1/31/2013 DISEASE BASICS. Influenza; Implications for Public Health Professionals. Influenza: An Age-Old Disease, A Disease for All Ages

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1 Influenza; Implications for Public Health Professionals Phillip L. Barkley, M.D. Director of Student Health University of Florida DISEASE BASICS Influenza: An Age-Old Disease, A Disease for All Ages Epidemics described since 12th century Many animal species vulnerable Virus can move from animals to humans Aquatic birds: a reservoir for human disease Belshe RB. N Engl J Med. 2005;353:

2 History: Isolation, Transmissibility, Vaccination 1933: Influenza A virus isolated : Virus transmissibility confirmed : First vaccination research : Influenza B virus isolated 4 Types A & B cause epidemic human disease 5 1. Smith et al. Lancet.1933;2: Francis T Jr. Science : Francis T, Magill TP. J Exp Med. 1937;65: Francis T Jr. Science.1940;92: MMWR. Early Release.2006;55:1-3. Influenza Virus Type of nuclear material Hemagglutinin Neuraminidase A/Fujian/411/2002 (H3N2) Virus type Geographic origin Strain number Year of isolation Virus subtype 2

3 Biology of Influenza Influenza A A (H1N1) (first circulated globally in 1918) A (H3N2) (first circulated globally in 1968) A (H1N1) (AKA Swine Flu circulating since April 09) Influenza B Two lineages currently circulating Influenza C No subtypes Does not cause epidemics Causes common cold-like illnesses CDC. Available at: How the Virus Changes Antigenic drift: Minor genetic variations Occur yearly Associated with annual epidemics Permits virus to escape population s immunity 1 Antigenic shift: Major genetic variations Infrequent (decades apart), can spread quickly Produce novel viruses Causes global (pandemic) disease No human immunity 2 1. Cheung M, Lieberman JM. Contemp Pediatr. 2002;19: CDC. Available at: Acessed July 6, Epidemic, Pandemic, Interpandemic Epidemic Regional outbreak Excess disease incidence of varying magnitude Seasonal in temperate zones: Midwinter peak Pandemic Worldwide outbreak Severe disease Infrequent Interpandemic Refers to annual seasonal outbreaks Dolin R. N Engl J Med. 2005;353:

4 Influenza Pandemics in the 20 th Century 1918 Spanish influenza (H1N1) 1957 Asian influenza (H2N2) 1968 Hong Kong influenza (H3N2) ~ 500,000 US deaths; 1,2 40 million worldwide > 2 million worldwide 3 ~ 34,000 US deaths 3 historical UF impacts to pandemic 1918 Spanish flu Floyd Hall transformed into hospital Large percentage of the student body ill President Albert Murphree ill and confined to bed 1957 Asiatic Flu 2,092 Infirmary hospitalizations & Florida Gym used as overflow ~5,000 cases among ~11,000 student body UCLA football game cancelled due to high rates of flu Clinical Description/Diagnosis Incubation period 1 1 to 4 days Adults: infectious from day before to +5 days after illness onset Children: infectious 10 days (can shed virus several days before onset) Severely immunocompromised: Can shed virus for months Likely transmission paths 2 Coughing & sneezing respiratory droplets Contact with an infected person, not washing hands afterward 1. CDC. MMWR. Early Release.2006;55: American Academy of Pediatrics. Red Book. 2003,

5 Signs and Symptoms Abrupt onset: Fever, myalgia, headache, malaise, nonproductive cough, sore throat, rhinitis Differential diagnosis: Can be difficult based on symptoms alone, unless influenza is already present in the community Children and elderly can have different presentations Can last up through 7 days CDC. MMWR. Early Release.2006;55:2-3. Complications of Influenza Most vulnerable patients 1 Age 65 yrs and children 2 yrs of age Underlying chronic conditions at any age Heart or lung disease Diabetes Compromised immune system Secondary complications 2,3 Primary influenza viral pneumonia or secondary bacterial pneumonia Exacerbation of underlying cardiac or pulmonary disease Secondary or co-infection with other viral and bacterial pathogens 1. CDC. MMWR. Early Release.2006;55:3, HHS. Available at: Accessed July 6, American Academy of Pediatrics. Red Book., 2003;

6 Influenza Antiviral Agents* Amantadine and rimantadine Not recommended because of documented resistance in U.S. influenza isolates Zanamivir and oseltamivir neuraminidase inhibitors effective against influenza A and B should be used if an influenza antiviral drug is indicated for chemoprophylaxis or treatment *see influenza ACIP statement or CDC influenza website for details Severity of Disease in Children Common complications Acute otitis media (30% of cases) Bronchiolitis, bacterial rhinosinusitis Severe pneumococcal pneumonia Nonrespiratory complications Myositis, myocarditis Central nervous system Encephalitis Febrile seizures Reye syndrome Hospitalization rates at 2 yrs of age similar to rates in elderly Principi N, et al. Lancet Infect Dis. 2004; 4: Severity in Children, continued Deaths in US children, all ages Average 92 annually in children < 5 yrs In a cohort of 153 influenza-associated deaths in children ( ): Median age at death: 3 yrs 47% were previously healthy 33% had ACIP-defined high-risk condition Only 26% of ACIP-defined high-risk children had received 1 dose of influenza vaccine Bhat N, et al. N Engl J Med. 2005;353:

7 Groups Most Affected by Influenza Adults: Older at greatest risk for death 1 age 65: 90% of influenza-related deaths age 85: 32x more likely to die of influenza-related pneumonia than persons aged years Children: Youngest at greater risk for hospitalization 2 Under age 2 yrs Older children bear greater disease burden 3 School attendance increases disease transmission Ill family members transmit disease 1. Thompson WW, et al. JAMA. 2003;289: Bhat N, et al. N Engl J Med. 2005;353: Principi N, et al. Arch Dis Child. 2004;89: US Hospitalizations and Deaths : ~ 226,000 influenza-related hospitalizations/yr 1, : ~ 325,000 influenza-related US deaths 1,2 Current estimate: 36,000 deaths/yr 2,3 1. Dolin R. N Engl J Med. 2005;353: Thompson WW, et al. JAMA. 2003;289: CDC. MMWR (RR-05);1-11. CURRENT EPIDEMIOLOGY 7

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9 Florida ILINet Essence-Florida SHCC Cases 9

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11 VACCINATION 11

12 Vaccine Components A/California/7/2009 (H1N1)pdm09-like virus; A/Victoria/361/2011 (H3N2)-like virus; B/Wisconsin/1/2010-like virus (from the B/Yamagata lineage of viruses). Antigenic Characterization CDC has antigenically characterized 612 influenza viruses [Forty-one 2009 H1N1 viruses, 394 influenza A (H3N2) viruses, and 177 influenza B viruses] collected by U.S. laboratories since October 1, H1N1 [41]: All forty-one 2009 H1N1 viruses tested were characterized as A/California/7/2009-like, the influenza A (H1N1) component of the influenza vaccine for the Northern Hemisphere. Influenza A (H3N2) [394]: 392(99.5%) of the 394 H3N2 influenza viruses tested have been characterized as A/Victoria/361/2011-like, the influenza A (H3N2) component of the Northern Hemisphere influenza vaccine. 2 (0.5%) of the 394 H3N2 viruses tested showed reduced titers with antiserum produced against A/Victoria/361/2011. Influenza B (B/Yamagata/16/88 and B/Victoria/02/87 lineages) [177]: Yamagata Lineage [118]: 118 (66.7%) of the 177 influenza B viruses tested so far this season have been characterized as B/Wisconsin/1/2010-like, the influenza B component of the Northern Hemisphere influenza vaccine. Victoria Lineage [59]: 59 (33.3%) of 177 influenza B viruses tested have been from the B/Victoria lineage of viruses. Influenza Vaccine Doses million doses US million doses US (est) SHCC ,000 doses 12

13 Summary of influenza vaccination recommendations, 2011 All persons aged 6 months should be vaccinated annually. Protection of persons at higher risk for influenza-related complications should continue to be a focus of vaccination efforts as providers and programs transition to routine vaccination of all persons aged 6 months. When vaccine supply is limited, vaccination efforts should focus on delivering vaccination to persons who: --are aged 6 months--4 years (59 months); --are aged 50 years; --have chronic pulmonary (including asthma), cardiovascular (except hypertension), renal, hepatic, neurologic, hematologic, or metabolic disorders (including diabetes mellitus); --are immunosuppressed (including immunosuppression caused by medications or by human immunodeficiency virus); -- are or will be pregnant during the influenza season; --are aged 6 months--18 years and receiving long-term aspirin therapy and who therefore might be at risk for experiencing Reye syndrome after influenza virus infection; -- are residents of nursing homes and other chronic-care facilities; -- are American Indians/Alaska Natives; -- are morbidly obese (body-mass index 40); -- are health-care personnel; --are household contacts and caregivers of children aged <5 years and adults aged 50 years, with particular emphasis on vaccinating contacts of children aged <6 months; and --are household contacts and caregivers of persons with medical conditions that put them at higher risk for severe complications from influenza 13

14 Influenza Vaccinations Peak in Mid-November Vaccination Visits 4,000,000 3,500,000 3,000,000 2,500,000 2,000,000 Traditional Immunization Season Influenza vaccination visits a (three-year average) 1,500,000 1,000, ,000 0 Sep Oct Nov Dec Jan Feb Mar Reference: a From medical claims representing >25% of U.S. vaccinations. Surveillance Data, Inc. Data on file (Electronic physician claims database). October MKT Disease Activity Peaks Well After the Traditional Immunization Season Vaccination Visits 4,000,000 3,500,000 3,000, week gap between peaks Diagnosis Visits 250, ,000 2,500,000 2,000,000 1,500,000 1,000,000 Influenza vaccination visits a (three-year average) Influenza diagnosis visits a (three-year average) 150, ,000 50, , Sep Oct Nov Dec Jan Feb Mar Reference: a From medical claims data representing >25% of U.S. vaccinations. Surveillance Data, Inc. Data on file (Electronic physician claims database). October MKT

15 Visits to Health-care Providers by Unimmunized Persons During Influenza Season Patient Visits 4,000,000 3,500,000 Diagnosis Visits 250,000 3,000, ,000 2,500,000 2,000,000 1,500,000 Visits to health-care providers by unimmunized high-risk patients a (two-year average) 150, ,000 1,000, ,000 50,000 0 Sep Oct Nov Dec Jan Feb Mar 0 Reference: a From medical claims data representing >25% of U.S. vaccinations. Surveillance Data, Inc. Data on file (Electronic physician claims database). October MKT Influenza Vaccination Opportunities Extend Well Beyond the Traditional Immunization Season Patient Visits 4,000,000 3,500,000 Diagnosis Visits 250,000 3,000, ,000 2,500,000 2,000,000 1,500,000 Influenza Vaccination Opportunities 150, ,000 1,000, ,000 50,000 0 Sep Oct Nov Dec Jan Feb Mar 0 Surveillance Data, Inc. Data on file (Electronic physician claims database). October MKT

16 OTHER MEASURES T0 CONTROL INFLUENZA Sick Persons Should Stay Home Advise those that have signs of fever and influenza like illness to stay home Sick people are advised to stay home for 24 hours after the fever has resolved Expect people to be out for 3-5 days Develop flexible sick leave policies Cover Cough and Sneezes Because viruses are predominantly spread from respiratory droplets, properly covering coughs and sneezes can help 16

17 Improve Hand Hygiene Provide information that encourages hand hygiene Soap and water and alcohol-based hand sanitizers both work well Make sure that supplies are maintained and if feasible, make sure hand sanitizers are placed in multiple locations Clean Surfaces that are Likely to have Frequent Hand Contact Frequently clean commonly touched surfaces such as workstations, countertops, doorknobs, phones Use cleaning agents that are normally used no further disinfection is recommended Anti Viral Drugs If you get the flu, antiviral drugs can treat your illness. Antiviral drugs are different from antibiotics. They are prescription medicines (pills, liquid or an inhaled powder) and are not available over-the-counter. Antiviral drugs can make illness milder and shorten the time you are sick. They may also prevent serious flu complications. For people with high risk factors, treatment with an antiviral drug can mean the difference between having a milder illness versus a very serious illness that could result in a hospital stay. Studies show that flu antiviral drugs work best for treatment when they are started within 2 days of getting sick, but starting them later can still be helpful, especially if the sick person has a high-risk health or is very sick from the flu. Follow your doctor s instructions for taking this drug. Flu-like symptoms include fever, cough, sore throat, runny or stuffy nose, body aches, headache, chills and fatigue. Some people also may have vomiting and diarrhea. People may be infected with the flu, and have respiratory symptoms without a fever. 17

18 Dispelling Myths About Influenza Influenza isn t a serious disease. The flu shot can cause the flu. The shot does not work. Dispelling Myths About Influenza The side effects of the vaccine are worse than influenza. Only older people need the vaccine. You must get the vaccine before December in order to benefit. 18