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Novel Influenza A (H1N1) United States, 2009

Novel Influenza A (H1N1) United States, 2009. ACHA 2009 Annual Meeting May 27 th , 2009, San Francisco Jane Seward, M.B.B.S., M.P.H Acting Deputy Director National Center for Immunization and Respiratory Diseases Centers for Disease Control and Prevention

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Novel Influenza A (H1N1) United States, 2009

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  1. Novel Influenza A (H1N1) United States, 2009 ACHA 2009 Annual Meeting May 27th, 2009, San Francisco Jane Seward, M.B.B.S., M.P.H Acting Deputy Director National Center for Immunization and Respiratory Diseases Centers for Disease Control and Prevention The findings and conclusions in this presentation are those of the authors and do not necessarily represent the views of the Centers for Disease Control and Prevention

  2. Outline • Influenza and influenza virus • Antigenic changes and pandemic viruses • Novel influenza A H1N1 • U.S. • Global • Guidance documents • Institutions of Higher Learning • Vaccine and next steps • Summary

  3. Influenza • Highly infectious viral illness • First pandemic in 1580 • At least 4 pandemics in 19th century • Estimated 21 million deaths worldwide in pandemic of 1918-1919 • Virus first isolated in 1933

  4. Seasonal Influenza, U.S. Annual Average Disease Burden • 15 – 60 million cases(5 – 20% of U.S. population) • 200,000 hospitalizations • 36,000 deaths Prevention of Influenza, Recommendations of ACIP MMWR 2008; 57 (RR-7)

  5. Influenza Virus • Single-stranded RNA virus • Orthomyxoviridae family • 3 types: • A: moderate/severe disease, humans – all ages, animals • B: milder disease, children, humans • C: rarely reported humans • Subtypes of type A determined by hemagglutinin and neuraminidase

  6. Type of nuclear material Neuraminidase Hemagglutinin A/Fujian/411/2002 (H3N2) Virus type Geographic origin Strain number Year of isolation Virus subtype Influenza Virus

  7. Influenza Antigenic Changes • Hemagglutinin and neuraminidase antigens change with time • Changes occur as a result of point mutations in the virus gene (antigenic drift), or due to exchange of a gene segment with another subtype of influenza virus (antigenic shift) • Impact of antigenic changes depend on extent of change (more change usually means larger impact) • Antigenic drift • in 2002-2003, A/Panama/2007/99 (H3N2) virus was dominant • A/Fujian/411/2002 (H3N2) appeared in late 2003 and caused widespread illness in 2003-2004

  8. Influenza Antigenic Changes • Antigenic Shift • major change, new subtype • caused by exchange of gene segments • may result in pandemic • Example of antigenic shift • H2N2 virus circulated in 1957-1967 • H3N2 virus appeared in 1968 and completely replaced H2N2 virus

  9. Severity of Pandemic Moderate Severe Severe Moderate Mild Influenza Type A Antigenic Shifts Subtype H3N2 H1N1 H2N2 H3N2 H1N1 Year 1889 1918 1957 1968 1977

  10. Possible Pathways for Generation of Pandemic Influenza Viruses Avian virus Avian reassortant virus Reassortment in humans Human virus Avian virus Avian-human pandemic reassortant virus Reassortment in swine

  11. Triple Reassortant Swine Influenza A (H1) Viruses in Humans, U.S., Dec 2005- Feb 2009 • 11 sporadic cases of infections in humans • Age range 16 months – 48 years (median 10 years) • Incubation period 3 – 9 days • Symptoms fever (90%), cough (100%), headache (60%) and diarrhea (30%) • All recovered • 9 cases had exposure to pigs • One suspected case of human to human transmission Shinde V et al., NEJM 2009:361

  12. Novel Influenza A Virus Infections • Novel influenza A virus infections are human infections with influenza A virus subtypes that are different from the currently circulating human subtypes (A/H1 and A/H3) Swine origin influenza virus (S-OIV) infection in humans is a novel influenza A virus infection

  13. April 17, 2009, 2 children in Counties in Southern California with febrile respiratory illnesses confirmed to be a swine influenza A H1N1 virus infections No contact with pigs No links between the 2 cases Source of infection unknown MMWR dispatch April 21st Novel Influenza, U.S., 2009

  14. April 24th, 6 additional cases reported from southern CA and TX including 2 cases in the same family Outbreaks of severe respiratory disease and deaths in Mexico reported due to the same influenza virus April 26th: Public health emergency declared DHHS Novel Influenza, U.S., 2009

  15. United States, March 28--May 4, 2009 Number of confirmed (N = 394)* and probable (N = 414) cases of novel influenza A (H1N1) virus infection with known dates of illness onset Mexico, March 11--May 3, 2009 Number of confirmed (N = 822) and Suspected (N = 11,356) cases of novel influenza A (H1N1) virus infection with known dates of illness onset MMWR May 8th, 2009

  16. MMWR May 8th, 2009

  17. http://content.nejm.org/cgi/content/full/NEJMoa0903810?query=TOChttp://content.nejm.org/cgi/content/full/NEJMoa0903810?query=TOC

  18. Comparison of H1N1 Swine genotypes Novel Influenza A H1N1 (quadruple reassortant) virus Triple reassortant swine virus Novel Influenza A H1N1 contains genes from: North American swine lineage Eurasian swine lineage Avian, North American lineage Seasonal H3N2 Swine Flu investigation team NEJM May 7, 2009

  19. Clinical Symptoms (N=354 Confirmed Cases) • Fever (94%) • Cough (92%) • Sore throat (66%) • Diarrhea (25%) • Vomiting (25%) Dawood FS et al., NEJM 2009:361 (May 7)

  20. Age Distribution of Confirmed Cases(N=532) • < 5 years 18% • 5-9 years 12% • 10-19 years 40% • 19-50 years 35% • ≥ 51 years 5% Dawood FS et al., NEJM 2009:361 (May 7)

  21. The Lancet: Volume 373, Issue 9674, Page 1495 (2 May 2009-8 May 2009)

  22. Surveillance Transition • State reporting • From line list to aggregate reporting • Total cases, deaths, hospitalizations • Population-based surveillance using existing surveillance systems • Laboratory • State confirmation testing of novel H1N1 • Guidance to PH lab clinicians has been distributed • CDC is focusing on validation of state lab testing and viral isolation and genetic testing

  23. U.S. Human Cases of H1N1 Flu Infection • As Of May 26, 2009 • 6,764 cases, 10 deaths in 48 states including DC • http://www.cdc.gov/h1n1flu/update.htm

  24. Percentage of Visits for ILI Reported by the U.S. Outpatient ILI Surveillance Network (ILINet)

  25. ILINet Data by Region

  26. Ongoing and Current Seasonal Influenza Surveillance – Mortality 122 U.S. Cities

  27. Pandemic Alert Status Inter-Pandemic Pandemic Alert Period Pandemic Period WHOPhase 1 2 3 4 5 6 Animal Outbreak Suspected Human Outbreak Overseas Confirmed Human Outbreak Overseas Widespread Outbreaks Overseas First Human Case in N.A. Spread Throughout United States Recovery USGStage 0 1 2 3 4 5 6 CDC Interval Investigation Recognition Initiation Accel Peak Decel Resolution

  28. Pandemic Severity Index? Mexico estimate 0.4% (0.3% - 1.5%) Fraser C et al, Science Express 11 May 2009 US: estimate of true # cases? Using reported cases and deaths, CFR = 0.15% If 1/10 cases confirmed/reported, CFR = 0.02%

  29. Epidemiology/Surveillance Novel Influenza A (H1N1) - 21 May 2009 1100 EDT U.S. WHO/NREVSS Collaborating Laboratories Summary, 2008-09 43%* 32%* * Percentage of all positive influenza specimens that are Novel Influenza A(H1N1) or Influenza A (unable to subtype) for the week indicated 73%*

  30. Anti-viral Resistance

  31. Recent Publications

  32. CDC Goals and Interim Guidance related to Novel Influenza A H1N1 • Goals: prevent transmission and reduce disease severity • Guidance documents: • Surveillance case definitions, laboratory testing • Schools, colleges, and universities • Pregnant and breastfeeding women • Travel industry • Emergency personnel • Clinician guidance for patients and specific audiences • Infection control guidance for healthcare facilities • Correctional and detention facilities

  33. Laboratory Testing • Real-time PCR assay to detect seasonal influenza A, B, H1, H3 and avian H5 serotypes is approved by FDA and distributed in December 2008 to U.S’s public health laboratories and WHO’s global influenza surveillance network • CDC has developed primers and probes specific for swine influenza (H1 and H3 subtypes) – protocol available at CDC website • Under Project BioShield act of 2004, FDA has issued an emergency use authorization, allowing the use of this assay by state public health laboratories

  34. Preventive Measures • Cover your nose and mouth with a tissue when you cough or sneeze • Throw the tissue in the trash after you use it • Wash your hands often with soap and water, especially after you cough or sneeze. Alcohol-based hand cleaners are also effective • Avoid close contact with sick people • Avoid touching your eyes, nose or mouth. Germs spread this way • If you get influenza-like illness symptoms, stay home from work or school except to seek medical care and limit contact with others to keep from infecting them

  35. How Influenza Viruses Are Thought To Be Spread • Probably through respiratory droplets: • Coughing • Sneezing • Touching respiratory droplets on self, another person, or an object, then touching mucus membranes (e.g., mouth, nose, eyes) without washing hands • Droplet nuclei (airborne transmission) may also occur

  36. Length of Contagiousness • Likely similar to seasonal influenza viruses but data are needed • One day before ill person develops symptoms to up to 7 days after they get sick • Children may shed virus for longer periods

  37. Guidance for Sick Persons • Warning Signs in Children: • Fast breathing or trouble breathing • Bluish skin color • Not drinking enough fluids • Not waking up or not interacting • Irritable, the child does not want to be held • Flu-like symptoms improve but then return • with fever and worse cough • Fever with a rash • Warning Signs in Adults: • Difficulty breathing or shortness of breath • Pain or pressure in the chest or abdomen • Sudden dizziness • Confusion • Severe or persistent vomiting If you are sick, you should stay home and avoid contact with other people as much as possible. If you get sick and experience any of these warning signs, seek emergency medical care.

  38. Interim CDC Guidance for Institutions of Higher Education (May 11, 2009) • CDC is not currently recommending that institutions cancel or dismiss classes or other large gatherings • If confirmed cases of novel influenza A (H1N1) virus infection or a large number of cases of influenza like illness (ILI) (i.e. fever with either cough or sore throat) occur among students, faculty, or staff or in the community, institutions officials should consult with state and local health officials regarding an appropriate response • Because the spread of novel influenza A (H1N1) within a health professions school may pose special concerns, school administrators are strongly encouraged to contact their state and local public health authorities if they suspect that cases of ILI are present on their campuses • Students, faculty or staff who live either on or off campus and who have ILI should self-isolate (i.e., stay away from others) in their dorm room or home for 7 days after the onset of illness or at least 24 hours after symptoms have resolved, whichever is longer • If possible, persons with ILI who wish to seek medical care should contact their health care provider or campus health services to report illness by telephone or other remote means before seeking care. Institutions should assure that all students, faculty and staff receive messages about what they should do if they become ill with ILI, including reporting ILI to health services

  39. Interim CDC Guidance for Institutions of Higher Education (May 11, 2009) • If persons with ILI must leave their home or dorm room (for example, to seek medical care or other necessities) they should cover their nose and mouth when coughing or sneezing. A surgical loose-fitting mask can be helpful for persons who have access to these, but a tissue or other covering is appropriate as well. (See Interim Guidance for H1N1 Flu (Swine Flu): Taking Care of a Sick Person in Your Home) • Roommates, household members, or those caring for an ill person should follow guidance developed for caring for sick persons at home. (See Interim Guidance for H1N1 Flu (Swine Flu): Taking Care of a Sick Person in Your Home) • Persons who are at high risk of complications from novel influenza A (H1N1) infection (for example, persons with certain chronic medical conditions, children less than 5 years, persons 65 years or older, and pregnant women) should consider their risk of exposure to novel influenza if they attend public gatherings in communities where novel influenza A virus is circulating. In communities with several reported cases of novel influenza A (H1N1) virus infection, persons who are at risk of complications from influenza should consider staying away from public gatherings

  40. Groups at Higher Risk for Severe Illness from Novel Influenza A (H1N1) Infection • Children younger than 5 years old • Persons aged 65 years or older • Children and adolescents (younger than 18 years) who are receiving long-term aspirin therapy and who might be at risk for experiencing Reye syndrome after influenza virus infection • Pregnant women • Adults and children who have pulmonary, including asthma, cardiovascular, hepatic, hematological, neurologic, neuromuscular, or metabolic disorders such as diabetes • Adults and children who have immunosuppression (including immunosuppression caused by medications or by HIV) • Residents of nursing homes and other chronic-care facilities

  41. Interim CDC Guidance for Institutions of Higher Education: Large Gatherings • Institutions should encourage persons with ILI to stay home and away from large gatherings • Persons who are sick should be instructed to: • limit their contact with other people as much as possible and to stay home for 7 days after their symptoms begin or until they have been symptom-free for 24 hours, whichever is longer • use appropriate respiratory and hand hygiene

  42. CDC Interim Guidance for Institutions of Higher Learning (cont.) Institutions should consider the following in preparation for possible outbreaks of novel influenza A (H1N1): • Establishing a relationship with their state and local health departments • Keeping informed regarding the evolving situation through regular visits to the CDC's H1N1 Flu web site • Developing educational messages in a variety of formats regarding the illness and how to reduce the spread of influenza. (See H1N1 Flu and You) • Alternative educational delivery such as distance learning, web-based learning, or other ways to increase social distancing • Planning for assistance for students with ILI, including provision for meals, medications, and other care • Developing contingency plans for how to reduce exposure of non-ill students, staff and faculty to ill students, staff and faculty

  43. Recommendations for Treatment with Anti-viral Medications • All hospitalized patients with confirmed, probable or suspected novel influenza (H1N1) • Patients who are at higher risk for seasonal influenza complications Note: SNS deployed antiviral medications to all states

  44. Close contacts of cases (confirmed, probable, or suspected) who are at high-risk for complications of influenza Health care personnel, public health workers, or first responders who have had a recognized, unprotected close contact exposure to a person with novel (H1N1) influenza virus infection (confirmed, probable, or suspected) during that person’s infectious period Recommendations for Post-exposure Antiviral Prophylaxis

  45. Recommendations for Outbreak Control

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