Presentation on theme: "E & S Loss Control Executive Forum"— Presentation transcript:
1 E & S Loss Control Executive Forum An Introduction toSeasonal, Avian andPandemic InfluenzaToby L Merlin, MDDirector, Division of Partnerships and Strategic AlliancesNovember 15, 2006[Presenters: Please note current slide date on title slide to be sure you are using the most up-to-date slide set. The slide set was developed by the Influenza Branch, Division of Viral and Rickettsial Diseases, National Center for Infectious Diseases, Centers for Disease Control and Prevention. This slide set is current as of ]
2 Introduction to Influenza Seasonal, avian, and pandemicControl measures for individuals, households, and workplacesControl measures for communities
3 Definition of Influenza A contagious disease caused by an RNA virusPrimarily affects the respiratory tractCan cause severe illness and lead to life-threatening complicationsA global infectious disease threatAn annual public health problemTo begin, it’s important to be clear about the definition and symptoms of influenza. Influenza is a contagious disease caused by an RNA virus. It poses both a global infectious disease threat and an annual public health problem. Influenza primarily infects the respiratory tract (nose, throat, and lungs). The disease can cause severe illness and lead to life-threatening complications, such as pneumonia, in many people.
4 Influenza A Viruses Subtyped based on surface glycoproteins 16 hemagglutinins (HA) and 9 neuraminidases (NA)Current human subtypes: H1N1, H3N2Segmented genomeHAInfluenza A viruses contain surface proteins called hemagglutinins (or HA) and neuraminidases (or NA). Scientists have identified subtypes of influenza viruses based on the genetic arrangement of these HA and NA proteins, as well as other factors. Although the 16 HA and 9 NA proteins may combine in many ways, only 2 subtypes currently spread among humans: H1N1 and H3N2. Technically, other subtypes can infect humans, but they don’t spread from person to person regularly.NA
5 Influenza Viruses Naturally infect several animal species BirdsMammals including peoplePeople usually infected only by human virusesWild birds main reservoir for influenza A virusesAll known “A” subtypes circulate in wild birdsInfect wild and domesticated birdsUltimate source for viruses (and virus genes) infecting other animal speciesInfluenza viruses infect a number of animal species, including birds and mammals. People usually are infected only by specific human influenza viruses that circulate globally throughout the year. People can be infected by influenza A and influenza B viruses. A combination of influenza A and B viruses therefore is included in the annual influenza vaccine people can receive. Influenza A viruses, of particular interest in this presentation, circulate in wild birds and infect both wild and domesticated birds. Wild birds are a primary source for influenza A viruses that infect other species.
6 Avian Influenza A Viruses Human InfluenzaA VirusesH1 – H16H1 – H3Some types of influenza A viruses infect and spread among birds and are called avian viruses. These have demonstrated a capacity to recombine or to change in other ways that enhance their capacity to infect species other than birds, including humans. This will be important to remember we are considering viruses that gain the potential for evolving into a pandemic.
7 Emergence of Influenza A Viruses in Humans 2003H5*H7*H1H3H2H1Many avian influenza viruses that circulate globally could evolve into a strain that could cause a pandemic. There were 3 influenza pandemics during the past century, each with its own characteristics and impacts. Scientists expect influenza pandemics to continue periodically. They can begin anywhere in the world.19771918Flu H1N11957Flu H2N21968Flu H3N2* Avian Flu
8 Antigenic Change: A Key Feature of Influenza Viruses Change more than other respiratory virusesMinor changes occur constantly (“drift”)CumulativeReason why vaccine is updated each yearRadical change occurs infrequently (“shift”)New surface protein (no immunity among people)It’s important to understand that influenza viruses change often. Minor changes, also called “antigenic drift,” occur constantly. That’s why it’s important to be vaccinated annually; scientists try to match the components of each year’s vaccine with predicted circulating strains by using knowledge gained through domestic and global surveillance networks. Sometimes, more radical genetic changes, also called “antigenic shift,” occur, which can result in the emergence of a novel influenza virus in the human population.
9 The “Flu”Influenza is a viral illness that is easily confused with other infections, such asColdsOther viral infectionsInfluenza usually is self-limited to about a week of illnessComplications from influenza can contribute to serious secondary infectionsIt is easy to mistake influenza for other infections, such as colds and other viral infections. Although seasonal influenza usually lasts only about a week for many people, it can last longer and can contribute to serious secondary infections, such as pneumonia. People sometimes confuse influenza with “stomach flu” because of the use of “flu” in both terms. “Stomach flu” actually is a general term for gastroenteritis, which results in vomiting and diarrhea – symptoms not usually seen in typical cases of seasonal influenza.
10 Usual Influenza Symptoms - Fever - Headache- Fatigue - Dry cough- Body aches - Runny or stuffy noseChildren also may have gastrointestinal symptoms – nausea, vomiting, or diarrheaUsual symptoms of seasonal influenza include fever, headache, fatigue, dry cough, body aches, and a runny or stuffy nose. Children also may have gastrointestinal symptoms, such as nausea, vomiting, or diarrhea.
11 How Influenza Viruses Spread Primarily through respiratory dropletsCoughingSneezingTouching respiratory droplets on self, another person, or an object, then touching mucus membranes (e.g., mouth, nose, eyes) without washing handsIt is thought that the main way influenza viruses are spread from person to person is through transmission of respiratory droplets during coughing and sneezing. Close contact (about 3 feet or less) usually is necessary for this type of spread. Influenza viruses also can spread by touching respiratory droplets on yourself, others, or an object, then touching mucus membranes, such as the mouth, nose, or eyes, without washing contaminated hands.
12 Average Seasonal Impact of Influenza in the United States >200,000 hospitalizations / yearabout 36,000 deaths / year(>90% in elderly during regular seasons)Substantial economic impactLost work / school daysEstimated $37.5 billion costIn the United States each year, illness from influenza has a major impact on the people’s health and the nation’s economy.
13 Pandemic vs. Seasonal Influenza Seasonal outbreaksCaused by subtypes of influenza viruses that already circulate among peoplePandemic outbreaksCaused by:New subtypesSubtypes that have never circulated among people, orSubtypes that have not circulated among people for a long timeIt’s important to understand the differences between seasonal and pandemic influenza. Seasonal influenza outbreaks are caused by influenza virus subtypes that already circulate among people. In contrast, pandemic outbreaks are caused by new subtypes, by subtypes that have never circulated among people, or by 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 whenA new influenza A virus appears or “emerges” in the human population, andIt causes serious illness in humans, andIt spreads easily from person to person worldwideNow, let’s turn to pandemic influenza, which is markedly different from influenza that circulates each year. Three factors are necessary for an influenza pandemic to occur: 1) a new influenza A virus must emerge in the human population; 2) the virus must cause serious illness in humans; and 3) the virus must spread easily from person to person.
15 Concerns about Pandemic Influenza Rapid global spread (morbidity and mortality)Shortages and delays – vaccines and antiviral medicationsIncreases burden on hospitals and outpatient care systemsSimultaneous impacts that disrupt national and community infrastructuresAlthough seasonal influenza is a serious disease that causes many illnesses and deaths each year, an influenza pandemic can have both immediate and long-term consequences to people in the United States and around the world.
16 Emergence of Influenza A Viruses in Humans 2003H5*H7*H1H3H2H1Many avian influenza viruses that circulate globally could evolve into a strain that could cause a pandemic. There were 3 influenza pandemics during the past century, each with its own characteristics and impacts. Scientists expect influenza pandemics to continue periodically. They can begin anywhere in the world.19771918Flu H1N11957Flu H2N21968Flu H3N2* Avian Flu
17 Estimates of Impact of an Influenza Pandemic Moderate (1957-like)Severe (1918-like)Illness90 million (30%)Outpatient medical care45 million (50%)Hospitalization865,0009, 900,000ICU care128,7501,485,000Mechanical ventilation64,875745,500Deaths209,0001,903,000
18 Avian Influenza A (H5N1): Why is Concern So High? Impact on Animals and EconomyLethal to poultry and other mammalsPresent in healthy waterfowl - shed in fecesHas had (and could have greater) major economic impactAvian influenza A (H5N1) strains currently circulating in many countries and Asia and spreading into Europe have a number of factors that are causing growing concern among scientists. Influenza H5N1 is having a major impact on animals and on the economies of affected countries.
20 Avian Influenza A (H5N1): Why is Concern So High? Direct Impact on HumansHas caused severe disease in humans who have become infectedLimited human-to-human transmission in Southeast AsiaCould evolve to become readily transmissible in humansNo human H5N1 vaccine commercially availableLimited supply of expensive antiviral medicines of unknown value in managing pandemicAvian influenza A (H5N1) strains also have caused severe disease in some humans, primarily through close or direct contact with poultry or other domesticated. The potential for the strains to mutate (reassort) through combination with other human influenza strains is a great concern, because such a change could produce a virus that would be both highly pathogenic and easily transmissible among humans.
22 Control and Prevention of Influenza in Individuals, Households, and Workplaces [Presenters: Please note current slide date on title slide to be sure you are using the most up-to-date slide set. The slide set was developed by the Influenza Branch, Division of Viral and Rickettsial Diseases, National Center for Infectious Diseases, Centers for Disease Control and Prevention. This slide set is current as of ]
23 Tools for Control and Prevention of Influenza VaccinesAnti-viralsTransmission Interventions (Infection Control)Contact Interventions (Social Distancing)
24 Influenza Transmission Viruses:Leave original hostSurvive in transitDelivered to a susceptible hostReach a susceptible part of the hostEscape host defensesMultiply and cause tissue damage
25 Infection Control / Social Distancing Measures Transmission Interventions (Infection Control)FacemasksCough etiquetteHand hygieneIsolation of ill, quarantine of exposedContact Interventions (Social Distancing)School closureCancellation of mass gatheringsAlternatives to face-to-face contact at workIncreasing 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;307:1255-7Am J Med 1948;4:690Distance 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:DetergentsAlcohol productsBleachHousehold disinfectants
28 Evidence for Benefits of Hand Hygiene Hand hygiene reduces the respiratory infections in healthcare and community settings.Among Navy recruitsAm J Prev Med 2001;21:79-83Handwashing 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;31:364-70 Evidence for Benefits of Hand HygieneAmong students in residence halls AJIC 2003;31:364-70College dorms were randomized to having alcohol hand rubs in various locations vs. not.Hand rub groups had:14.8%-39.9% reduction in respiratory illnesses43% 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.
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 monthSevere travel restrictions may delay U.S. cases by 1-4 weeksBorder screening difficult because persons may transmit infection for up to a day before they develop illness
33 Would Exact a Horrible Toll Severe Pandemic (1918-like) A 1918 Pandemic TodayWould Exact a Horrible Toll50% or more of those who become ill will seek medical careSevere Pandemic (1918-like)Illness90 million (30%)Outpatient medical care45 million (50%)Hospitalization9, 900,000ICU care1,485,000Mechanical ventilation745,500Deaths1,903,000
34 HHS Pandemic Influenza Doctrine: Saving Lives Prevent or at least delay introduction into the United StatesMay involve travel advisories, exit or entry screeningFor first cases, may involve isolation / short-term quarantine of arriving passengersPrevent or Slow Down Introduction in the United StatesRight now there are two primary goals for public health systems:To prevent or delay entry of a novel virus with pandemic potential byimposing travel advisories and possibly some travel restrictions;establishing medical screening at points of departure from foreign ports and points of arrival in the United States;isolating ill passengers who appear to be infected with the novel virusquarantining, on a short-term basis, other passengers who may have been exposed to such ill travelersPreparedness has to occur in locally. All communities should be involved.
35 HHS Pandemic Influenza Doctrine: Saving Lives Slow spread, decrease illness and death, buy timeAntiviral treatment and isolation for people with illnessQuarantine for those exposedSocial distancingVaccine when availableLocal decisionsUnprepared2. To slow the spread of infection within the United States by quickly identifying cases and instituting pharmaceutical and non-pharmaceutical interventions, includingIsolation procedures for the sick (stay home, school closures, other social measures)Proper utilization of medical resourcesUse of current antivirals for treatment, not preventionVaccine production to prevent illnessIn addition to these two public health system goals, the Federal Government has identified a third goal to: sustain infrastructure and mitigate impact to the economy and the functioning of societyImpactPreparedWeeks
36 Potential Tools in Our Toolbox Our best countermeasure – vaccine – will probably be unavailable during the first wave of a pandemicThe supply of antiviral medications is limitedInfection control and social distancing measures
37 The Wave 1. Delay disease transmission and outbreak peak 2. Decompress peak burden on infrastructure3. Diminish overall cases and health impactsDailyCases#1#2#3Days since First CasePandemic outbreak:No interventionWith intervention
38 Who Infects Whom? Likely sites of transmission Children/Teenagers 29% To ChildrenTo TeenagersTo AdultsTo SeniorsTotal FromFrom Children21.43.017.41.643.4From Teenagers2.410.48.50.721.9From Adults126.96.36.199.831.8From Seniors0.20.10.81.72.8Total To28.616.649.05.7Likely sites of transmissionChildren/Teenagers %Adults %Seniors %SchoolHouseholdWorkplaceDemographicsGlass, RJ, et al. Local mitigation strategies for pandemic influenza. NISAC, SAND Number: J
39 Example: How we might minimize impact of a severe pandemic Closing schoolsKeeping kids and teens at homeSocial distancing at work and in the communityIsolating ill individuals and voluntary home quarantine of household contactsTreating the ill and providing targeted antiviral prophylaxis to household contactsImplementing 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)
43 St. Louis 2.2% Estimated attack rate before interventions: 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 actionMove from uncertainty to measured, informed actionIdentify roles and responsibilities of multiple sectors
46 Pandemic Influenza Toolkits Detail “how to” information for actionsContinuity planningInfection controlRisk communicationPut information in one place for easy accessBuild on CDC’s science and informationWe continue to talk with people from business, education, healthcare, faith- and community-based organizations to refine our understanding of their particular assets and challenges.The Tool Kit will be Web-based so that we can update information and resources as we continually learn more about pandemic influenza. In addition, this format enables us to provide interactive support such as Webinars, on-line chats, and a venue for users to submit best practices and lessons learned.
48 E & S Loss Control Executive Forum An Introduction toSeasonal, Avian andPandemic InfluenzaToby L Merlin, MDDirector, Division of Partnerships and Strategic AlliancesNational Center for Health Marketing/CCHISNovember 15, 2006[Presenters: Please note current slide date on title slide to be sure you are using the most up-to-date slide set. The slide set was developed by the Influenza Branch, Division of Viral and Rickettsial Diseases, National Center for Infectious Diseases, Centers for Disease Control and Prevention. This slide set is current as of ]