«Department of Communicable Disease Surveillance and Response WHO Global Influenza Programme WHO Guidelines on the Use of Vaccines and Antivirals ...»
WHO Guidelines on the Use
of Vaccines and Antivirals
during Influenza Pandemics
Department of Communicable Disease
Surveillance and Response
WHO Global Influenza Programme
WHO Guidelines on the Use
of Vaccines and Antivirals
during Influenza Pandemics
World Health Organization
Department of Communicable Disease
Surveillance and Response
© World Health Organization 2004
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WHO/CDS/CSR/RMD/2004.8 WHO Guidelines on the Use of Vaccines and Antivirals during Influenza Pandemics
3. Guidelines for the use of vaccines and antivirals
3.1 Establishing goals and priorities
3.2 Guidelines on vaccine use during a pandemic
3.2.1 General considerations
3.2.2 Establishing priority groups
Essential service providers, including health care workers
Groups at high risk of death and severe complications requiring hospitalization
Persons without risk factors for complications
3.3 Guidelines for antiviral use during a pandemic
3.3.1 General considerations
3.3.2 Options for antiviral use
3.3.3 Establishing priority groups
Essential service providers, including health care workers (prophylaxis or treatment).................. 8 Groups at high risk of death and severe complications requiring hospitalization (prophylaxis or treatment)
Persons without known risk factors for complications from influenza (treatment)
4.1 Recommendations for establishing goals
4.2.1 Recommendations for national authorities and vaccine manufacturers
4.2.2 Recommendations for international collaboration
4.2.3 Recommendations for research
4.3.1 Recommendations for national authorities
4.3.2 Recommendations for research
Annex 1 - Pandemic Influenza Annex 2 - List of participants Annex 3 - Global Agenda on Influenza Surveillance and Control Annex 4 - Considerations for the Use of Vaccines during an Influenza pandemic Annex 5 - Considerations for the Use of Antivirals during an Influenza pandemic –1– WHO Guidelines on the Use of Vaccines and Antivirals during Influenza Pandemics WHO/CDS/CSR/RMD/2004.8
1. Introduction Influenza pandemics are sudden and unpredictable yet inevitable events. They have caused several global health emergencies during the last century. The first and most severe of these is estimated to have resulted in more than 40-50 million deaths worldwide1. Experts anticipate that the next pandemic, whenever it happens, will be associated with a high death toll and a high degree of illness requiring hospitalization, thus producing a considerable strain on health care resources. Pandemics are global by their very nature, and few countries are likely to be spared. In developing countries, where health care resources are already strained and the general population is frequently weakened by poor health and nutritional status, the impact is likely to be greatest (Annex 1).
Conditions surrounding the 1997 Hong Kong outbreak of “chicken influenza” highlight the need for advance planning to ensure an adequate response to a health emergency that is certain to be unpredictable, complex, rapidly evolving and accompanied by considerable public alarm. Once a pandemic begins it will be too late to accomplish the many key activities required to minimize the impact. Therefore, planning and implementation of preparatory activities must start well in advance.
Planning for pandemics will also enhance the capacity to respond to other large-scale health emergencies, including bioterrorist threats, that require mass access to prophylactic and therapeutic interventions and strong national plans which include a risk communication component to help calm public fears. The impact of pandemic influenza is likely to be far greater, by orders of magnitude, than most bioterrorism scenarios. Unlike most other health emergencies, pandemics occur in several waves and last one to two years. Response efforts will, therefore, need to be sustained for a prolonged period.
In addition, preparation for an influenza pandemic will enhance the response to influenza epidemics, which occur each year and are thought to kill every year from 500 000 to 1 million people worldwide.
Investment in pandemic preparedness thus has direct and immediate utility as a measure for reducing the impact of a certain and recurring event.
Influenza vaccines and antiviral drugs for influenza are essential components of a comprehensive pandemic response, which also includes planning for antibiotic supplies and other health care resources. However, the current reality is that most countries have no or very limited supplies. Such a situation would force national authorities to make difficult decisions concerning which citizens should receive first call on limited vaccines and drugs.
This document provides guidance to health policy-makers and national authorities on planning principles and options for the prioritization of vaccine and antiviral use during an influenza pandemic.
It includes recommendations on actions that can improve future supply for the many countries that currently have no national vaccine or antiviral production.
The document was drafted during a WHO Consultation on Guidelines for the Use of Vaccines and Antivirals during Influenza Pandemics, held from 2-4 October 2002 in Geneva, Switzerland.
Participants are listed in Annex 2. The document represents a contribution of the WHO Global Influenza Programme to the implementation of the Global Agenda on Influenza, reproduced in Annex 3.
2. Background Influenza vaccines have been available for over 60 years. Extensive experience during this long period has demonstrated their safety and efficacy. In populations at risk of severe complications, vaccination is known to reduce hospital admissions and deaths. Vaccination is thus the cornerstone of influenza prevention. As influenza viruses are constantly evolving, vaccine is produced each year with a composition based on the most relevant strains of virus identified through a global surveillance system.
Stockpiling of vaccine in preparation for a pandemic is not an option, as vaccine composition depends on the responsible virus and must await its appearance and identification at the start of the pandemic.
Vaccine will thus be in limited supply during the first part of the pandemic, and may not be available at all in some parts of the world.
The influenza antivirals currently in use will likely be effective in the prophylaxis and therapy of illness caused by a new pandemic virus. However, supplies would quickly be exhausted in the first part of the pandemic, when vaccine is not yet available and demand for an alternative control tool would be greatest. Advance stockpiling of the drugs for special purposes or special populations is one solution.
As the drugs are relatively stable, stockpiling is feasible; however, for most countries, cost will be an issue. Also, differences do exist between the M2 inhibitors, such as amantadine, and the neuraminidases, such as oseltamivir, requiring identification of their specific roles in a pandemic.
Because of these factors, countries will need to consider the potential for complementary use of vaccines and antivirals in planning for various phases of a pandemic. Vaccine will remain the primary means of influenza prevention once available, though antivirals will have a role for use in special situations.
Countries will be able to address pandemic requirements only if they plan for supplies of vaccines and antivirals now. Although vaccines and antivirals are a key part of a pandemic response strategy, the current market-based system has limited or no surge capacity to respond to sudden increases in demand. Manufacturers require regular estimates of demand on which to base production plans.
However, there are currently no estimates on the global use and demand for influenza vaccine and antivirals. In addition, vaccine distribution systems are often fragmented and may not be readily adapted to respond to a single overall national plan. Issues of liability also require resolution in advance of the next pandemic.
3. Guidelines for the use of vaccines and antivirals The response to the next influenza pandemic will need to address an inevitable shortage of vaccines and antivirals. Thus, each country should decide in advance which groups will have first call on scarce supplies. When establishing goals and setting priorities, policy-makers need to keep in mind the several years needed to construct new production facilities and significantly increase production capacity. Budgetary constraints may extend the time required to stockpile an adequate supply of antivirals to several years. Setting goals related to influenza pandemic preparedness will provide some of the data and incentives needed to increase production or to plan stockpiles. The need for setting goals and establishing priorities extends beyond the borders of any individual country. Estimates of global demand for vaccines and antivirals depend on national estimates fixed in line with the priorities set by individual countries. Priority setting at the national level is thus the first step towards global preparedness for a global event.
Setting goals and priorities for a pandemic is a process that will provide significant health benefits every year. A pandemic influenza planning process will identify problems with the current supply, distribution and use of vaccines and antivirals. Implementing plans to reduce the magnitude of these problems will enhance the availability of vaccines and antivirals for inter-pandemic periods.
Investment in pandemic preparedness thus brings an annual return. Setting goals in a formal, rational, measured process also demonstrates the competence and forward-thinking of leaders and policymakers as custodians of public health.
The following section provides guidelines and recommendations for national health authorities and policy-makers on the process of setting goals and prioritizing the use of available vaccines and antivirals.
3.1 Establishing goals and priorities Setting goals and choosing priorities will require the consideration of logistic, ethical, moral, cultural, legal, and other issues that surround decisions to allocate scarce resources. It is therefore essential that national health authorities work in close collaboration with other public and private sector groups that have roles and interests in protecting public health.
Countries should consider establishing a technical advisory committee with broad representation. The committee should advise policy-makers on goals and priorities, and on ways to improve the supply of vaccines and antivirals2.
The technical committee should first list all goals that should ideally be achieved with available
resources. Examples include:
· limiting economic losses It is useful to explicitly state the units for measuring success. For example, the goal of reducing morbidity could be stated as ‘reduction in morbidity as measured by years of healthy life lost’ or ‘disability-adjusted life-years lost.’ When setting goals, it may also be useful to identify population subsets, such as medical personnel, emergency responders, and leaders, who require priority protection because of their roles during the pandemic response. Definition of these subsets should be flexible, allowing for changes in critical personnel based on likely exposure scenarios. However, when identifying such subsets, it is important to think through the potential practical (financial, political, ethical and health) consequences. For example, if a group is targeted to receive priority prophylaxis or treatment, will their family members also be given first priority? When setting goals, measures considered equitable and essential for each country need to be discussed.
As supplies of vaccines and antivirals are likely to be scarce, meeting all goals simultaneously will be difficult. Planners and policy-makers should therefore prioritize goals. This will facilitate the distribution of supplies in an optimal manner. The strategy for meeting priority goals will also be heavily influenced as the pandemic unfolds and its epidemiology, in terms of who falls ill and who dies, becomes apparent.
In order to define and prioritize goals, advisors and policy-makers will need estimates of the impact of a pandemic, including the number of persons who may become ill (by age and risk group) and the societal and economic consequences of their illness (medical resources used for treatments, costs of treatments, losses in productivity and social functions). Such estimates of impact are important for
allocating resources for planning and responding to a pandemic. Thus there is a need to collect data from which estimates to can be made, for example, the average cost of a case of influenza (including value of lost productivity) and the cost of distributing and administering vaccines and antivirals. To fully appreciate the limitations of current supply, policy-makers also need to know who currently gets vaccines and how they receive them.