Seasonal and Pandemic Influenza Vaccines
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Seasonal and Pandemic Influenza Vaccines : Vaccine Development and Production. Learning Objectives. Develop a basic understanding of how influenza vaccines are developed Be familiar with the major types of vaccines and methods of vaccine production

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Seasonal and Pandemic Influenza Vaccines:

Vaccine Development and Production


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Learning Objectives

  • Develop a basic understanding of how influenza vaccines are developed

  • Be familiar with the major types of vaccines and methods of vaccine production

  • Understand the importance of vaccine effectiveness and testing


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Outline

  • Overview of vaccine production

  • Seasonal influenza vaccination

  • Progress in developing vaccines for influenza viruses with pandemic potential



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Approaches to Influenza Vaccine Development

  • Subtype/strain-specific vaccines:

    • Induce immune response to hemagglutinin (HA) and neuraminidase (NA) viral proteins

    • Examples: Inactivated influenza virus vaccines, Live-attenuated vaccines, virus-like particles

  • Universal vaccines

    • Current area of investigation

    • Immunize with conserved proteins (for example: M2)

    • Broad-based immunity

    • Immune response against multiple subtypes


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Composition of Vaccines against Seasonal Influenza

  • Three strains selected to make a trivalent vaccine

    • Based on global viral surveillance

  • Selection decision precedes typical peak influenza season by 10-12 months

    • Northern Hemisphere strains selected in February

    • Southern hemisphere strains selected in September

  • “New vaccine” (one or more new strains) every year


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Types of Influenza Vaccines

Non-Replicating Vaccines

Replicating Vaccines

Antigens are replicated in host

Live attenuated vaccinesReplication restricted to the cooler upper airways

Microbial vector vaccines Bacterial vectors deliver DNA or RNA to host

DNA vaccines

Antigens are manufactured outside the host

  • InactivatedWhole or split virus

  • Recombinant proteinSingle protein, virus-like particles

  • Peptide


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Egg-based Manufacturing of Inactivated Influenza Vaccines

  • Must maintain flocks and viable eggs

  • Bacteria inherent on surface of eggs

  • Seed viruses must be adapted to eggs

  • Not set-up for high-level bio-containment

    Cannot use wild type highly pathogenic viruses

CDC/ Dr. Stan Foster


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Cell-based Manufacturing of Inactivated Influenza Vaccines

  • Storage in a working cell bank

  • Fermenter for growth of tissue cultures

  • Requirement for special supplements:

    • Carrier beads (to maximize cell growth surface area)

    • Protease or growth additives

  • Variable replication efficiency: wild type and “high growth” reassortants

  • Manufacturing with high biocontainment (BSL3) must be used for highly pathogenic strains



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Constraints with Current Seasonal Vaccines

  • Selection of strains difficult and time consuming

  • Annual, seasonal production

  • Technical process, specialized facilities

  • Lack of cross protection against antigenic variants

    • Long term protection uncertain

  • Relatively high cost

  • Annual vaccine administration is required


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Review Question 1

What type of manufacturing is most commonly used for influenza vaccines?

  • Egg-based

  • Cell-culture based

  • Reverse genetics

  • None of the above

    Answer: A. Currently available vaccines are manufactured using embryonated chicken eggs or egg-based manufacturing



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Antibody Response to Influenza Vaccination

  • Post-vaccination antibody correlates with protection

  • Peak antibody response 2 weeks after vaccination in people needing only one dose

  • Immunity wanes during the year

    • Lasts through the influenza season

    • Requires annual vaccination


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Determinants of Antibody Response to Influenza Vaccines

  • Age

    • Elderly and young children can have lower antibody response

  • Prior exposure to virus strains similar to those in vaccine (infection or vaccination)

  • Immune competence of person being vaccinated

  • Amount of antigen in vaccine

  • Type of vaccine

  • Presence of adjuvants


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Measuring Effectiveness of Seasonal Influenza Vaccine

  • Effectiveness varies by age group, risk group, and antigenic match

  • Different study methods make comparisons difficult

    • Observational studies: Easier to do but differences between vaccinated and unvaccinated persons can bias results

    • Randomized controlled trials: Reduce bias, but costly

  • Variety of outcomes can be measured that make comparisons between studies difficult

    • Less specific: Influenza-like illness (ILI)

    • More specific: Laboratory-confirmed influenza


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Effect of Co-circulation of Non-influenza Pathogens/Outcome Specificity on VE Estimate

Assuming 100 vaccinated and 100 unvaccinated in each set:

VE against influenza infection = 75% for both sets A and B,

VE against respiratory illness = 30% in set A and 15% in set B.


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Inactivated Seasonal Influenza Vaccine Effectiveness, by Age and Risk Group, when Vaccine Strains Match Circulating Strains

*Effectiveness lower when vaccine and circulating strains antigenically different. No vaccine effectiveness is sometimes observed when the prevalence of antigenically different strains in the community is high.

**Laboratory-confirmed influenza virus infection


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Global Distribution of Influenza Vaccines, 1994-2003 and Risk Group, when Vaccine Strains Match Circulating Strains

WHO Global Influenza Vaccine Distribution

http://www.who.int/csr/disease/influenza/vaccinedistribution/en/index.html


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Review Question 2 and Risk Group, when Vaccine Strains Match Circulating Strains

What are some of the individual or demographic attributes that affect vaccine effectiveness?

Answers:

  • Age

  • Immunocompetence

  • Amount of antigen present in vaccine

  • Vaccine type

  • Prior exposure to similar viral strains



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From Seasonal to Pandemic PotentialInfluenza Vaccine Production

  • Manufacturing facilities could shift production from seasonal vaccine to pandemic vaccines

  • Pandemic vaccines will not available at beginning of pandemic

    • Likely available within 4-6 months

  • Once available, there will be limited quantities initially

  • By this time there might be wide spread circulation of the pandemic strain


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Challenges to Development of Vaccines against Influenza A (H5N1)

  • Reduced immunogenicity compared to seasonal influenza vaccines, unless formulated with an adjuvant

  • Expense

    • Reduced yield in egg-based manufacturing processes

    • High antigen content

    • Proprietary adjuvants

  • Unknown cross protection against other clades

  • Predictive value of pre-clinical studies not established


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Priorities in Development of Pandemic Influenza Vaccines (H5N1)

  • Evaluation of dose-sparing strategies including use of adjuvants

  • Accelerated development of cell-culture based vaccines

  • Novel approaches to vaccine developmentIncluding vaccines that provide broad cross protection


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Potentially Pandemic Viral Strains under Study (H5N1)

  • H5N1

    • Multiple clades

  • H9N2

  • H7N7

  • H5N2

  • Swine-origin novel influenza A(H1N1)


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Immunogenicity of a Candidate Influenza A (H5N1) Vaccine (Sanofi)(A/Vietnam/1203/H5N1; Clade 1)

Treanor et al. N Eng J Med 2006;354:1343-51


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Influenza A (H5N1) Clade 1 Vaccine with Adjuvant (GlaxoSmithKline)

Inactivated influenza A (H5N1) clade 1 antigen and proprietary adjuvant

Design:

  • Placebo-controlled, ~400 healthy adults

  • 2 doses vaccine +/- adjuvant in doses from 3.8 to 30 micrograms

Results:

  • Adjuvanted formulations more immunogenic

  • Good antibody response (even at 3.8 micrograms)

  • Induced cross-reactive antibody responses against clade 2 strain

  • Met FDA requirements for licensure

Leroux-Roels et al. Lancet. 2007;370(9587):580-9.


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Candidate Influenza A (H5N1) Vaccines: Experience to Date (GlaxoSmithKline)

  • Inactivated subvirion vaccines: Immunogenicity suboptimal

    • High antigen content required (90 micrograms)

    • Require 2 doses

    • Few adverse events

  • Adjuvanted inactivated subvirion vaccines

    • Similar or better response compared to subvirion vaccines

      • Without adjuvant at doses as low as 3.8 micgrgrams

      • Need for 2 doses less certain

    • Antigen sparing (reduced antigen content needed)

    • Proprietary adjuvants have shown best antigen-sparing effects

    • Increased reactogenicity with adjuvants


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Target paradigm of an ideal (GlaxoSmithKline)

H5N1 pandemic vaccine

From: S Sambhara, CB Bridges,

GA Poland. Lancet 2007.


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Review Question 3 (GlaxoSmithKline)

Which technology that might be used to reduce the dose of antigen that is needed in a vaccine?

  • Cell-based technology

  • Adjuvants

  • Universal vaccine

  • None of the above

    Answer:

    b. Adjuvants


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Summary (GlaxoSmithKline)

  • Production using traditional methods will not meet global demand for a pandemic vaccine

  • H5N1 Vaccines produced using traditional seasonal influenza vaccine methods have relatively poor immunogenicity

    • Improved with use of adjuvants

  • Considerable progress with alternative vaccines


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Glossary (GlaxoSmithKline)

Antigen: Are proteins or polysaccharides that are parts of viral or bacterial structure and which prompt the immune system response

Adjuvant: A pharmacological or immunological agent added to a vaccine to modify (improve) the immune response to the vaccine, while having few if any direct affect when given by itself.

Biocontainment or Biosafety level (BSL): The isolation and containment of extremely infectious or hazardous materials in specialized and secure scientific facilities

Genetic engineering: the manipulation of genetic material, generally to produce a therapeutic or agricultural product either more quickly, or in greater quantities, than is seen in nature.


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Glossary (GlaxoSmithKline)

Embryonated: Egg containing an embryo, used to incubate viruses for vaccine study or production

Reassortant: Viruses that contain 2 or more pieces of genetic material from different viruses. Reassortant happens when two viruses mix within a cell (or lab environment).

Inactivated vaccine: a vaccine made from an infectious agent that has been inactivated or killed in some way.

Live, attenuated vaccine: Vaccine includes live pathogens that have lost their virulence but are still capable of inducing a protective immune response to the virulent forms of the pathogen.

Immunogenicity: Measure or ability of a substance (virus, drug, etc) to produce an immune system response


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Glossary (GlaxoSmithKline)

Clades: A biological group (for example, a viral species) that is classified according to genetic similarity

Subivirion: An incomplete virus or virus particle

Chemoprophylaxis: The use pharmaceutical or medical treatment to prevent disease or spread of infection

Virulence: The virulence of a microorganism (such as a bacterium or virus) is a measure of the severity of the disease it is capable of causing.

Pathogenicity: is the ability of an organism, a pathogen, to produce an infectious disease in another organism.


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Glossary (GlaxoSmithKline)

Trivalent influenza vaccine: synthetic vaccine consisting of three inactivated influenza viruses, two different influenza type A strains and one influenza type B strain. Trivalent influenza vaccine is formulated annually, based on influenza strains projected to be prevalent in the upcoming flu season. This agent may be formulated for injection or intranasal administration.

Candidate strains: strains of influenza that are used in vaccines that are still early in developmental stages

Antibody response: The immune system responds to antigens by producing antibodies. Antibodies are protein molecules that attach themselves to invading microorganisms and mark them for destruction or prevent them from infecting cells. Antibodies are antigen specific. That is antibodies produced in response to antigen exposure are specific to that antigen.


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Glossary (GlaxoSmithKline)

(S13) Egg-based (vaccine) manufacturing: Method of making influenza vaccines by inoculating live flu virus into fertilized chicken eggs, then purifying and inactivating the resulting egg-adapted virus. Vaccines created using this technique represent the majority of the currently licensed and marketed influenza vaccines worldwide

(S14) Cell-based (vaccine) manufacturing: Method of manufacturing influenza vaccine that is more rapid than egg-based manufacturing. The live flu virus is used to infect cells in culture. Once the viral infection has propagated through the cells, the live virus is harvested and inactivated for use in vaccines.


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Seasonal and Pandemic Influenza Vaccines: (GlaxoSmithKline)Programmatic Issues and Pandemic Preparedness


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Learning Objectives (GlaxoSmithKline)

  • Recognize the differences and challenges of seasonal vs. pandemic influenza vaccine development, manufacturing, and distribution


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Outline (GlaxoSmithKline)

  • Vaccine capacity

  • Vaccine access

  • Planning

  • WHO strategies


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Pre-pandemic: Vaccine Planning (GlaxoSmithKline)

  • Definition: Vaccines developed against influenza viruses that are currently circulating in animals and that have the potential to cause a pandemic in humans

  • Rationale: might provide priming or “limited protection” against pandemic strain

    • Goal: Reduce morbidity or mortality

    • Might not reduce number of viral infections

  • Problem: Which vaccine strains, and when should it be given?


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Pandemic Preparedness: (GlaxoSmithKline)Access to Vaccine

  • Global influenza vaccine production capacity is limited:

    • 300 million doses trivalent vaccine (900 million doses)

    • Monovalent vaccine (2 dose course) = 450 million courses

  • 65% of capacity is located in Europe

  • 85% of influenza production is by 3 companies

  • Countries with manufacturing capacity represent 12% of global population


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Pandemic Preparedness: Global Response (GlaxoSmithKline)

  • Increasing pressure from developing countries for access to influenza vaccine

  • When pandemic declared, potential for:

    • “Rationing” of vaccine

    • No exportation of vaccine until manufacturing country’s needs are met

CDC/ Judy Schmidt


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Pandemic Preparedness: Vaccine Development Strategy (GlaxoSmithKline)

  • Strategies “guided” by the public health community

  • WHO is expected to coordinate these efforts

  • Manufacturers are being encouraged to develop vaccines that will meet global demand

  • Countries/regions are being encouraged to articulate their needs/plans for

    • Demonstrating burden of seasonal influenza

    • Seasonal influenza vaccine

    • Pandemic influenza vaccine


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WHO Strategy to Increase Pandemic Influenza Vaccine Capacity (GlaxoSmithKline)

  • Development of immunization policy to reduce seasonal influenza burden

    Will increase demand for seasonal influenza vaccines

  • Increase influenza vaccine production capacity

  • Research and development for more effective influenza vaccines


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1. Develop Seasonal Immunization Policies (GlaxoSmithKline)

Objectives

1. Reduce disease burden from seasonal influenza infections

2. Increase manufacturing capacity for influenza vaccines

Strategy 1:WHO Regional Offices develop plans with input from member states for seasonal influenza vaccination programs. These plans should form the basis for the Global Pandemic Influenza vaccine action planStrategy 2:Mobilize resources to assist in the implementation of a global action plan to increase demand of seasonal influenza vaccine


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2. (GlaxoSmithKline)Increase Influenza Vaccine Production Capacity

Objectives

  • Produce enough vaccine to immunize two billion people within 6 months after transfer of vaccine prototype strain to industry.

  • Produce enough vaccine to immunize the world's population (6.7 billion people)

    Strategy 1: Increase production capacity for inactivated vaccines

    Strategy 2: Explore development of other types of influenza vaccines

    Strategy 3:Assess alternative ways to deliver vaccine


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3. Research and Development for More Effective Influenza Vaccines

Objectives

  • Development of influenza vaccines using new technologies

  • Recommend a research agenda

  • Improve collaboration between academia, industry, regulatory authorities, donors and international organizations

    Strategy 1:Enhance protective efficacy and immunogenicity of

    existing vaccines

    Strategy 2:Develop novel vaccines that induce broad

    spectrum and long lasting immune responses

    Strategy 3:Improve evaluation of vaccine performance


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Other Pandemic Preparedness Activities Vaccines

  • Explore use of currently available H5N1 vaccines to prime immunity (prepandemic vaccines)

  • Stockpile of H5N1 antigen in bulk

  • Stockpile of vaccine supplies

  • Increase egg supply

  • Develop capacity for large scale influenza immunization programs


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Preparedness Management and Coordination Vaccines

  • Technology transfer of cell culture technique to developing countries

  • Mechanism for funding investments to increase vaccine production capacity

  • Develop a management/coordination strategy (responsibilities, leadership, WHO role)

  • Define a mechanism for the flow of donor funds


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Review Question 4 Vaccines

What are the three WHO strategies for increasing pandemic vaccine capacity?

Answer:

  • Development of immunization policy to reduce seasonal influenza burden

  • Increase in influenza vaccine production capacity

  • Research and development for more effective influenza vaccines


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Summary Vaccines

  • Increasing (but still limited) use of seasonal flu vaccines in developed countries

  • Linking increased use of seasonal flu vaccine to a strategy for pandemic preparedness

  • Need consensus:

    • Strategies for use of prepandemic vaccine

    • Development and management of stockpile

    • Evolving role of WHO to manage pandemic vaccine stockpile


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Glossary Vaccines

Immunogenicity: Capability of inducing an immune response

Antigen: A substance that stimulates the production of an antibody when introduced into the body. Antigens include toxins, bacteria, viruses, and other foreign substances.

Antibody: A Y-shaped protein on the surface of B cells that is secreted into the blood or lymph in response to an antigenic stimulus, such as a bacterium, virus, parasite, or transplanted organ. Antibodies bind antigens and mark them for destruction or prevent cells from being infected. Antibodies are antigen specific.

Antibody Response: The immune system responds to antigens by producing antibodies. Antibodies produced in response to an antigen work best on that antigen, but might have some activity against similar antigens.


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Glossary Vaccines

Clade: A group of organisms, such as influenza viruses, whose members share homologous features derived from a common ancestor.

Reactogenic: the capacity of a vaccine to produce adverse reactions

Subvirion: An incomplete viral particle (e.g. like the HA antigen).


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