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Introduction

Prevention and control

Vaccination

Vaccination remains the cornerstone of influenza prevention (see Chapter 8). Inactivated influenza vaccines have been in use for the past 60 years ( Figure 3 ). These vaccines have an excellent safety record and have proven to be efficacious in preventing influenza and reducing complications and deaths. The WHO recommends annual vaccination of people in at-risk groups. 8, x World Health Organization. Influenza vaccines. Wkly Epidemiol Rec 75 (2000) (281 - 288) (www.who.int/docstore/wer/pdf/2000/wer7535.pdf) 9 x World Health Organization. Influenza vaccines. Wkly Epidemiol Rec 77 (2002) (230 - 239) (www.who.int/docstore/wer/pdf/2002/wer7728.pdf) The primary target groups for annual vaccination include the elderly, nursing-home residents, patients with chronic respiratory or cardiovascular disease, diabetes or renal dysfunction, as well as immunocompromised individuals. In addition, it is also recommended that health-care workers and family members of people in high-risk groups be vaccinated.

Figure 3 Influenza vaccination in the 1950s. source: Photograph courtesy of Solvay Pharmaceuticals, Weesp, the Netherlands.

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References in context

  • Inactivated influenza vaccines have been in use for the past 60 years (Figure 3).
    Go to context

The clinical effectiveness and cost-effectiveness of inactivated influenza vaccines have been clearly demonstrated. 34 x KL Nichol. The efficacy, effectiveness and cost-effectiveness of inactivated influenza virus vaccines. Vaccine 21 (2003) (1769 - 1775) Crossref. For example, vaccination of community-dwelling senior citizens reduces hospitalization rates for pneumonia or other respiratory conditions by >30% and death from all causes by 50%. For nursing-home residents the benefits of influenza vaccination are even more striking, with reductions of hospitalization rates or death from all causes of 48% and 68%, respectively (see Chapter 8).

However, despite the established effectiveness of immunization, the national and international response to influenza prevention measures is often inadequate (see Chapter 8). In many countries, the established benefits of vaccination have not been translated into effective immunization programmes. Only 50 countries have policies for influenza immunization and often only 10–20% of people in high-risk groups, particularly those below the age of 65, are protected. 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) 29 x Influenza: Report by the WHO Secretariat for 111th session of the WHO Executive Board, January 2003. Document EB111/10 (WHO, November 2002) (www.who.int/gb/ebwha/pdf_files/EB111/eeb11110.pdf) While we do have the means to prevent the serious consequences of influenza, the implementation of preventive measures is still suboptimal, and as a consequence, currently many at-risk individuals remain unprotected and vulnerable to infection and death. 11, x A Palache. Influenza vaccines. A reappraisal of their use. Drugs 54 (1997) (841 - 856) Crossref. 29 x Influenza: Report by the WHO Secretariat for 111th session of the WHO Executive Board, January 2003. Document EB111/10 (WHO, November 2002) (www.who.int/gb/ebwha/pdf_files/EB111/eeb11110.pdf)

“The relatively low uptake of influenza vaccines in most industrialized countries implies that significant proportions of the groups at risk of complications from influenza are not vaccinated. WHO strongly emphasizes the importance of raising the public consciousness of influenza and its complications as well as of the beneficial effects of influenza vaccination.”World Health Organization ( Ref. 9 x World Health Organization. Influenza vaccines. Wkly Epidemiol Rec 77 (2002) (230 - 239) (www.who.int/docstore/wer/pdf/2002/wer7728.pdf) ; Appendix 3)

How can vaccine uptake be further encouraged?

As indicated above, the WHO recommends annual immunization of at-risk persons as the best and most cost-effective strategy for reducing influenza-related morbidity and mortality.8,9,29 However, there is often a gap between policy, on the one hand, and practice and uptake by the population, on the other, especially when interventions depend on people to change their behaviour to lower disease risk. Public-health policy is most effectively translated into improved health outcomes when social and individual contexts are clearly understood and relevant communities are engaged in the process.

Health-care workers, because of their direct relationship with the patient, are in an optimal position to promote preventive measures and explain the facts about influenza, its complications and the safety and efficacy of influenza vaccination. Accordingly, the WHO encourages initiatives to raise the awareness, particularly among health-care professionals, about the impact of influenza and the benefits of influenza vaccination.9 On the basis of the available evidence, offering vaccination to at-risk patients is no less than an ethical obligation.11 Indeed, by ensuring that all people in target groups are vaccinated, according to the recommendations of the WHO8,9 and many national health authorities, the health-care worker can make a significant contribution to public health. If, ultimately, health-care workers would decide to vaccinate the majority of their at-risk patients, this would go a long way towards ameliorating the burden of future influenza epidemics and pandemics.

Antivirals

While vaccination is the method of choice for influenza prophylaxis, under specific conditions where the individual has not been or cannot be vaccinated, or is not fully protected by vaccination, the use of antiviral drugs should be considered for treatment or prevention of influenza infection (see Chapter 7). In this regard, the physician needs to know whether influenza is circulating in the community and how to diagnose influenza illness for the purpose of appropriate prescription of influenza antiviral drugs.

Antiviral drugs approved for treament or prophylaxis of influenza include the M2 channel inhibitors amantidine and rimantidine, and the neuraminidase inhibitors zanamivir and oseltamivir. The application of these drugs to clinical practice may be limited by issues of efficacy with respect to the type of influenza virus (influenza A vs B), drug resistance, adverse effects and cost. In the case of the M2 ion channel blockers, these drugs are only effective against influenza A, the induction of drug resistance is well documented and side effects can be significant, especially in older people. While these issues have not been apparent with the more recent neuraminidase inhibitors, high cost may be prohibitive for broad use of these drugs, while for the inhaled zanamivir there is a caution against its use in cases of airway hypersensitivity. These issues not only limit the use of antivirals for individual treatment, but also present major challenges to their potential use in future pandemics (see Chapter 7).

Is the world prepared for the next pandemic?

Since the 1997 H5N1 avian flu outbreak in Hong Kong, the need for intensified measures to control future influenza pandemics has been widely recognized. In 2003, a resolution of the World Health Assembly urged member states to increase their efforts in the area of influenza prevention. 29 x Influenza: Report by the WHO Secretariat for 111th session of the WHO Executive Board, January 2003. Document EB111/10 (WHO, November 2002) (www.who.int/gb/ebwha/pdf_files/EB111/eeb11110.pdf) In November 2005, during a large international meeting with participation of the WHO, the World Bank, the UN co-ordinator for pandemic preparedness and delegates from over 100 countries, 35 x World Health Organization. Avian influenza and human pandemic influenza. Summary report of meeting held in Geneva. (www.who.int/mediacentre/events/2005/avian_influenza/summary_report_Nov_2005_meeting.pdf) (7–9 November 2005) there was broad consensus that the threat of a pandemic remains. While the mass culling of poultry in Hong Kong in 1997 ( Figure 4 ) may have averted a pandemic, in the meantime not only has the H5N1 virus reappeared, but it has now spread throughout many countries in Asia and parts of Europe, Africa and the Middle East, probably carried by infected migratory water fowl. During these ongoing H5N1 outbreaks, there have been 179 confirmed human infections (March 1, 2006), with a case-fatality rate of over 50%. 27 x World Health Organization. Cumulative number of confirmed human cases of avian influenza A/(H5N1) reported to WHO. (www.who.int/csr/disease/avian_influenza/country/en/index.html) Clearly, it is only a matter of time before another pandemic influenza virus will emerge. This will inevitably result in the death of millions of people unless preventive measures are adequately instituted.

Figure 4 Culling of chickens during the 1997 outbreak of H5N1 avian flu in Hong Kong. source: Copyright © Reuters/CORBIS.

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References in context

  • While the mass culling of poultry in Hong Kong in 1997 (Figure 4) may have averted a pandemic, in the meantime not only has the H5N1 virus reappeared, but it has now spread throughout many countries in Asia and parts of Europe, Africa and the Middle East, probably carried by infected migratory water fowl.
    Go to context

However, despite the imminent pandemic threat, most countries and the world at large are still not sufficiently prepared to contain a new global influenza outbreak. For example, in the current situation, no country will have vaccines at the start of the pandemic and production of significant quantities of vaccine will take many months after the first detection of the new pandemic virus 36 x CJ Luke, K Subbarao. Vaccines for pandemic influenza. Emerg Inf Dis 12 (2006) (66 - 72) Crossref. (see also Chapter 9). There are also concerns about the efficacy of antivirals for both treatment and prophylaxis in the setting of a pandemic, which may thwart antiviral stockpiling strategies 37 x A Monto. Vaccine and antiviral drugs in pandemic preparedness. Emerg Inf Dis 12 (2006) (55 - 60) Crossref. (see also Chapter 7). Therefore, there remains a need for more preparatory action.

Fortunately, many countries now do have pandemic preparedness plans in place which describe how these countries will deal with the emergency and what steps will be taken to contain a potential future pandemic as much as possible. The single most important aspect of further improved national as well as international pandemic preparedness involves the stimulation of annual influenza vaccine uptake among target groups (see Chapter 8) along with the development of more effective vaccine formulations including procedures to generate these vaccines as rapidly as possible once the pandemic emerges (see Chapter 9). The availability of more effective vaccines will permit individual countries and the global community at large to distribute the scarce quantities of vaccine antigen in an equitable fashion, such that not only the people in the wealthy countries, but also those in the Third World, will be protected as much as possible.

 
x

Figure 3 Influenza vaccination in the 1950s. source: Photograph courtesy of Solvay Pharmaceuticals, Weesp, the Netherlands.

f01-03-9780723434337

References in context

  • Inactivated influenza vaccines have been in use for the past 60 years (Figure 3).
    Go to context

Figure 4 Culling of chickens during the 1997 outbreak of H5N1 avian flu in Hong Kong. source: Copyright © Reuters/CORBIS.

f01-04-9780723434337

References in context

  • While the mass culling of poultry in Hong Kong in 1997 (Figure 4) may have averted a pandemic, in the meantime not only has the H5N1 virus reappeared, but it has now spread throughout many countries in Asia and parts of Europe, Africa and the Middle East, probably carried by infected migratory water fowl.
    Go to context

References

Label Authors Title Source Year
8

References in context

  • Accordingly, the World Health Organization (WHO) has issued guidelines for the implementation of influenza vaccination programmes in individual countries.8,9 As a result, many thousands of lives are saved worldwide each year.
    Go to context

  • The WHO recommends annual vaccination of people in at-risk groups.8,9 The primary target groups for annual vaccination include the elderly, nursing-home residents, patients with chronic respiratory or cardiovascular disease, diabetes or renal dysfunction, as well as immunocompromised individuals.
    Go to context

World Health Organization. Influenza vaccines. Wkly Epidemiol Rec 75 (2000) (281 - 288) (www.who.int/docstore/wer/pdf/2000/wer7535.pdf) 2000
9

References in context

  • Accordingly, the World Health Organization (WHO) has issued guidelines for the implementation of influenza vaccination programmes in individual countries.8,9 As a result, many thousands of lives are saved worldwide each year.
    Go to context

  • The WHO recommends annual vaccination of people in at-risk groups.8,9 The primary target groups for annual vaccination include the elderly, nursing-home residents, patients with chronic respiratory or cardiovascular disease, diabetes or renal dysfunction, as well as immunocompromised individuals.
    Go to context


  • Go to context

World Health Organization. Influenza vaccines. Wkly Epidemiol Rec 77 (2002) (230 - 239) (www.who.int/docstore/wer/pdf/2002/wer7728.pdf) 2002
10

References in context

  • Yet, in many places, implementation of vaccination programmes remains woefully deficient.10,11 This implies that significant numbers of people at risk of the complications of influenza remain vulnerable to infection and possibly death.
    Go to context

  • However, despite the established effectiveness of immunization, the national and international response to influenza prevention measures is often inadequate (see Chapter 8).
    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

  • Yet, in many places, implementation of vaccination programmes remains woefully deficient.10,11 This implies that significant numbers of people at risk of the complications of influenza remain vulnerable to infection and possibly death.
    Go to context

  • However, despite the established effectiveness of immunization, the national and international response to influenza prevention measures is often inadequate (see Chapter 8).
    Go to context

A Palache. Influenza vaccines. A reappraisal of their use. Crossref. Drugs 54 (1997) (841 - 856) 1997
27

References in context

  • Similarly, in 2003, an outbreak of fowl plague (H7N7 subtype) in the Netherlands resulted in the direct transmission of the virus to poultry workers and veterinarians, killing one person.22 Furthermore, as of the end of 2003, continuing renewed outbreaks of highly pathogenic H5N1 avian influenza in Asia, and more recently also in Europe, Africa and the Middle East, have resulted in an increasing number of human infections with a very high case-fatality rate,23–27 underscoring the disconcerting possibility that this virus may further adapt to the human host and thus cause a new deadly worldwide outbreak of influenza.
    Go to context

  • During these ongoing H5N1 outbreaks, there have been 179 confirmed human infections (March 1, 2006), with a case-fatality rate of over 50%.27 Clearly, it is only a matter of time before another pandemic influenza virus will emerge.
    Go to context

World Health Organization. Cumulative number of confirmed human cases of avian influenza A/(H5N1) reported to WHO. (www.who.int/csr/disease/avian_influenza/country/en/index.html)
29

References in context

  • Each year, influenza results in 3–5 million cases of severe illness and kills between 0.25 and 0.5 million people worldwide.7,29 The WHO estimates that there are currently 1 billion people worldwide who are at high risk of suffering or dying from influenza and its complications.29 Furthermore, as the elderly population increases, future influenza epidemics will be associated with ever-increasing hospitalization rates and excess mortality unless adequate prophylactic measures are taken.
    Go to context

  • Each year, influenza results in 3–5 million cases of severe illness and kills between 0.25 and 0.5 million people worldwide.7,29 The WHO estimates that there are currently 1 billion people worldwide who are at high risk of suffering or dying from influenza and its complications.29 Furthermore, as the elderly population increases, future influenza epidemics will be associated with ever-increasing hospitalization rates and excess mortality unless adequate prophylactic measures are taken.
    Go to context

  • However, despite the established effectiveness of immunization, the national and international response to influenza prevention measures is often inadequate (see Chapter 8).
    Go to context

  • However, despite the established effectiveness of immunization, the national and international response to influenza prevention measures is often inadequate (see Chapter 8).
    Go to context

  • In 2003, a resolution of the World Health Assembly urged member states to increase their efforts in the area of influenza prevention.29 In November 2005, during a large international meeting with participation of the WHO, the World Bank, the UN co-ordinator for pandemic preparedness and delegates from over 100 countries,35 there was broad consensus that the threat of a pandemic remains.
    Go to context

Influenza: Report by the WHO Secretariat for 111th session of the WHO Executive Board, January 2003. Document EB111/10 (WHO, November 2002) (www.who.int/gb/ebwha/pdf_files/EB111/eeb11110.pdf) November 2002
34

References in context

  • The clinical effectiveness and cost-effectiveness of inactivated influenza vaccines have been clearly demonstrated.34 For example, vaccination of community-dwelling senior citizens reduces hospitalization rates for pneumonia or other respiratory conditions by >30% and death from all causes by 50%.
    Go to context

KL Nichol. The efficacy, effectiveness and cost-effectiveness of inactivated influenza virus vaccines. Crossref. Vaccine 21 (2003) (1769 - 1775) 2003
35

References in context

  • In 2003, a resolution of the World Health Assembly urged member states to increase their efforts in the area of influenza prevention.29 In November 2005, during a large international meeting with participation of the WHO, the World Bank, the UN co-ordinator for pandemic preparedness and delegates from over 100 countries,35 there was broad consensus that the threat of a pandemic remains.
    Go to context

World Health Organization. Avian influenza and human pandemic influenza. Summary report of meeting held in Geneva. (www.who.int/mediacentre/events/2005/avian_influenza/summary_report_Nov_2005_meeting.pdf) (7–9 November 2005) 79 November 2005
36

References in context

  • For example, in the current situation, no country will have vaccines at the start of the pandemic and production of significant quantities of vaccine will take many months after the first detection of the new pandemic virus36 (see also Chapter 9).
    Go to context

CJ Luke, K Subbarao. Vaccines for pandemic influenza. Crossref. Emerg Inf Dis 12 (2006) (66 - 72) 2006
37

References in context

  • There are also concerns about the efficacy of antivirals for both treatment and prophylaxis in the setting of a pandemic, which may thwart antiviral stockpiling strategies37 (see also Chapter 7).
    Go to context

A Monto. Vaccine and antiviral drugs in pandemic preparedness. Crossref. Emerg Inf Dis 12 (2006) (55 - 60) 2006

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