E & S Loss Control Executive Forum An Introduction to Seasonal, Avian and

1. E & S Loss Control Executive Forum An Introduction to Seasonal, Avian and Pandemic Influenza Toby L Merlin, MD Director, Division of Partnerships and Strategic Alliances November 15, 2006

2. Introduction to Influenza • Seasonal, avian, and pandemic • Control measures for individuals, households, and workplaces • Control measures for communities

3. Definition of Influenza • A contagious disease caused by an RNA virus • Primarily affects the respiratory tract • Can cause severe illness and lead to life-threatening complications • A global infectious disease threat • An annual public health problem

4. Subtyped based on surface glycoproteins • 16 hemagglutinins (HA) and 9 neuraminidases (NA) • Current human subtypes: H1N1, H3N2 Segmented genome Influenza A Viruses HA NA

5. Influenza Viruses • Naturally infect several animal species • Birds • Mammals including people • People usually infected only by human viruses • Wild birds main reservoir for influenza A viruses • All known “A” subtypes circulate in wild birds • Infect wild and domesticated birds • Ultimate source for viruses (and virus genes) infecting other animal species

6. Avian Influenza A Viruses Human Influenza A Viruses H1 – H16 H1 – H3

7. 1918 1957 1968 Flu H1N1 Flu H3N2 Flu H2N2 Emergence of Influenza A Viruses in Humans H9* 1998 1999 2003 H5* 1997 2003-2006 H7* 1980 1996 2002 2003 2004 H1 H3 H2 H1 1977 1915 1925 1935 1945 1955 1965 1975 1985 1995 2005 2006 * Avian Flu

8. Antigenic Change:A Key Feature of Influenza Viruses • Change more than other respiratory viruses • Minor changes occur constantly (“drift”) • Cumulative • Reason why vaccine is updated each year • Radical change occurs infrequently (“shift”) • New surface protein (no immunity among people)

9. The “Flu” • Influenza is a viral illness that is easily confused with other infections, such as • Colds • Other viral infections • Influenza usually is self-limited to about a week of illness • Complications from influenza can contribute to serious secondary infections

10. Usual Influenza Symptoms - Fever - Headache - Fatigue - Dry cough - Body aches - Runny or stuffy nose • Children also may have gastrointestinal symptoms – nausea, vomiting, or diarrhea

11. How Influenza Viruses Spread • Primarily 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

12. Average Seasonal Impact of Influenza in the United States • >200,000 hospitalizations / year • about 36,000 deaths / year (>90% in elderly during regular seasons) • Substantial economic impact • Lost work / school days • Estimated $37.5 billion cost

13. Pandemic vs. Seasonal Influenza • Seasonal outbreaks • Caused by subtypes of influenza viruses that already circulate among people • Pandemic outbreaks • Caused by: • New subtypes • Subtypes that have never circulated among people, or • Subtypes that have not circulated among people for a long time

14. Three Criteria for a Pandemic • An influenza pandemic is a global outbreak of disease that occurs when • A new influenza A virus appears or “emerges” in the human population, and • It causes serious illness in humans, and • It spreads easily from person to person worldwide

15. Concerns about Pandemic Influenza • Rapid global spread (morbidity and mortality) • Shortages and delays – vaccines and antiviral medications • Increases burden on hospitals and outpatient care systems • Simultaneous impacts that disrupt national and community infrastructures

16. 1918 1957 1968 Flu H1N1 Flu H3N2 Flu H2N2 Emergence of Influenza A Viruses in Humans H9* 1998 1999 2003 H5* 1997 2003-2006 H7* 1980 1996 2002 2003 2004 H1 H3 H2 H1 1977 1915 1925 1935 1945 1955 1965 1975 1985 1995 2005 2006 * Avian Flu

17. Estimates of Impact of an Influenza Pandemic

18. Avian Influenza A (H5N1):Why is Concern So High? Impact on Animals and Economy • Lethal to poultry and other mammals • Present in healthy waterfowl - shed in feces • Has had (and could have greater) major economic impact

19. Human Acquisition of H5N1

20. Avian Influenza A (H5N1):Why is Concern So High? • Has caused severe disease in humans who have become infected • Limited human-to-human transmission in Southeast Asia • Could evolve to become readily transmissible in humans • No human H5N1 vaccine commercially available • Limited supply of expensive antiviral medicines of unknown value in managing pandemic Direct Impact on Humans

22. Control and Prevention of Influenza in Individuals, Households, and Workplaces

23. Tools for Control and Prevention of Influenza • Vaccines • Anti-virals • Transmission Interventions (Infection Control) • Contact Interventions (Social Distancing)

24. Influenza Transmission Viruses: Leave original host Survive in transit Delivered to a susceptible host Reach a susceptible part of the host Escape host defenses Multiply and cause tissue damage

25. Infection Control / Social Distancing Measures • Transmission Interventions (Infection Control) • Facemasks • Cough etiquette • Hand hygiene • Isolation of ill, quarantine of exposed • Contact Interventions (Social Distancing) • School closure • Cancellation of mass gatherings • Alternatives to face-to-face contact at work • Increasing distance, decreasing contacts

26. Evidence for Benefits of Physical Separation • Proximity of less than 3 feet has been associated with increased risk for transmission of infections via respiratory droplets. New Engl J Med 1982;307:1255-7 Am J Med 1948;4:690 *P=0.0001 for the difference

27. Prevention of Contact Transmission Influenza viruses are enveloped. Effectively inactivated by: • Detergents • Alcohol products • Bleach • Household disinfectants

28. Evidence for Benefits of Hand Hygiene • Hand hygiene reduces the respiratory infections in healthcare and community settings. Among Navy recruits Am J Prev Med 2001;21:79-83 • Handwashing program implemented at a Navy training center. • 45% reduction in outpatient visits for respiratory illness. • Frequent hand washers had fewer respiratory illnesses.

29. Evidence for Benefits of Hand Hygiene Among students in residence hallsAJIC 2003;31:364-70 • College dorms were randomized to having alcohol hand rubs in various locations vs. not. • Hand rub groups had: • 14.8%-39.9% reduction in respiratory illnesses • 43% fewer sick days

30. Protecting the Workplace Exclude sources of infection. • Screen and exclude individuals with fever or respiratory symptoms. • Exclude individuals with ill household members. Prevent transmission within the workplace. • Optimize hand hygiene. • Facilitate respiratory etiquette. • Maintain environmental hygiene.

31. Control of Pandemic Influenza in Communities

32. Containment May Be Possible Without intervention, expect international spread in 1 month and U.S. cases in 1 to 2 months. • Failed containment may still delay international spread by 1 month • Severe travel restrictions may delay U.S. cases by 1-4 weeks • Border screening difficult because persons may transmit infection for up to a day before they develop illness

33. A 1918 Pandemic Today Would Exact a Horrible Toll • 50% or more of those who become ill will seek medical care

34. HHS Pandemic Influenza Doctrine: Saving Lives • Prevent or at least delay introduction into the United States • May involve travel advisories, exit or entry screening • For first cases, may involve isolation / short-term quarantine of arriving passengers

35. HHS Pandemic Influenza Doctrine: Saving Lives • Slow spread, decrease illness and death, buy time • Antiviral treatment and isolation for people with illness • Quarantine for those exposed • Social distancing • Vaccine when available • Local decisions Unprepared Prepared Impact Weeks

36. Potential Tools in Our Toolbox • Our best countermeasure – vaccine – will probably be unavailable during the first wave of a pandemic • The supply of antiviral medications is limited • Infection control and social distancing measures

37. #1 Pandemic outbreak: No intervention #2 Daily Cases Pandemic outbreak: With intervention #3 Days since First Case The Wave 1. Delay disease transmission and outbreak peak 2. Decompress peak burden on infrastructure 3. Diminish overall cases and health impacts

38. School Household Workplace Who Infects Whom? Likely sites of transmission Children/Teenagers 29% Adults 59% Seniors 12% Demographics Glass, RJ, et al. Local mitigation strategies for pandemic influenza. NISAC, SAND Number: 2005-7955J

39. Example: How we might minimize impact of a severe pandemic • Closing schools • Keeping kids and teens at home • Social distancing at work and in the community • Isolating ill individuals and voluntary home quarantine of household contacts • Treating the ill and providing targeted antiviral prophylaxis to household contacts • Implementing measures in a uniform way as early as possible during community outbreaks

40. Longini: Social Distancing, Close Schools, Treat the Ill, Treat Close Friends and Families of the Ill

41. Weekly mortality data provided by Marc Lipsitch (personal communication)

42. Liberty Loan Parade Sept 28, 1918

43. St. Louis Estimated attack rate before interventions: 2.2% Mayor closes “theaters, moving picture shows, schools, pool and billiard halls, Sunday schools, cabarets, lodges, societies, public funerals, open air meetings, dance halls and conventions until further notice” Closing order withdrawn

44. Pandemic Influenza Checklists • Provide framework for action • Move from uncertainty to measured, informed action • Identify roles and responsibilities of multiple sectors

46. Pandemic Influenza Toolkits • Detail “how to” information for actions • Continuity planning • Infection control • Risk communication • Put information in one place for easy access • Build on CDC’s science and information

48. E & S Loss Control Executive Forum An Introduction to Seasonal, Avian and Pandemic Influenza Toby L Merlin, MD Director, Division of Partnerships and Strategic Alliances National Center for Health Marketing/CCHIS November 15, 2006