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Vaccination: Cornerstone of Influenza Control

Vaccination coverage

For a long time, doubts and misconceptions about the risk–benefit ratio of influenza vaccination have hampered the implementation of recommended policies for influenza vaccination. However, in recent years, influenza vaccination has become a prominent issue on the public-health agenda in an increasing number of countries. 10 x The Macroepidemiology of Influenza Vaccination (MIV) Study Group. The macroepidemiology of influenza vaccination in 56 countries, 1997–2003. Vaccine 23 (2005) (5133 - 5143) Many developed as well as developing countries have now adopted formal recommendations on influenza vaccination for specific target groups. Although these recommendations are still a matter of national responsibility, they have nonetheless become increasingly uniform, particularly throughout Western Europe, North America, Australia, New Zealand and Japan. In addition, in 2000, the WHO has issued for the first time a formal recommendation for the use of inactivated vaccines for the prevention of influenza. 9 x World Health Organization. Influenza vaccines. Wkly Epidemiol Rec 75 (2000) (281 - 288)

Recommendations for influenza vaccination

Table 17 presents the recommendations for influenza vaccination adopted in most countries. The elderly represent the primary target group. 10, x The Macroepidemiology of Influenza Vaccination (MIV) Study Group. The macroepidemiology of influenza vaccination in 56 countries, 1997–2003. Vaccine 23 (2005) (5133 - 5143) 11 x World Health Organization. Influenza vaccines. Wkly Epidemiol Rec 77 (2002) (230 - 239) This recommendation follows the increased susceptibility of the elderly for infectious diseases in general, which may be explained, at least partly, by a gradual decline in immune competence with age, particularly at the level of T cell function (see Chapter 4). The recommendation is also based on the proven clinical efficacy and effectiveness of flu vaccination of the elderly. 12 x KL Nichol. The efficacy, effectiveness and cost-effectiveness of inactivated influenza virus vaccines. Vaccine 21 (2003) (1769 - 1775) Crossref. In most countries, flu vaccination is recommended for all individuals above 60 or 65 years of age. In a few countries, including the USA and Belgium, the age recommendation includes everyone over the age of 50 years due to the increased prevalence of high-risk conditions for influenza illness among people over 50 years of age. In general, an age-based strategy is easier to implement than a targeted risk-group strategy. This is particularly relevant because of the relatively low vaccine coverage rates in patients at risk who are younger than 65 years of age.27, 28, and 29 x MW Kroneman, GA van Essen, MA Tacken, et al.. Does a population survey provide reliable influenza vaccine uptake rates among high-risk groups? A case-study of The Netherlands. Vaccine 22 (2004) (2163 - 2170) Crossref. x M Kroneman, GA van Essen, W John Paget. Influenza vaccination coverage and reasons to refrain among high-risk persons in four European countries. Vaccine 24 (2006) (622 - 628) Crossref. x TD Szucs, D Muller. Influenza vaccination coverage rates in five European countries – a population-based cross-sectional analysis of two consecutive influenza seasons. Vaccine 23 (2005) (5055 - 5063) Crossref. Currently, more countries are considering lowering the age limit for vaccination recommendation. In recent studies, the cost-effectiveness of an expanded vaccination policy, including all individuals over 50 years of age, has been established for a number of European countries. 30, x J Chancellor. Lowering the age threshold for routine influenza vaccination to 50 years: cost-effectiveness analysis for European countries. Vaccine (2006) in press. 31 x DA Turner, AJ Wailoo, NJ Cooper, et al.. The cost-effectiveness of influenza vaccination of healthy adults 50–64 years of age. Vaccine 24 (2006) (1035 - 1043) Crossref. Vaccination is also quite uniformly recommended for individuals with specific medical conditions, including cardiovascular, pulmonary and renal disease, diabetes and immunodeficiency. 10 x The Macroepidemiology of Influenza Vaccination (MIV) Study Group. The macroepidemiology of influenza vaccination in 56 countries, 1997–2003. Vaccine 23 (2005) (5133 - 5143) Furthermore, many countries recommend flu vaccination for nursing-home residents, health-care workers and household contacts of high-risk individuals. 10 x The Macroepidemiology of Influenza Vaccination (MIV) Study Group. The macroepidemiology of influenza vaccination in 56 countries, 1997–2003. Vaccine 23 (2005) (5133 - 5143) In addition, there is an increasing awareness of the potential benefits of influenza vaccination of younger healthy (working) adults, 12, x KL Nichol. The efficacy, effectiveness and cost-effectiveness of inactivated influenza virus vaccines. Vaccine 21 (2003) (1769 - 1775) Crossref. 13 x KL Nichol. Efficacy/clinical effectiveness of inactivated influenza virus vaccines in adults. KG Nicholson, RG Webster, AJ Hay (Eds.) Textbook of Influenza (Blackwell Science, 1998) (358 - 372) pregnant women, 32 x Centers for Disease Control and Prevention. Influenza vaccination in pregnancy: practices among obstetrician-gynecologists – United States, 2003–04 influenza season. MMWR 54 (2005) (1050 - 1052) (www.cdc.gov/mmwr/preview/mmwrhtml/mm5441a4.htm) and children. 12, x KL Nichol. The efficacy, effectiveness and cost-effectiveness of inactivated influenza virus vaccines. Vaccine 21 (2003) (1769 - 1775) Crossref. 33, 34, and 35 x T Heikkinen, R Booy, M Campins, et al.. Should healthy children be vaccinated against influenza? A consensus report of the Summits of Independent European Vaccination Experts. Eur J Pediatr 21 (2005) (1 - 6) x T Heikkinen, O Ruuskanen. Influenza vaccines in healthy children (letter to the editor). Lancet 365 (2005) (2086 - 2087) Crossref. x YZ Ghendon, AN Kaira, GA Elshina. The effect of mass influenza immunization in children on the morbidity of the unvaccinated elderly. Epidemiol Infect 134 (2006) (71 - 78)

Table 17 Recommendations for influenza vaccination of specific target groups adopted in most European countries. source: Source: The Macroepidemiology of Influenza Vaccination (MIV) Study Group. The macroepidemiology of influenza vaccination in 56 countries, 1997–2003. Vaccine 2005; 23: 5133–5143. 10 x The Macroepidemiology of Influenza Vaccination (MIV) Study Group. The macroepidemiology of influenza vaccination in 56 countries, 1997–2003. Vaccine 23 (2005) (5133 - 5143)

Influenza vaccination recommendations in European countries
  • People aged >65 years.
  • Residents of nursing homes and other long-term care facilities.
  • Adults and children with chronic pulmonary disorders.
  • Adults and children with chronic cardiovascular disorders.
  • Those who have required regular medical follow-up or hospitalization during the preceding year because of
    • chronic metabolic diseases (including diabetes mellitus),
    • renal dysfunction,
    • haemoglobinopathies, or
    • immunosuppression (including immunosuppression caused by medications or by human immunodeficiency virus).
  • Children and teenagers (aged 6 months to 18 years) who are receiving long-term aspirin therapy and therefore might be at risk for developing influenza infection.
  • Vaccination of health-care workers and others in close contact with persons at high risk, including household members, is recommended.

References in context

  • Table 17 presents the recommendations for influenza vaccination adopted in most countries.
    Go to context

Current use of influenza vaccines

Along with the implementation of formal recommendations for flu vaccination in an increasing number of countries, the use of influenza vaccines has increased considerably in the last decade or so. The most dramatic changes in this respect have occurred in Korea, Latin America, Japan and some central and eastern European countries. 10 x The Macroepidemiology of Influenza Vaccination (MIV) Study Group. The macroepidemiology of influenza vaccination in 56 countries, 1997–2003. Vaccine 23 (2005) (5133 - 5143) Figure 27 presents a survey of influenza vaccine distribution in 56 developed and rapidly developing countries in 1997 and 2003.

Figure 27 Use of influenza vaccine in 56 developed and developing countries in the period 1997–2003. source: Reproduced from The Macroepidemiology of Influenza Vaccination (MIV) Study Group. The macroepidemiology of influenza vaccination in 56 countries, 1997–2003. Vaccine 2005; 23: 5133–5143 10 x The Macroepidemiology of Influenza Vaccination (MIV) Study Group. The macroepidemiology of influenza vaccination in 56 countries, 1997–2003. Vaccine 23 (2005) (5133 - 5143) with permission from Elsevier.

f08-27-9780723434337

References in context

  • The most dramatic changes in this respect have occurred in Korea, Latin America, Japan and some central and eastern European countries.10 Figure 27 presents a survey of influenza vaccine distribution in 56 developed and rapidly developing countries in 1997 and 2003.
    Go to context

As mentioned above, the total number of influenza vaccine doses distributed annually worldwide has increased in recent years to an estimated level of 300 million in 2003. About 60% of these doses are distributed among North America and Western Europe and 40% goes to the rest of the world. In 1994, these figures were 80% and 20%, respectively. 10 x The Macroepidemiology of Influenza Vaccination (MIV) Study Group. The macroepidemiology of influenza vaccination in 56 countries, 1997–2003. Vaccine 23 (2005) (5133 - 5143) This trend indicates that many countries, including developing countries, are moving towards implementation of measures for influenza prevention and control on an annual basis.

However, despite the increased vaccine use, recent surveys in Europe show that the coverage rates in target populations are still far from the WHO-recommended 75% in 2010. 29, x TD Szucs, D Muller. Influenza vaccination coverage rates in five European countries – a population-based cross-sectional analysis of two consecutive influenza seasons. Vaccine 23 (2005) (5055 - 5063) Crossref. 36 x Resolution WHA56.19. Prevention and control of influenza pandemics and annual epidemics (Fifty-Sixth World Health Assembly, Geneva, 19–28 May 2003) (www.who.int/gb/ebwha/pdf_files/WHA56/ea56r19.pdf) The current coverage rates range from 18% (Poland) to 67% (Spain) for the elderly and from 3% to 40% for various risk groups in younger populations. 28, x M Kroneman, GA van Essen, W John Paget. Influenza vaccination coverage and reasons to refrain among high-risk persons in four European countries. Vaccine 24 (2006) (622 - 628) Crossref. 29, x TD Szucs, D Muller. Influenza vaccination coverage rates in five European countries – a population-based cross-sectional analysis of two consecutive influenza seasons. Vaccine 23 (2005) (5055 - 5063) Crossref. 37 x SA Smith, GA Poland. The use of influenza and pneumococcal vaccines in people with diabetes (technical review). Diabetes Care 23 (2000) (95 - 108) Crossref. In the USA, only 35% of adults between the ages of 18 and 64 years who are at risk for serious complications due to influenza were being vaccinated in 2003. 38 x Centers for Disease Control and Prevention. Influenza vaccination levels among person aged ≥65 years and among persons aged 18–64 years with high-risk conditions – United States, 2003. MMWR 54 (2005) (1045 - 1049) (www.cdc.gov/mmwr/preview/mmwrhtml/mm5441a3.htm) The implication of these findings is that many elderly and at-risk patients are not receiving the best possible protective treatment to prevent influenza or minimize the consequences of an influenza infection. Based on current scientific evidence of vaccine efficacy and effectiveness, 12 x KL Nichol. The efficacy, effectiveness and cost-effectiveness of inactivated influenza virus vaccines. Vaccine 21 (2003) (1769 - 1775) Crossref. serious efforts are to be made towards compliance with the target vaccination rates recommended by the WHO for 2010. 36 x Resolution WHA56.19. Prevention and control of influenza pandemics and annual epidemics (Fifty-Sixth World Health Assembly, Geneva, 19–28 May 2003) (www.who.int/gb/ebwha/pdf_files/WHA56/ea56r19.pdf)

The single most important factor influencing the use of influenza vaccine is whether it is recommended by the doctor. Therefore, primary-care physicians and other health-care workers play a major role in implementing influenza vaccination programmes, 29 x TD Szucs, D Muller. Influenza vaccination coverage rates in five European countries – a population-based cross-sectional analysis of two consecutive influenza seasons. Vaccine 23 (2005) (5055 - 5063) Crossref. as discussed in more detail in the last paragraph of this chapter.

 
x

Figure 27 Use of influenza vaccine in 56 developed and developing countries in the period 1997–2003. source: Reproduced from The Macroepidemiology of Influenza Vaccination (MIV) Study Group. The macroepidemiology of influenza vaccination in 56 countries, 1997–2003. Vaccine 2005; 23: 5133–5143 10 x The Macroepidemiology of Influenza Vaccination (MIV) Study Group. The macroepidemiology of influenza vaccination in 56 countries, 1997–2003. Vaccine 23 (2005) (5133 - 5143) with permission from Elsevier.

f08-27-9780723434337

References in context

  • The most dramatic changes in this respect have occurred in Korea, Latin America, Japan and some central and eastern European countries.10 Figure 27 presents a survey of influenza vaccine distribution in 56 developed and rapidly developing countries in 1997 and 2003.
    Go to context

Table 17 Recommendations for influenza vaccination of specific target groups adopted in most European countries. source: Source: The Macroepidemiology of Influenza Vaccination (MIV) Study Group. The macroepidemiology of influenza vaccination in 56 countries, 1997–2003. Vaccine 2005; 23: 5133–5143. 10 x The Macroepidemiology of Influenza Vaccination (MIV) Study Group. The macroepidemiology of influenza vaccination in 56 countries, 1997–2003. Vaccine 23 (2005) (5133 - 5143)

Influenza vaccination recommendations in European countries
  • People aged >65 years.
  • Residents of nursing homes and other long-term care facilities.
  • Adults and children with chronic pulmonary disorders.
  • Adults and children with chronic cardiovascular disorders.
  • Those who have required regular medical follow-up or hospitalization during the preceding year because of
    • chronic metabolic diseases (including diabetes mellitus),
    • renal dysfunction,
    • haemoglobinopathies, or
    • immunosuppression (including immunosuppression caused by medications or by human immunodeficiency virus).
  • Children and teenagers (aged 6 months to 18 years) who are receiving long-term aspirin therapy and therefore might be at risk for developing influenza infection.
  • Vaccination of health-care workers and others in close contact with persons at high risk, including household members, is recommended.

References in context

  • Table 17 presents the recommendations for influenza vaccination adopted in most countries.
    Go to context

References

Label Authors Title Source Year
9

References in context


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  • Go to context

  • The safety record of inactivated influenza vaccines is excellent.9,14 Hundreds of millions of vaccine doses are distributed worldwide each year, adverse effects being extremely rare.
    Go to context

  • These strains are included in the vaccines on recommendation of the WHO.8,9 This recommendation is based on an extensive review of epidemiological data and antigenic and genetic analyses of virus isolates by the four WHO Collaborating Centres.
    Go to context

  • For a long time, doubts and misconceptions about the risk–benefit ratio of influenza vaccination have hampered the implementation of recommended policies for influenza vaccination.
    Go to context

  • Inactivated influenza vaccines have an excellent safety record.9,14 Currently, about 300 million vaccine doses are being administered annually around the globe,10 and the overall rate of adverse reactions is extremely low.
    Go to context

World Health Organization. Influenza vaccines. Wkly Epidemiol Rec 75 (2000) (281 - 288) 2000
10

References in context


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  • Go to context


  • Go to context

  • Vaccination results in reductions of influenza-related respiratory illness and numbers of physician visits among all age groups, and in lower hospitalization rates and deaths among the elderly and patients at risk for serious complications of influenza.12,13 Vaccination coverage among target groups has increased considerably in recent years10 as the awareness of the impact of influenza is growing and influenza has become an important issue on the public-health agenda in many countries.15,16 However, the use of available influenza vaccines is still far from optimal.
    Go to context

  • However, in recent years, influenza vaccination has become a prominent issue on the public-health agenda in an increasing number of countries.10 Many developed as well as developing countries have now adopted formal recommendations on influenza vaccination for specific target groups.
    Go to context

  • The elderly represent the primary target group.10,11 This recommendation follows the increased susceptibility of the elderly for infectious diseases in general, which may be explained, at least partly, by a gradual decline in immune competence with age, particularly at the level of T cell function (see Chapter 4).
    Go to context

  • The elderly represent the primary target group.10,11 This recommendation follows the increased susceptibility of the elderly for infectious diseases in general, which may be explained, at least partly, by a gradual decline in immune competence with age, particularly at the level of T cell function (see Chapter 4).
    Go to context

  • The elderly represent the primary target group.10,11 This recommendation follows the increased susceptibility of the elderly for infectious diseases in general, which may be explained, at least partly, by a gradual decline in immune competence with age, particularly at the level of T cell function (see Chapter 4).
    Go to context

  • The most dramatic changes in this respect have occurred in Korea, Latin America, Japan and some central and eastern European countries.10 Figure 27 presents a survey of influenza vaccine distribution in 56 developed and rapidly developing countries in 1997 and 2003.
    Go to context

  • In 1994, these figures were 80% and 20%, respectively.10 This trend indicates that many countries, including developing countries, are moving towards implementation of measures for influenza prevention and control on an annual basis.
    Go to context

  • Inactivated influenza vaccines have an excellent safety record.9,14 Currently, about 300 million vaccine doses are being administered annually around the globe,10 and the overall rate of adverse reactions is extremely low.
    Go to context


  • Go to context


  • Go to context

  • To improve the vaccination coverage rates in target groups, in accordance with WHO recommendations,10,11,36 it is important that existing national vaccination policies are effectively implemented.
    Go to context

The Macroepidemiology of Influenza Vaccination (MIV) Study Group. The macroepidemiology of influenza vaccination in 56 countries, 1997–2003. Vaccine 23 (2005) (5133 - 5143) 2005
11

References in context


  • Go to context

  • The elderly represent the primary target group.10,11 This recommendation follows the increased susceptibility of the elderly for infectious diseases in general, which may be explained, at least partly, by a gradual decline in immune competence with age, particularly at the level of T cell function (see Chapter 4).
    Go to context


  • Go to context

  • To improve the vaccination coverage rates in target groups, in accordance with WHO recommendations,10,11,36 it is important that existing national vaccination policies are effectively implemented.
    Go to context

World Health Organization. Influenza vaccines. Wkly Epidemiol Rec 77 (2002) (230 - 239) 2002
12

References in context


  • Go to context


  • Go to context


  • Go to context

  • Vaccination results in reductions of influenza-related respiratory illness and numbers of physician visits among all age groups, and in lower hospitalization rates and deaths among the elderly and patients at risk for serious complications of influenza.12,13 Vaccination coverage among target groups has increased considerably in recent years10 as the awareness of the impact of influenza is growing and influenza has become an important issue on the public-health agenda in many countries.15,16 However, the use of available influenza vaccines is still far from optimal.
    Go to context

  • The recommendation is also based on the proven clinical efficacy and effectiveness of flu vaccination of the elderly.12 In most countries, flu vaccination is recommended for all individuals above 60 or 65 years of age.
    Go to context

  • The recommendation is also based on the proven clinical efficacy and effectiveness of flu vaccination of the elderly.12 In most countries, flu vaccination is recommended for all individuals above 60 or 65 years of age.
    Go to context

  • The recommendation is also based on the proven clinical efficacy and effectiveness of flu vaccination of the elderly.12 In most countries, flu vaccination is recommended for all individuals above 60 or 65 years of age.
    Go to context

  • However, despite the increased vaccine use, recent surveys in Europe show that the coverage rates in target populations are still far from the WHO-recommended 75% in 2010.29,36 The current coverage rates range from 18% (Poland) to 67% (Spain) for the elderly and from 3% to 40% for various risk groups in younger populations.28,29,37 In the USA, only 35% of adults between the ages of 18 and 64 years who are at risk for serious complications due to influenza were being vaccinated in 2003.38 The implication of these findings is that many elderly and at-risk patients are not receiving the best possible protective treatment to prevent influenza or minimize the consequences of an influenza infection.
    Go to context

  • As a result, many clinical studies have now produced consistent data showing the clear-cut benefits of influenza vaccination.12,13,33,35,40 Since the elderly comprise by far the largest target population for flu vaccination, the majority of studies evaluating the benefits of vaccination have been conducted among people in this age group; these will be discussed in more detail below.
    Go to context

  • In evaluating the outcome of influenza vaccination, a distinction is often made between vaccine efficacy per se and the clinical effectiveness of vaccination.12,13 Vaccine efficacy is defined as the reduction in the rate of laboratory-confirmed influenza among vaccinated compared to non-vaccinated individuals.
    Go to context

  • It is defined as the reduction of clinically relevant, but not necessarily influenza-specific, disease in a “real-life” situation, including all influenza-like illness (ILI), hospitalizations due to pneumonia from all causes or death from all causes.12,13,40 As this parameter includes – by definition – disease that is not caused by the influenza virus, clinical effectiveness of vaccination is generally estimated to be lower than the actual vaccine efficacy, as illustrated by the hypothetical example presented in Figure 28.13 Therefore, clinical effectiveness should not be confused for vaccine efficacy, as this may result in a substantial underestimation of the actual performance of the vaccine.
    Go to context

  • Numerous studies have convincingly demonstrated the clinical benefits of influenza vaccination in the elderly.12,13,40,48,49 For example, in a large study in the USA, spanning two influenza seasons (1998–2000) and involving 300,000 community-dwelling elderly people (≥65 years), influenza vaccination was performed in 55.5–59.7% of the population.
    Go to context

  • Economic evaluations, conducted in many different countries, have indicated that vaccination of senior citizens against influenza is always cost-effective and frequently cost-saving.12,13 For example, in a 6-year study carried out in Minnesota, USA, influenza vaccination of nursing-home residents was associated with an average net saving of $73 per person as a result of reductions in direct medical costs.12 Vaccination appears to be cost-effective or even cost-saving for both healthy senior citizens and high-risk elderly with underlying chronic medical conditions.
    Go to context

  • Economic evaluations, conducted in many different countries, have indicated that vaccination of senior citizens against influenza is always cost-effective and frequently cost-saving.12,13 For example, in a 6-year study carried out in Minnesota, USA, influenza vaccination of nursing-home residents was associated with an average net saving of $73 per person as a result of reductions in direct medical costs.12 Vaccination appears to be cost-effective or even cost-saving for both healthy senior citizens and high-risk elderly with underlying chronic medical conditions.
    Go to context


  • Go to context

  • This is why there is an increasing awareness of the potential benefits of vaccination of working adults.12,13 Several prospective clinical studies have demonstrated the efficacy of inactivated influenza vaccines among healthy younger adults.
    Go to context

  • As demonstrated by a number of studies, conducted in different countries, vaccination significantly reduces illness, absenteeism and influenza-related costs for healthy adults in the work place.12,13 Indeed, vaccination reduces upper respiratory tract and influenza-like illnesses from all causes by approximately 30%, related physician visits by >40% and work loss by >35% (Table 20).60,61 Accordingly, cost–benefit analyses, based on clinical trials or on modelling, have shown that vaccination of healthy working adults is cost-effective and in many cases cost-saving, provided that indirect costs associated with work absenteeism (see Chapter 6) are explicitly taken into account.62 For example, trials conducted in the USA have shown that – with an average cost for vaccine production and administration of $20 – the net saving would be $23 per person vaccinated.63 In another study comparing 131 vaccinated employees from six textile plants in North Carolina, USA, with 131 age- and gender-matched non-vaccinated controls from different plants, the “cost per saved lost work day” was $22.36, resulting in an overall saving of $2.58 per dollar invested in the vaccination programme.64 Other, model-based, studies also indicate that vaccinating working adults would be cost-saving.12 While recent international guidelines for pharmacoeconomic analyses do explicitly recommend the inclusion of production gains and losses,62 also when such indirect costs are not taken into account, vaccination of adults below the age of 65 turns out to be highly cost-effective.
    Go to context

  • As demonstrated by a number of studies, conducted in different countries, vaccination significantly reduces illness, absenteeism and influenza-related costs for healthy adults in the work place.12,13 Indeed, vaccination reduces upper respiratory tract and influenza-like illnesses from all causes by approximately 30%, related physician visits by >40% and work loss by >35% (Table 20).60,61 Accordingly, cost–benefit analyses, based on clinical trials or on modelling, have shown that vaccination of healthy working adults is cost-effective and in many cases cost-saving, provided that indirect costs associated with work absenteeism (see Chapter 6) are explicitly taken into account.62 For example, trials conducted in the USA have shown that – with an average cost for vaccine production and administration of $20 – the net saving would be $23 per person vaccinated.63 In another study comparing 131 vaccinated employees from six textile plants in North Carolina, USA, with 131 age- and gender-matched non-vaccinated controls from different plants, the “cost per saved lost work day” was $22.36, resulting in an overall saving of $2.58 per dollar invested in the vaccination programme.64 Other, model-based, studies also indicate that vaccinating working adults would be cost-saving.12 While recent international guidelines for pharmacoeconomic analyses do explicitly recommend the inclusion of production gains and losses,62 also when such indirect costs are not taken into account, vaccination of adults below the age of 65 turns out to be highly cost-effective.
    Go to context

  • Finally, vaccination of children appears to be highly cost-effective and in many cases cost-saving.
    Go to context

KL Nichol. The efficacy, effectiveness and cost-effectiveness of inactivated influenza virus vaccines. Crossref. Vaccine 21 (2003) (1769 - 1775) 2003
13

References in context


  • Go to context


  • Go to context

  • Vaccination results in reductions of influenza-related respiratory illness and numbers of physician visits among all age groups, and in lower hospitalization rates and deaths among the elderly and patients at risk for serious complications of influenza.12,13 Vaccination coverage among target groups has increased considerably in recent years10 as the awareness of the impact of influenza is growing and influenza has become an important issue on the public-health agenda in many countries.15,16 However, the use of available influenza vaccines is still far from optimal.
    Go to context

  • Table 17 presents the recommendations for influenza vaccination adopted in most countries.
    Go to context

  • As a result, many clinical studies have now produced consistent data showing the clear-cut benefits of influenza vaccination.12,13,33,35,40 Since the elderly comprise by far the largest target population for flu vaccination, the majority of studies evaluating the benefits of vaccination have been conducted among people in this age group; these will be discussed in more detail below.
    Go to context

  • In evaluating the outcome of influenza vaccination, a distinction is often made between vaccine efficacy per se and the clinical effectiveness of vaccination.12,13 Vaccine efficacy is defined as the reduction in the rate of laboratory-confirmed influenza among vaccinated compared to non-vaccinated individuals.
    Go to context

  • It is defined as the reduction of clinically relevant, but not necessarily influenza-specific, disease in a “real-life” situation, including all influenza-like illness (ILI), hospitalizations due to pneumonia from all causes or death from all causes.12,13,40 As this parameter includes – by definition – disease that is not caused by the influenza virus, clinical effectiveness of vaccination is generally estimated to be lower than the actual vaccine efficacy, as illustrated by the hypothetical example presented in Figure 28.13 Therefore, clinical effectiveness should not be confused for vaccine efficacy, as this may result in a substantial underestimation of the actual performance of the vaccine.
    Go to context

  • It is defined as the reduction of clinically relevant, but not necessarily influenza-specific, disease in a “real-life” situation, including all influenza-like illness (ILI), hospitalizations due to pneumonia from all causes or death from all causes.12,13,40 As this parameter includes – by definition – disease that is not caused by the influenza virus, clinical effectiveness of vaccination is generally estimated to be lower than the actual vaccine efficacy, as illustrated by the hypothetical example presented in Figure 28.13 Therefore, clinical effectiveness should not be confused for vaccine efficacy, as this may result in a substantial underestimation of the actual performance of the vaccine.
    Go to context

  • Numerous studies have convincingly demonstrated the clinical benefits of influenza vaccination in the elderly.12,13,40,48,49 For example, in a large study in the USA, spanning two influenza seasons (1998–2000) and involving 300,000 community-dwelling elderly people (≥65 years), influenza vaccination was performed in 55.5–59.7% of the population.
    Go to context

  • Economic evaluations, conducted in many different countries, have indicated that vaccination of senior citizens against influenza is always cost-effective and frequently cost-saving.12,13 For example, in a 6-year study carried out in Minnesota, USA, influenza vaccination of nursing-home residents was associated with an average net saving of $73 per person as a result of reductions in direct medical costs.12 Vaccination appears to be cost-effective or even cost-saving for both healthy senior citizens and high-risk elderly with underlying chronic medical conditions.
    Go to context


  • Go to context

  • This is why there is an increasing awareness of the potential benefits of vaccination of working adults.12,13 Several prospective clinical studies have demonstrated the efficacy of inactivated influenza vaccines among healthy younger adults.
    Go to context

  • As demonstrated by a number of studies, conducted in different countries, vaccination significantly reduces illness, absenteeism and influenza-related costs for healthy adults in the work place.12,13 Indeed, vaccination reduces upper respiratory tract and influenza-like illnesses from all causes by approximately 30%, related physician visits by >40% and work loss by >35% (Table 20).60,61 Accordingly, cost–benefit analyses, based on clinical trials or on modelling, have shown that vaccination of healthy working adults is cost-effective and in many cases cost-saving, provided that indirect costs associated with work absenteeism (see Chapter 6) are explicitly taken into account.62 For example, trials conducted in the USA have shown that – with an average cost for vaccine production and administration of $20 – the net saving would be $23 per person vaccinated.63 In another study comparing 131 vaccinated employees from six textile plants in North Carolina, USA, with 131 age- and gender-matched non-vaccinated controls from different plants, the “cost per saved lost work day” was $22.36, resulting in an overall saving of $2.58 per dollar invested in the vaccination programme.64 Other, model-based, studies also indicate that vaccinating working adults would be cost-saving.12 While recent international guidelines for pharmacoeconomic analyses do explicitly recommend the inclusion of production gains and losses,62 also when such indirect costs are not taken into account, vaccination of adults below the age of 65 turns out to be highly cost-effective.
    Go to context

KL Nichol. Efficacy/clinical effectiveness of inactivated influenza virus vaccines in adults. KG Nicholson, RG Webster, AJ Hay (Eds.) Textbook of Influenza (Blackwell Science, 1998) (358 - 372) 1998
27

References in context

  • This is particularly relevant because of the relatively low vaccine coverage rates in patients at risk who are younger than 65 years of age.27–29 Currently, more countries are considering lowering the age limit for vaccination recommendation.
    Go to context

MW Kroneman, GA van Essen, MA Tacken, et al.. Does a population survey provide reliable influenza vaccine uptake rates among high-risk groups? A case-study of The Netherlands. Crossref. Vaccine 22 (2004) (2163 - 2170) 2004
28

References in context

  • This is particularly relevant because of the relatively low vaccine coverage rates in patients at risk who are younger than 65 years of age.27–29 Currently, more countries are considering lowering the age limit for vaccination recommendation.
    Go to context

  • However, despite the increased vaccine use, recent surveys in Europe show that the coverage rates in target populations are still far from the WHO-recommended 75% in 2010.29,36 The current coverage rates range from 18% (Poland) to 67% (Spain) for the elderly and from 3% to 40% for various risk groups in younger populations.28,29,37 In the USA, only 35% of adults between the ages of 18 and 64 years who are at risk for serious complications due to influenza were being vaccinated in 2003.38 The implication of these findings is that many elderly and at-risk patients are not receiving the best possible protective treatment to prevent influenza or minimize the consequences of an influenza infection.
    Go to context

M Kroneman, GA van Essen, W John Paget. Influenza vaccination coverage and reasons to refrain among high-risk persons in four European countries. Crossref. Vaccine 24 (2006) (622 - 628) 2006
29

References in context

  • This is particularly relevant because of the relatively low vaccine coverage rates in patients at risk who are younger than 65 years of age.27–29 Currently, more countries are considering lowering the age limit for vaccination recommendation.
    Go to context

  • However, despite the increased vaccine use, recent surveys in Europe show that the coverage rates in target populations are still far from the WHO-recommended 75% in 2010.29,36 The current coverage rates range from 18% (Poland) to 67% (Spain) for the elderly and from 3% to 40% for various risk groups in younger populations.28,29,37 In the USA, only 35% of adults between the ages of 18 and 64 years who are at risk for serious complications due to influenza were being vaccinated in 2003.38 The implication of these findings is that many elderly and at-risk patients are not receiving the best possible protective treatment to prevent influenza or minimize the consequences of an influenza infection.
    Go to context

  • However, despite the increased vaccine use, recent surveys in Europe show that the coverage rates in target populations are still far from the WHO-recommended 75% in 2010.29,36 The current coverage rates range from 18% (Poland) to 67% (Spain) for the elderly and from 3% to 40% for various risk groups in younger populations.28,29,37 In the USA, only 35% of adults between the ages of 18 and 64 years who are at risk for serious complications due to influenza were being vaccinated in 2003.38 The implication of these findings is that many elderly and at-risk patients are not receiving the best possible protective treatment to prevent influenza or minimize the consequences of an influenza infection.
    Go to context

  • Therefore, primary-care physicians and other health-care workers play a major role in implementing influenza vaccination programmes,29 as discussed in more detail in the last paragraph of this chapter.
    Go to context

  • National health authorities of eight different European countries have recently discussed possible ways to reach the WHO vaccine coverage rate objectives for 2010.29 Health-care professionals play the single most important role in making this happen.
    Go to context

TD Szucs, D Muller. Influenza vaccination coverage rates in five European countries – a population-based cross-sectional analysis of two consecutive influenza seasons. Crossref. Vaccine 23 (2005) (5055 - 5063) 2005
30

References in context

  • Table 17 presents the recommendations for influenza vaccination adopted in most countries.
    Go to context

  • As demonstrated by a number of studies, conducted in different countries, vaccination significantly reduces illness, absenteeism and influenza-related costs for healthy adults in the work place.12,13 Indeed, vaccination reduces upper respiratory tract and influenza-like illnesses from all causes by approximately 30%, related physician visits by >40% and work loss by >35% (Table 20).60,61 Accordingly, cost–benefit analyses, based on clinical trials or on modelling, have shown that vaccination of healthy working adults is cost-effective and in many cases cost-saving, provided that indirect costs associated with work absenteeism (see Chapter 6) are explicitly taken into account.62 For example, trials conducted in the USA have shown that – with an average cost for vaccine production and administration of $20 – the net saving would be $23 per person vaccinated.63 In another study comparing 131 vaccinated employees from six textile plants in North Carolina, USA, with 131 age- and gender-matched non-vaccinated controls from different plants, the “cost per saved lost work day” was $22.36, resulting in an overall saving of $2.58 per dollar invested in the vaccination programme.64 Other, model-based, studies also indicate that vaccinating working adults would be cost-saving.12 While recent international guidelines for pharmacoeconomic analyses do explicitly recommend the inclusion of production gains and losses,62 also when such indirect costs are not taken into account, vaccination of adults below the age of 65 turns out to be highly cost-effective.
    Go to context

J Chancellor. Lowering the age threshold for routine influenza vaccination to 50 years: cost-effectiveness analysis for European countries. Vaccine (2006) in press. 2006
31

References in context

  • Table 17 presents the recommendations for influenza vaccination adopted in most countries.
    Go to context

  • Initial trials, conducted among military recruits several decades ago,57 showed that the vaccine was 70–90% efficacious in preventing laboratory-confirmed influenza, provided there was a good antigenic match between vaccine and circulating virus.58 A review of more recent clinical studies shows that the efficacy of inactivated influenza vaccines varied from 65% for all influenza seasons to 72% for those seasons where there was a good match between vaccine and circulating virus.31 Additional studies have reported vaccine efficacies in terms of prevention of confirmed influenza in the range of 80–90% in cases where there was a good match.59,60 Clearly, current inactivated influenza vaccines attain very high efficacy values among healthy younger adults (Table 20).
    Go to context

  • As demonstrated by a number of studies, conducted in different countries, vaccination significantly reduces illness, absenteeism and influenza-related costs for healthy adults in the work place.12,13 Indeed, vaccination reduces upper respiratory tract and influenza-like illnesses from all causes by approximately 30%, related physician visits by >40% and work loss by >35% (Table 20).60,61 Accordingly, cost–benefit analyses, based on clinical trials or on modelling, have shown that vaccination of healthy working adults is cost-effective and in many cases cost-saving, provided that indirect costs associated with work absenteeism (see Chapter 6) are explicitly taken into account.62 For example, trials conducted in the USA have shown that – with an average cost for vaccine production and administration of $20 – the net saving would be $23 per person vaccinated.63 In another study comparing 131 vaccinated employees from six textile plants in North Carolina, USA, with 131 age- and gender-matched non-vaccinated controls from different plants, the “cost per saved lost work day” was $22.36, resulting in an overall saving of $2.58 per dollar invested in the vaccination programme.64 Other, model-based, studies also indicate that vaccinating working adults would be cost-saving.12 While recent international guidelines for pharmacoeconomic analyses do explicitly recommend the inclusion of production gains and losses,62 also when such indirect costs are not taken into account, vaccination of adults below the age of 65 turns out to be highly cost-effective.
    Go to context

DA Turner, AJ Wailoo, NJ Cooper, et al.. The cost-effectiveness of influenza vaccination of healthy adults 50–64 years of age. Crossref. Vaccine 24 (2006) (1035 - 1043) 2006
32

References in context

  • Table 17 presents the recommendations for influenza vaccination adopted in most countries.
    Go to context

Centers for Disease Control and Prevention. Influenza vaccination in pregnancy: practices among obstetrician-gynecologists – United States, 2003–04 influenza season. MMWR 54 (2005) (1050 - 1052) (www.cdc.gov/mmwr/preview/mmwrhtml/mm5441a4.htm) 2005
33

References in context

  • Table 17 presents the recommendations for influenza vaccination adopted in most countries.
    Go to context

  • As a result, many clinical studies have now produced consistent data showing the clear-cut benefits of influenza vaccination.12,13,33,35,40 Since the elderly comprise by far the largest target population for flu vaccination, the majority of studies evaluating the benefits of vaccination have been conducted among people in this age group; these will be discussed in more detail below.
    Go to context


  • Go to context

  • However, there is increasing epidemiological evidence of the burden of disease in children33 and of vaccination effectiveness.33,35,66 In addition to the direct benefits for the vaccinated children, a vaccination programme for children may also have the potential for reducing the impact of influenza epidemics, because children play an important role in the spread of influenza infections in communities.66,67 In addition, influenza among children is a significant cause of parental work loss.
    Go to context

  • However, there is increasing epidemiological evidence of the burden of disease in children33 and of vaccination effectiveness.33,35,66 In addition to the direct benefits for the vaccinated children, a vaccination programme for children may also have the potential for reducing the impact of influenza epidemics, because children play an important role in the spread of influenza infections in communities.66,67 In addition, influenza among children is a significant cause of parental work loss.
    Go to context

  • However, there is increasing epidemiological evidence of the burden of disease in children33 and of vaccination effectiveness.33,35,66 In addition to the direct benefits for the vaccinated children, a vaccination programme for children may also have the potential for reducing the impact of influenza epidemics, because children play an important role in the spread of influenza infections in communities.66,67 In addition, influenza among children is a significant cause of parental work loss.
    Go to context

T Heikkinen, R Booy, M Campins, et al.. Should healthy children be vaccinated against influenza? A consensus report of the Summits of Independent European Vaccination Experts. Eur J Pediatr 21 (2005) (1 - 6) 2005
34

References in context

  • Table 17 presents the recommendations for influenza vaccination adopted in most countries.
    Go to context

  • Because of the non-specific criteria of influenza-like illness (ILI), the outcome of clinical effectiveness studies depends on the used case definition in the particular study.
    Go to context

T Heikkinen, O Ruuskanen. Influenza vaccines in healthy children (letter to the editor). Crossref. Lancet 365 (2005) (2086 - 2087) 2005
35

References in context

  • Table 17 presents the recommendations for influenza vaccination adopted in most countries.
    Go to context

  • As a result, many clinical studies have now produced consistent data showing the clear-cut benefits of influenza vaccination.12,13,33,35,40 Since the elderly comprise by far the largest target population for flu vaccination, the majority of studies evaluating the benefits of vaccination have been conducted among people in this age group; these will be discussed in more detail below.
    Go to context

  • However, there is increasing epidemiological evidence of the burden of disease in children33 and of vaccination effectiveness.33,35,66 In addition to the direct benefits for the vaccinated children, a vaccination programme for children may also have the potential for reducing the impact of influenza epidemics, because children play an important role in the spread of influenza infections in communities.66,67 In addition, influenza among children is a significant cause of parental work loss.
    Go to context

  • A similar observation has been made in a recent study in Russia.35 School children in some regions in the Moscow area were systematically vaccinated with a classical inactivated subunit vaccine, whereas in control areas no such vaccination strategy was installed.
    Go to context

  • A similar observation has been made in a recent study in Russia.35 School children in some regions in the Moscow area were systematically vaccinated with a classical inactivated subunit vaccine, whereas in control areas no such vaccination strategy was installed.
    Go to context

YZ Ghendon, AN Kaira, GA Elshina. The effect of mass influenza immunization in children on the morbidity of the unvaccinated elderly. Epidemiol Infect 134 (2006) (71 - 78) 2006
36

References in context

  • However, despite the increased vaccine use, recent surveys in Europe show that the coverage rates in target populations are still far from the WHO-recommended 75% in 2010.29,36 The current coverage rates range from 18% (Poland) to 67% (Spain) for the elderly and from 3% to 40% for various risk groups in younger populations.28,29,37 In the USA, only 35% of adults between the ages of 18 and 64 years who are at risk for serious complications due to influenza were being vaccinated in 2003.38 The implication of these findings is that many elderly and at-risk patients are not receiving the best possible protective treatment to prevent influenza or minimize the consequences of an influenza infection.
    Go to context

  • However, despite the increased vaccine use, recent surveys in Europe show that the coverage rates in target populations are still far from the WHO-recommended 75% in 2010.29,36 The current coverage rates range from 18% (Poland) to 67% (Spain) for the elderly and from 3% to 40% for various risk groups in younger populations.28,29,37 In the USA, only 35% of adults between the ages of 18 and 64 years who are at risk for serious complications due to influenza were being vaccinated in 2003.38 The implication of these findings is that many elderly and at-risk patients are not receiving the best possible protective treatment to prevent influenza or minimize the consequences of an influenza infection.
    Go to context


  • Go to context

  • As indicated in Chapter 3 and further described in Chapter 9, there is a societal urgency to achieve the WHO objectives,36 because this will not only ameliorate the annual burden of influenza but also contribute to a better level of pandemic preparedness.
    Go to context

  • As indicated in Chapter 3 and further described in Chapter 9, there is a societal urgency to achieve the WHO objectives,36 because this will not only ameliorate the annual burden of influenza but also contribute to a better level of pandemic preparedness.
    Go to context

Resolution WHA56.19. Prevention and control of influenza pandemics and annual epidemics (Fifty-Sixth World Health Assembly, Geneva, 19–28 May 2003) (www.who.int/gb/ebwha/pdf_files/WHA56/ea56r19.pdf) 1928 May 2003
37

References in context

  • However, despite the increased vaccine use, recent surveys in Europe show that the coverage rates in target populations are still far from the WHO-recommended 75% in 2010.29,36 The current coverage rates range from 18% (Poland) to 67% (Spain) for the elderly and from 3% to 40% for various risk groups in younger populations.28,29,37 In the USA, only 35% of adults between the ages of 18 and 64 years who are at risk for serious complications due to influenza were being vaccinated in 2003.38 The implication of these findings is that many elderly and at-risk patients are not receiving the best possible protective treatment to prevent influenza or minimize the consequences of an influenza infection.
    Go to context

  • The value of immunization against influenza is sometimes being questioned, as outbreaks of flu continue despite increased influenza vaccination coverage.39 Therefore, there has been a strong demand for sound scientific data on the effects of influenza vaccination.
    Go to context

SA Smith, GA Poland. The use of influenza and pneumococcal vaccines in people with diabetes (technical review). Crossref. Diabetes Care 23 (2000) (95 - 108) 2000
38

References in context

  • However, despite the increased vaccine use, recent surveys in Europe show that the coverage rates in target populations are still far from the WHO-recommended 75% in 2010.29,36 The current coverage rates range from 18% (Poland) to 67% (Spain) for the elderly and from 3% to 40% for various risk groups in younger populations.28,29,37 In the USA, only 35% of adults between the ages of 18 and 64 years who are at risk for serious complications due to influenza were being vaccinated in 2003.38 The implication of these findings is that many elderly and at-risk patients are not receiving the best possible protective treatment to prevent influenza or minimize the consequences of an influenza infection.
    Go to context

Centers for Disease Control and Prevention. Influenza vaccination levels among person aged ≥65 years and among persons aged 18–64 years with high-risk conditions – United States, 2003. MMWR 54 (2005) (1045 - 1049) (www.cdc.gov/mmwr/preview/mmwrhtml/mm5441a3.htm) 2005

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