laboratory
• Percent rapid test positive
• Confirmatory testing, type and strain

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2007-2008 Summary

• Most severe since 2004-2005
• First case confirmed the week of November 10th
• Prolonged peak activity
• Cold winter, record precipitation
• Vaccine mismatch

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Weather

• Harsh winter conditions force people to remain
  indoors and in close proximity to each other
  thereby facilitating spread of influenza and
  other viruses
• Additionally, the flu virus survives well in
  cooler, low humidity conditions1

• 1 Davis GW, Griesemer RA, Shadduck JA, Farrell
  RL. Effect of relative humidity on dynamic
  aerosols of adenovirus 12. Appl Microbiol. 1971
  Apr21(4)676-9.

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Vaccine

• Overall vaccine efficacy was believed to be 44
  percent, and only 58 percent for the most common
  strain- AH3
• Vaccine effectiveness in sub-optimal years ranges
  from 74-79 percent1
• The majority of Iowa laboratory-confirmed cases
  were influenza AH3
• The vaccine had no efficacy against the influenza
  B strain circulating in the U.S. in 2007-2008

1 Centers for Disease Control and Prevention.
Interim Within-Season Estimate of the
Effectiveness of Trivalent Inactivated Influenza
Vaccine --- Marshfield, Wisconsin, 2007--08
Influenza Season. Morbidity and Mortality Weekly
Report, April 18, 2008 / 57(15)393-398.
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Sentinel Surveillance
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Hospital Surveillance
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School Surveillance
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Laboratory Surveillance

• More than 2,000 specimens submitted and tested by
  UHL
• 697 positive (includes tests not performed by
  UHL)
• 243 Influenza A subtype unknown
• 34 Influenza AH1
• 270 Influenza AH3
• 150 Influenza B

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IISN 2008-2009

• Additional influenza epidemiologist
• Expanded hospital surveillance
• Bi-weekly collaboration with regional state
  health partners

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08-09 Vaccine Composition and 07-08 Review

• Meghan Harris, MPH
• Epidemiologist
• Center for Acute Disease Epidemiology
• Iowa Department of Public Health
• Influenza 2008 Fall Teleconferences

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Vaccine Composition

• Influenza surveillance is ongoing year-round
• WHO determines vaccine components in February
  and September
• Vaccine manufacturing takes approximately 6 months

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2007-2008

• A/Solomon Islands/3/2006, H1N1
• A/Wisconsin/67/2005, H3N2
• B/Malaysia/2506/2004

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Mismatch- Influenza A

• Primary mismatch occurred with AH3N2
• 60 of viruses were characterized as
  A/Brisbane/10/2007-like
• Antigenic shift resulted in 44 vaccine efficacy
• Efficacy in sub-optimal years is 74-79
• Majority of influenza A confirmed in IA were H3N2

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Mismatch- Influenza B

• Two distinct antigenic lineages
• Victoria
• Yamagata
• 98 were B/Yamagata similar to B/Florida
• Vaccine component for influenza B was not
  effective in protecting against the common strain

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2008-2009

• A/Brisbane/59/2007, H1N1
• A/Brisbane/10/2007, H3N2
• B/Florida/4/2006-like

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References

• Centers for Disease Control and Prevention.
  Interim Within-Season Estimate of the
  Effectiveness of Trivalent Inactivated Influenza
  Vaccine --- Marshfield, Wisconsin, 2007--08
  Influenza Season. Morbidity and Mortality Weekly
  Report, April 18, 2008 / 57(15)393-398.
• Centers for Disease Control and Prevention.
  Influenza Activity- United States and Worldwide,
  2007-08. Morbidity and Mortality Weekly Report,
  June 27, 2008 / 57(25)692-697.
• www.cdc.gov/flu_vaccine_updates.htm

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Influenza Resources for Laboratorians

• Meghan Harris, MPH
• Epidemiologist
• Center for Acute Disease Epidemiology
• Iowa Department of Public Health
• Influenza 2008 Fall Teleconferences

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Influenza Surveillance

• Submission of specimens is key to detecting
  influenza early in the season
• Rapid test positive predictive values are too low
  until influenza is active in the population

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What to Watch For

• Influenza activity level
• Types and strains circulating in Iowa
• Age groups being impacted
• Outpatient surveillance (morbidity)
• Hospitalization (severity)
• Vaccine efficacy
• Antiviral resistance

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Weekly Report

• http//www.idph.state.ia.us/adper/iisn.asp

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Resources for Laboratorians

• http//www.idph.state.ia.us/adper/flu_healthcare_p
  rovide.asp
• http//www.cdc.gov/flu/professionals/index.htm

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Program Contacts

• Meghan Harris, MPH
• Iowa Influenza Surveillance Network Coordinator,
• Epidemiologist
• Iowa Department of Public Health
• mharris_at_idph.state.ia.us
• 515-281-7134
• Ariel Pleva, MPH
• Epidemiologist
• Iowa Department of Public Health
• apleva_at_idph.state.ia.us
• 515-725-2136
• Sandy Jirsa
• Molecular Biology and Virology
• University Hygienic Laboratory
• Sandy-Jirsa_at_uiowa.edu
• 319-335-4500