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 [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 2.24.06.]

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

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 To 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.

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

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 Influenza 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.

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

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

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) 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.

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 It 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.

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

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 It 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.

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 In the United States each year, illness from influenza has a major impact on the people’s health and the nation’s economy.

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 It’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.

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 Now, 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.

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 Although 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.

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

Estimates of Impact of an Influenza Pandemic Moderate (1957-like) Severe (1918-like) Illness 90 million (30%) Outpatient medical care 45 million (50%) Hospitalization 865,000 9, 900,000 ICU care 128,750 1,485,000 Mechanical ventilation 64,875 745,500 Deaths 209,000 1,903,000

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 Avian 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.

Human Acquisition of H5N1

Avian Influenza A (H5N1): Why is Concern So High? Direct Impact on Humans 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 Avian 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.

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 2.24.06.]

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

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

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

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 Distance between chairs Percentage of carriers or cases <102 cm 27% (20/73)* >102 cm 7% (5/71)* *P=0.0001 for the difference

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

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.

Among students in residence halls AJIC 2003;31:364-70 Evidence for Benefits of Hand Hygiene Among students in residence halls AJIC 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

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.

Control of Pandemic Influenza in Communities

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

Would Exact a Horrible Toll Severe Pandemic (1918-like) A 1918 Pandemic Today Would Exact a Horrible Toll 50% or more of those who become ill will seek medical care Severe Pandemic (1918-like) Illness 90 million (30%) Outpatient medical care 45 million (50%) Hospitalization 9, 900,000 ICU care 1,485,000 Mechanical ventilation 745,500 Deaths 1,903,000

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 Slow Down Introduction in the United States Right now there are two primary goals for public health systems: To prevent or delay entry of a novel virus with pandemic potential by imposing 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 virus quarantining, on a short-term basis, other passengers who may have been exposed to such ill travelers Preparedness has to occur in locally. All communities should be involved.

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 2. To slow the spread of infection within the United States by quickly identifying cases and instituting pharmaceutical and non-pharmaceutical interventions, including Isolation procedures for the sick (stay home, school closures, other social measures) Proper utilization of medical resources Use of current antivirals for treatment, not prevention Vaccine production to prevent illness In 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 society Impact Prepared Weeks

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

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

Who Infects Whom? Likely sites of transmission Children/Teenagers 29% To Children To Teenagers To Adults To Seniors Total From From Children 21.4 3.0 17.4 1.6 43.4 From Teenagers 2.4 10.4 8.5 0.7 21.9 From Adults 4.6 3.1 22.4 1.8 31.8 From Seniors 0.2 0.1 0.8 1.7 2.8 Total To 28.6 16.6 49.0 5.7 Likely sites of transmission Children/Teenagers 29% Adults 59% Seniors 12% School Household Workplace Demographics Glass, RJ, et al. Local mitigation strategies for pandemic influenza. NISAC, SAND Number: 2005-7955J

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

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

Weekly mortality data provided by Marc Lipsitch (personal communication)

Liberty Loan Parade Sept 28, 1918

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

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

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 We 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.

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 [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 2.24.06.]