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2009 (Pandemic) H1N1 Influenza Virus

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  1. 2009 (Pandemic) H1N1 Influenza Virus Washington State Department of Health Based on slides from: Anthony A Marfin Marcia Goldoft

  2. Outline • Influenza, the illness • Seasonal vs. pandemic influenza • Current pandemic situation reports • What to expect this fall / winter • Public health response

  3. What Is “Influenza-like Illness” (ILI)? • Virus causing two respiratory disease syndromes • ILI (upper respiratory tract) • Fever plus cough or sore throat • Lots of other symptoms • Severe acute respiratory illness (SARI) • ILI plus SOB, tachypnea, hypoxia • Lower lung involvement • ILI or SARI not only from influenza

  4. You can have a mild case of influenza,but influenza is not a mild illness.

  5. Seasonal Influenza Viruses • Seasonal A H3N2, A H1N1, and B viruses spread by respiratory secretions • Toddlers, children, and adolescents transmit readily • Most cases in these age groups • Very young/old persons at risk forsevere illness • Most deaths in these age groups • Vaccine is the best and most cost-effective control

  6. Each year, seasonal flu accounts for: 36,000 deaths 200,000 hospitalizations 20,000,000 ILIs (may or may not be medically attended) ? Asymptomatic infections

  7. Seasonal vs. Pandemic Influenza • Every year, viruses change a little (“drift”) • Seasonal flu epidemics each winter • Quickly adjust vaccine annually • Rarely, viruses change a lot (“shift”) • Entirely new viruses so nobody immune • Spread easily among non-immune humans • Worldwide epidemic transmission (pandemic) • Develop new vaccine over many months

  8. Pandemic Influenza 1918 Estimated 675,000 deaths / 105 million US population (0.6%) Public health challenges compared to now: war troop transport, lack of health care, lack of public health planning, interrupted public services (garbage, mail, telegraph, telephone) Deaths due to infectious diseases, United States 1900-1994 Philadelphia was overwhelmed by the number of dead. Burials were done without coffins, eventually in mass graves dug by steam shovels. 1918 influenza pandemic

  9. Influenza Deaths, 1918 Compared to 1915 9

  10. Current Situation United States and Washington Beginning April 2009

  11. H1N1 2009 Influenza Virus Pedigree 2009 Human A/H1N1 (2009-??) Eurasian swine A/H1N1 (1979-present) ? Human “seasonal” A/H3N2 (1968-present) Avian influenza viruses “Triple reassortant” Swine A/H1N2 (1998-present) North American swine A/H1N1 (1918-present) Human seasonal A/H1N1 (1977-present)

  12. 2009 H1N1 Influenza • Entirely new virus so nobody immune • First identified in California and Mexico, April 2009 • Initial investigations → virus found in many states • Summer 2009, worldwide spread • Globally, most flu cases due to 2009 H1N1 • Flu pandemic declared by WHO June 2009 • Flu cases in U.S. and Washington continued through summer into fall (unusual) • Severe cases and deaths

  13. Risk for severe infections with 2009 H1N1 Lung disease (asthma, smoking, COPD) Diabetes Pregnant Heart disease Other chronic medical conditions Neuro-developmental disease in children 2009 H1N1 Influenza

  14. Flu virus testing in typical flu season in early 2009 with mix of seasonal H1N1, H3N2, Anot typed, and B viruses.

  15. New H1N1 virus in April.

  16. Percentage of ER Visits for ILI by CDC Week, Western Washington 2009 October May

  17. What Can We Expect This Winter? More cases of flu than in typical years, particularly in younger ages Absenteeism due to own or family illness More deaths because more cases More deaths in younger ages because more cases in younger ages With seasonal flu, 90+ % deaths are ≥ 65 years With H1N1 flu, 90+ % death are < 65 years

  18. Public Health Response

  19. Components of Response • Surveillance • Community Mitigation • Healthcare Planning • Communication • Continuity of Operations Planning

  20. Influenza Surveillance in Washington Mandatory reporting in Washington Died Hospitalized Sentinel physicians, aggregate lab data, syndromic surveillance Medically attended ILI Community survey, school absenteeism ILI cared for at home Asymptomatic

  21. Community Mitigation Interventions that lessen the impact of a pandemic Community mitigation can include: Non-pharmaceutical interventions Isolation (ill) Quarantine (exposed to ill) School Closure Community Social Distancing Community Infection control Pharmaceutical Interventions Antivirals Vaccine

  22. 2 1 3 Goals of Community Mitigation Delay outbreak peak Pandemic Outbreak: No Intervention Decompress peak burden on hospitals/infrastructure Diminish overall cases and health impacts Daily Cases Pandemic Outbreak: With Intervention Days Since First Case

  23. What you can do • Wash your hands. • Cover your cough. • Don’t touch your eyes, nose and mouth • Try to avoid contact with sick people. • Make a family plan. • Stay home if you’re sick. • Get vaccinated (flu and maybe pneumococcal).

  24. Current CDC and DOH Community Mitigation Strategy for 2009 H1N1 • H1N1 not severe enough for widespread community social distancing (e.g., school closures) • Protect overall public health by: • Reducing community transmission • Minimizing severe cases • Preventing social disruption • May change – influenza is unpredictable! • Still need to prepare for a major epidemic like 1918

  25. Antiviral and Vaccine Distribution • DOH received antivirals and N95 masks from the Strategic National Stockpile (SNS) this spring • DOH receiving H1N1 vaccine this fall as available • DOH distributed antivirals and vaccine to LHJs • Monitoring the usage of antiviral medications • Usage has rapidly increased over the past few weeks

  26. ACIP Target Populations for H1N1 Vaccination* • Pregnant women • Household contacts and caregivers for children younger than 6 months of age • Healthcare and emergency medical services personnel • All people from 6 months through 24 years of age • Persons aged 25 through 64 years who have health conditions associated with higher risk of medical complications from influenza *MMWR 2009;58:1-8

  27. Dell Children's Medical Center in Austin is seeing hundreds of patients a day with flu-like symptoms and is preparing triage tents to handle the volume. Hospitals are screening and limiting visitors. http://www.statesman.com/news/content/news/stories/local/2009/09/22/rbz-Hospital-Flu-Tents-05.html

  28. Communication • Complex messages need to be communicated to the public and healthcare providers • Complex public messages • Disease severity • Seeking medical care • Vaccine safety • Complex healthcare provider messages • Purpose of the Public Health Laboratories • Treatment recommendations

  29. COOP Identify who will be affected Plan for workforce reduction and support of workers Cross-training for critical jobs Consider flexible work schedules Reduce spread of influenza Promote cough etiquette and hand cleaning Promote vaccination (flu and pneumococcal) Provide routine environmental cleaning Encourage use of sick leave for self-isolation at home

  30. More information Washington State Department of Health http://www.doh.wa.gov/H1N1/ Local public health departments http://www.doh.wa.gov/LHJMap/ Federal government http://www.flu.gov/

  31. Thank you. Questions?