EFFICACY AND EFFECTIVINESS OF INACTIVED INFLUENZA VIRUS VACCINE

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EFFICACY AND EFFECTIVINESS OF INACTIVED
INFLUENZA VIRUS VACCINE
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Factors influencing vaccine efficacy

• Closeness of the match between the vaccine strain
  and the circulating virus
• Age of vaccinee older people do not respond as
  well
• Health of the vaccinee people with chronic
  illnesses and immune system disorders do not
  respond as well as healthy individuals
• Number of vaccinations regular annual
  vaccinations improve the protection compared with
  the first year of vaccination
• Type of vaccine used

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Efficacy of influenza vaccination in healthy
adults

• Prevention of influenza infection
• Recommended inactivated parenteral vaccines
• Efficacy 70
• Effectiveness 25
• Recommended live aerosol vaccines
• Efficacy 48
• Effectiveness 15

Demicheli V et al. Cochrane Database Syst Rev
2004 3 CD001269.
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Efficacy of influenza vaccination in elderly and
high-risk persons

• Prevention of illness and death
• Among high-risk adults (e.g. patients with
  chronic cardiovascular, respiratory or renal
  disease) 1864 years, vaccination prevented1
• 78 of deaths
• 87 of hospitalisations
• 26 of GP visits
• Among elderly individuals (gt 65 years),
  vaccination prevented1
• 50 of deaths
• 48 of hospitalisations

1. Hak E et al. Arch Intern Med 2005 165 27480
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Efficacy of influenza vaccination in elderly and
high-risk persons

• Prevention of illness and death
• Among community-dwelling elderly individuals,
  influenza vaccination prevented 1 death for every
  302 vaccinees at vaccination coverage between 64
  and 74

Voordouw AC et al. JAMA 2004 292 208995.
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Efficacy of influenza vaccination in elderly
persons

• In a meta-analysis of 20 cohort studies, pooled
  estimates of vaccine efficacy demonstrated
  prevention of morbidity and mortality during the
  influenza season
• Respiratory illness 56
• Pneumonia 53
• Hospitalisation 50
• Death 68

The studies confirm the effectivenessof
influenza vaccine
Gross PA et al. Ann Intern Med 1995 123 51827.
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Influenza deaths versus vaccination history
WHO Collaborating Centre for Influenza, Melbourne.
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Influenza vaccination inpatients with CHD

• Case control study of 218 patients with coronary
  heart disease (CHD) during the 199798 influenza
  season in the USA
• Efficacy of influenza vaccine in reducing the
  risk of recurrent myocardial infarction (MI) in
  patients with CHD

Vaccination associated with a reduced risk of
recurrent MI
Past and current influenza vaccination
reducesthe risk of recurrent MI in CHD patients
Naghavi M et al. Circulation 2000 102 303945.
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Influenza vaccination inindividuals with asthma

• No significant increase in asthma exacerbations
  in the 2 weeks following influenza vaccination
• Based on pooled results of two trialsinvolving
  2306 individuals with asthmain a Cochrane review
• No significant reduction in influenza-related
  asthma exacerbations
• Based on a recent study of 696 childrenwith
  asthma

Cates CJ et al. Cochrane Database Syst Rev 2004
2 CD000364.
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Years of life bought forUS1 million (1990
dollars)

• Pap smear every 3 years 52 life-years
• Bypass surgery for left main 134
  life-yearscoronary artery disease
• Pneumococcal pneumonia 100 life-years
  vaccination
• Influenza vaccination 11,100 life-years

Influenza vaccination is a highly cost-effective
healthcare intervention
Russell LB. Health Aff (Millwood) 1992 11 1629.
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By courtesy of APACIAsia-Pacific Advisory
Committee on influenzawww.apaci-flu.com