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Influenza and Influenza Vaccine Epidemiology and Prevention of Vaccine- Preventable Diseases National Center for Immunization and Respiratory Diseases.

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Presentation on theme: "Influenza and Influenza Vaccine Epidemiology and Prevention of Vaccine- Preventable Diseases National Center for Immunization and Respiratory Diseases."— Presentation transcript:

1 Influenza and Influenza Vaccine Epidemiology and Prevention of Vaccine- Preventable Diseases National Center for Immunization and Respiratory Diseases Centers for Disease Control and Prevention Revised May 2009

2 Influenza Antigenic Changes Antigenic Shift – major change, new subtype – caused by exchange of gene segments – may result in pandemic Example of antigenic shift – H2N2 virus circulated in – H3N2 virus appeared in 1968 and completely replaced H2N2 virus

3 Influenza Antigenic Changes Antigenic Drift – minor change, same subtype – caused by point mutations in gene – may result in epidemic Example of antigenic drift – in , A/Panama/2007/99 (H3N2) virus was dominant – A/Fujian/411/2002 (H3N2) appeared in late 2003 and caused widespread illness in

4 Influenza Clinical Features Incubation period 2 days (range 1-4 days) Abrupt onset of fever, myalgia, sore throat, nonproductive cough, headache Severity of illness depends on prior experience with related variants

5 Influenza Complications Pneumonia – secondary bacterial – primary influenza viral Reye syndrome Myocarditis Death per 1,000 cases

6 Impact of Influenza-United States, Approximately 36,000 influenza- associated deaths during each influenza season Persons 65 years of age and older account for more than 90% of deaths Higher mortality during seasons when influenza type A (H3N2) viruses predominate

7 Highest rates of complications and hospitalization among young children and person 65 years and older Average of more than 200,000 influenza-related excess hospitalizations 57% of hospitalizations among persons younger than 65 years of age Greater number of hospitalizations during type A (H3N2) epidemics Impact of Influenza-United States,

8 Influenza Among School- Aged Children School-aged children – typically have the highest attack rates during community outbreaks of influenza – serve as a major source of transmission of influenza within communities

9 Month of Peak Influenza Activity United States, % 19% 47% 13% 3% MMWR 2006;55:22

10 Influenza Vaccines Inactivated subunit (TIV) – intramuscular – trivalent – split virus and subunit types – duration of immunity 1 year or less Live attenuated vaccine (LAIV) – intranasal – trivalent – duration of immunity at least 1 year

11 Inactivated Influenza Vaccine Efficacy 70%-90% effective among healthy persons younger than 65 years of age 30%-40% effective among frail elderly persons 50%-60% effective in preventing hospitalization 80% effective in preventing death

12 Influenza and Complications Among Nursing Home Residents Vaccinated*Unvaccinated RR=1.9 RR=2.0RR=2.5RR=4.2 *Inactivated influenza vaccine. Genesee County, MI,

13 LAIV Efficacy in Healthy Children 87% effective against culture-confirmed influenza in children 5-7 years old 27% reduction in febrile otitis media (OM) 28% reduction in OM with accompanying antibiotic use Decreased fever and OM in vaccine recipients who developed influenza

14 LAIV Efficacy in Healthy Adults 20% fewer severe febrile illness episodes 24% fewer febrile upper respiratory illness episodes 27% fewer lost work days due to febrile upper respiratory illness 18%-37% fewer days of healthcare provider visits due to febrile illness 41%-45% fewer days of antibiotic use

15 Timing of Influenza Vaccine Programs Influenza activity can occur as early as October In more than 80% of seasons since 1976, peak influenza activity has not occurred until January or later In more than 60% of seasons the peak was in February or later

16 Timing of Influenza Vaccine Programs Providers should begin offering vaccine soon after it becomes available, if possible by October To avoid missed opportunities for vaccination, providers should offer vaccine during routine healthcare visits or during hospitalizations whenever vaccine is available

17 Inactivated Influenza Vaccine Schedule Age Group 6-35 mos 3-8 yrs >9 yrs Dose 0.25 mL 0.50 mL No. Doses 1* or 2 1 *Only one dose is needed if the child received 2 doses of influenza vaccine during the previous influenza season

18 Influenza Vaccination of Children Children 6 months through 8 years of age who did not receive the recommended second dose of influenza vaccine in the initial year that they received influenza vaccine should receive 2 doses during the next influenza season* Children 6 months through 8 years of age who are being vaccinated two or more seasons after receiving an influenza vaccine for the first time should receive a single annual dose, regardless of the number of doses administered previously *applies only to the influenza season that follows the first season that a child younger than 9 years receives influenza vaccine

19 Influenza Vaccination Schedule All children younger than 9 years receiving seasonal influenza vaccine for the first time this season should receive 2 doses, separated by 4 weeks Children younger than 9 years who received a seasonal vaccine for the first time last season but who received only 1 dose should receive 2 doses this season MMWR 2010;59 (early release) From the Immunization Update 2010 webcast (originally broadcast August 5, 2010

20 Influenza Vaccination Schedule Children younger than 9 years who did not receive at least 1 dose of a 2009 monovalent vaccine should receive 2 doses of seasonal vaccine this season Children younger than 9 years whose 2009 pandemic vaccine history is not known should receive 2 doses this season MMWR 2010;59 (early release) From the Immunization Update 2010 webcast (originally broadcast August 5, 2010

21 Live Attenuated Influenza Vaccine Indications Healthy*, nonpregnant persons 2 through 49 years of age, including – healthy children – healthcare personnel – persons in close contact with high- risk groups – persons who want to reduce their risk of influenza *Persons who do not have medical conditions that increase their risk for complications of influenza

22 Fluzone High-Dose TIV Approved only for persons 65 years of age or older Each dose contains 4 times as much hemagglutinin as the regular formulation of Fluzone for adults ACIP has not expressed a preference for the high dose Fluzone formulation or any other inactivated vaccine for use in persons 65 years and older MMWR 2010;59 (early release) From the Immunization Update 2010 webcast (originally broadcast August 5, 2010

23 Inactivated Influenza Vaccine Adverse Reactions Local reactions15%-20% Fever, malaisenot common Allergic reactionsrare Neurologicalvery rare reactions

24 Live Attenuated Influenza Vaccine Adverse Reactions Children – no significant increase in URI symptoms, fever, or other systemic symptoms – significantly increased risk of asthma or reactive airways disease in children months of age Adults – significantly increased rate of cough, runny nose, nasal congestion, sore throat, and chills reported among vaccine recipients – no increase in the occurrence of fever No serious adverse reactions identified

25 Inactivated Influenza Vaccine Contraindications and Precautions Severe allergic reaction to a vaccine component (e.g., egg) or following a prior dose of vaccine Moderate or severe acute illness History of Guillian Barré syndrome within 6 weeks following a previous dose of TIV (precaution)

26 Live Attenuated Influenza Vaccine Contraindications and Precautions Children younger than 2 years of age* Persons 50 years of age or older* Persons with chronic medical conditions* Children and adolescents receiving long-term aspirin therapy* *These persons should receive inactivated influenza vaccine

27 Live Attenuated Influenza Vaccine Contraindications and Precautions Immunosuppression from any cause* Pregnant women* Severe (anaphylactic) allergy to egg or other vaccine components History of Guillian-Barré syndrome Children younger than 5 years with recurrent wheezing* Moderate or severe acute illness *These persons should receive inactivated influenza vaccine


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