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Stephen Sears, MD, MPH, CPE

Pandemic Influenza Novel Influenza A (H1N1). Stephen Sears, MD, MPH, CPE. Influenza. Seasonal influenza Pandemic influenza Novel influenza A (H1N1). Influenza Viruses. Types A Hemagglutinin (H1-H16 subtypes) Neuraminidase (N1-N9 subtypes) B C. Novel H1N1 Influenza.

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Stephen Sears, MD, MPH, CPE

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  1. Pandemic Influenza Novel Influenza A (H1N1) Stephen Sears, MD, MPH, CPE

  2. Influenza • Seasonal influenza • Pandemic influenza • Novel influenza A (H1N1)

  3. Influenza Viruses • Types • A • Hemagglutinin (H1-H16 subtypes) • Neuraminidase (N1-N9 subtypes) • B • C

  4. Novel H1N1 Influenza • First cases of human infection with novel H1N1 influenza virus were detected in April 2009 in California and Texas • Virus has spread rapidly and is now widespread internationally

  5. Novel H1N1 Influenza • Each year in US, seasonal influenza results in 36,000 deaths and >200,000 hospitalizations • H1N1 potentially is as serious as seasonal flu, if not more so, given there currently is no vaccine against this virus • Most people will not have immunity to H1N1, and illness may be more severe and widespread as a result

  6. The Two Mechanisms Whereby Pandemic Influenza Originates Belshe R. N Engl J Med 2005;353:2209-2211

  7. Characteristics of Pandemics • Novel virus • Severe illness in humans • Efficiently transmitted

  8. Recent Pandemics • 1918 (H1N1) • 500,000 deaths in U.S. • 1957 (H2N2) • 70,000 deaths in U.S. • 1968 (H3N2) • 34,000 deaths in U.S. • 2009 (H1N1) • ? deaths in U.S.

  9. World Health OrganizationPandemic Influenza Phases Phases 5- 6 / Pandemic Phase 4 Post Peak Phases 1-3 Post Pandemic Time Predominantly Animal Infections; Few Human Infections Sustained Human-to-Human Transmission Widespread Human Infection Possibility of Recurrent Events Disease Activity at Seasonal Levels

  10. Pandemic Assumptions • Attack rate of 25%-35% • Duration of a year or more in >2 waves • Each wave lasting 6-8 weeks in community • Healthcare system will be severely taxed if not overwhelmed

  11. Influenza Disease Spread Aerosolized droplets from coughing or sneezing upto a 6 foot radius Hand to face contact (nose, eyes, or mouth) after touching infected areas Virus infectious only up to 2-8 hrs on surfaces Incubation period 1 to 7 days (avg H1N1 3-4 days) Symptom duration 3 to 7 days but up to 14 days (avg H1N1 3-5 days) Contagious 1 day before symptoms to 10 days after symptoms peak period while febrile

  12. How does H1N1 Influenza spread? • Same as seasonal flu • Respiratory droplets • Coughing • Sneezing • Touching droplets on yourself, another person, or object then touching mouth, nose, or eye

  13. Influenza Like Illness (ILI) Symptoms to meet criteria for ILI: Fever plus sore throat or cough Other common symptoms Headache Muscle & joint aches Nausea, vomiting, or diarrhea Fatigue Pneumonia Shortness of breath

  14. Clinical Characteristics of H1N1US CDC Data

  15. H1N1 Age Distribution *Excludes 6,741 cases with missing ages Rate/100,000 by Single Year Age Groups: Denominator Source: 2008 Census Estimates, U.S. Census Bureau

  16. Hospitalization Rates *Hospitalizations with unknown ages are not included (n = 273) Rate/100,000 by Single Year Age Groups: Denominator Source: 2008 Census Estimates, U.S. Census Bureau

  17. Death Rates H1N1 U.S. Deaths, By Age Group

  18. H1N1 Flu vs Seasonal Flu H1N1 Flu Median age for cases = 12 yo Hospitalizations = 20 yo Deaths = 37 yo Seasonal Flu 2/3 of hospitalizations >65 yo >90% of deaths in those >65 yo

  19. Main Underlying Conditions for H1N1 Hospitalizations & Death Pregnancy Respiratory (Asthma, COPD, etc) Cardiovascular disease Diabetes Compromised immune system Neuromuscular disorders

  20. Emergency Warning Signs in Adults • Difficulty breathing • Pain or pressure in chest or abdomen • Sudden dizziness • Confusion • Severe or persistent vomiting • Flu-like symptoms improve but then return with fever and worse cough

  21. Emergency Warning Signs in Children • Fast breathing or trouble breathing • Bluish or gray skin color • Not drinking enough fluids • Severe or persistent vomiting • Not waking up or not interacting • Irritable; child does not want to be held • Flu-like symptoms improve, but then return with fever and worse cough

  22. H1N1 101 Surveillance MITIGATION Prevention Early Detection Isolation Treatment Vaccination Communication

  23. Goal of Mitigation

  24. H1N1 101 Mitigation PREVENTION How long can influenza virus remain viable on objects (such as books and doorknobs)? What kills influenza virus? What surfaces are most likely to be sources of contamination? What are some prevention steps we can use at work, home, and at school?

  25. Tissue, Please If you cough Or if you sneeze Cover your mouth With a tissue, please If no tissue Is in site Use your sleeve It is polite! http://www.coughsafe.com/ Maine’s own Dr. Ben Lounsbury

  26. H1N1 101 Mitigation EARLY DETECTION What are some early detection strategies we can implement in our community? Active - testing or prompting Passive – reminders Context

  27. H1N1 101 Mitigation ISOLATION Isolation vs Quarantine What are the new CDC recommendations for isolation? 24 hours symptom free 7 days in high-risk settings (hospitals, infant day care)

  28. Should I consider wearing a mask? If I have ILI and must go near others (breast feeding, doctor’s office visits, etc.) If I am high-risk and must be in a crowded setting or caring for someone with ILI

  29. School Mitigation If H1N1 severity is same as Spring, 2009: Stay home when sick Quickly separate ill staff and students Emphasize respiratory hygiene Routine cleaning Early treatment of high-risk who are ill Consider selective school dismissal

  30. Influenza Control • Vaccine • Antiviral drugs • Community containment

  31. 2009-10 Seasonal Influenza Vaccine • A (H1N1) • A (H3N2) • B

  32. Pandemic Vaccine • Single antigen • Novel influenza A (H1N1) • Vaccine will not be available till October • Vaccine supply may be limited initially

  33. Influenza Vaccine 2009-2010 Seasonal flu vaccine Expected in August/September Will begin prior to H1N1 vaccination program Usual recommendations for who should get it H1N1 flu vaccine Initial supply expected in fall Clinical trials currently underway Likely two shots, 3-4 weeks apart Given to priority groups first

  34. H1N1 Vaccine Current Tier I CDC Priority Groups Pregnant women Caregivers & household contacts for infants under 6 months of age Children 6 months to 25 yrs of age Health care workers including EMS Adults 25 to 65 with chronic medical conditions at risk for influenza complications

  35. H1N1 Vaccine PRIORITY GROUPS FOR H1N1 VACCINE 8,500 1% Pregnant women 18,500     3% caregivers of infants <6 months old 390,000    64% 6 months – 24 years of age 155,000    25% 25 – 65 year olds w/chronic conditions 37,000     6% Health care workers 6,000     1% EMS 615,000     TOTAL

  36. H1N1 Vaccine Will it have thimerosal? (preservative) There will be some t-free for young children and pregnant women What about the clinical trials? Determining doseage Will it have an adjuvant? Likely not Will the vaccine be administered under EUA? Unlikely

  37. What about the 1976 swine flu and vaccine safety concerns? • Winter: ~230 infected in Fort Dix, NJ, Jan/Feb • No spread • Fall: 40 million vaccinated • GBS associated with infections, include ILI • GBS 1/100,000 • 1976 vaccine excess of GBS = 1/100,000 • GBS decrease since 1990 • Enhanced monitoring planned • Must weigh risks and benefits

  38. US Federal government 2008. Available at: http://www.pandemicflu.gov/

  39. Antivirals • Neuraminidase inhibitors • Oseltamivir (Tamiflu) • Zanamivir (Relenza) • Adamantanes • Amantadine • Rimantadine

  40. Priority Groups for Antivirals • Treatment • Hospitalized patients • Those at high risk of severe disease • Prophylaxis • Close contacts who are • At high risk of severe disease • Health care workers who did not wear appropriate personal protective equipment

  41. Challenges to Antiviral Use • Differences in resistance between seasonal and pandemic viruses • Need to begin treatment within 48 hours of illness onset • Limited supply/inappropriate use

  42. The Future? (changes likely) • Presently it is expected that the current pandemic will affect 30% population over six month period with ~1% mortality rate • Most cases will be mild: • People will be sick at home for a week • High risk groups more likely to be hospitalized or die • Vaccines available for • Seasonal influenza (now) • H1N1 (later in fall) The Unknown????

  43. Major Strategies Prevent people from becoming ill Vaccination Hand washing Prevent spread between people Hand washing Cover nose/mouth with arm/tissue: not with your hand Stay home when you are ill until fever-free for 24 hrs Treat people who are ill Mild disease: stay home, rest, fluids, acetaminophen Call physician if ill or have chronic medical condition No aspirin for <18 yr olds

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