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

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Presentation on theme: "E & S Loss Control Executive Forum An Introduction to Seasonal, Avian and Pandemic Influenza Toby L Merlin, MD Director, Division of Partnerships and Strategic."— Presentation transcript:

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

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

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 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 H1 – H16 H1 – H3 Human Influenza A Viruses Human Influenza A Viruses

7 Emergence of Influenza A Viruses in Humans H1 H3 H2 H7* H5* H9* 1918 Flu H1N Flu H2N Flu H3N * 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) 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 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 - 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 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 >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 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 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 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 Emergence of Influenza A Viruses in Humans H1 H3 H2 H7* H5* H9* 1918 Flu H1N Flu H2N Flu H3N * Avian Flu

17 Moderate (1957-like)Severe (1918-like) Illness90 million (30%) Outpatient medical care45 million (50%) Hospitalization865,0009, 900,000 ICU care128,7501,485,000 Mechanical ventilation64,875745,500 Deaths209,0001,903,000 Estimates of Impact of an Influenza Pandemic

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

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 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

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

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

24 Influenza Transmission 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 Viruses:

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 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: Am J Med 1948;4:690 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: Am J Med 1948;4:690 Distance between chairsPercentage of carriers or cases <102 cm27% (20/73)* >102 cm7% (5/71)* *P= for the difference

27 Prevention of Contact Transmission Influenza viruses are enveloped. Effectively inactivated by: Detergents Alcohol products Bleach Household disinfectants 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. 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 Among students in residence halls AJIC 2003;31: 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 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 Evidence for Benefits of Hand Hygiene

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. 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 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 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 Without intervention, expect international spread in 1 month and U.S. cases in 1 to 2 months. Without intervention, expect international spread in 1 month and U.S. cases in 1 to 2 months. Containment May Be Possible

33 A 1918 Pandemic Today Would Exact a Horrible Toll A 1918 Pandemic Today Would Exact a Horrible Toll Severe Pandemic (1918-like) Illness90 million (30%) Outpatient medical care45 million (50%) Hospitalization9, 900,000 ICU care1,485,000 Mechanical ventilation745,500 Deaths1,903,000 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 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 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 Weeks Impact Prepared Unprepared

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

38 To ChildrenTo TeenagersTo AdultsTo SeniorsTotal From From Children From Teenagers From Adults From Seniors Total To Children/Teenagers 29% Adults 59% Seniors 12% Children/Teenagers 29% Adults 59% Seniors 12% Demographics Glass, RJ, et al. Local mitigation strategies for pandemic influenza. NISAC, SAND Number: J School Household Workplace Likely sites of transmission Who Infects Whom?

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 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 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 Estimated attack rate before interventions: 2.2%

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

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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 CDCs science and information Detail how to information for actions Continuity planning Infection control Risk communication Put information in one place for easy access Build on CDCs science and information

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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 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


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