Presentation on theme: "Seasonal and Pandemic Influenza Vaccines:"— Presentation transcript:
1 Seasonal and Pandemic Influenza Vaccines: Vaccine Development and ProductionIn this session we will be discussing seasonal and pandemic influenza vaccines, focusing on their development and production. This slide set was developed by the Influenza Division, National Center for Immunizations and Respiratory Diseases, US Centers for Disease Control and Prevention.
2 Learning ObjectivesDevelop a basic understanding of how influenza vaccines are developedBe familiar with the major types of vaccines and methods of vaccine productionUnderstand the importance of vaccine effectiveness and testingThe learning objectives for this module are to:Develop a basic understanding of how influenza vaccines are developedBe familiar with the major types of vaccines and methods of vaccine productionUnderstand the importance of vaccine effectiveness and testing
3 Outline Overview of vaccine production Seasonal influenza vaccination Progress in developing vaccines for influenza viruses with pandemic potentialThe first part of this module will focus on the main issues surrounding seasonal and pandemic vaccine production and planning. First we will give an overview of how vaccine is produced. Then we will describe seasonal influenza vaccination including vaccine effectiveness and a brief review of vaccination recommendations and supply worldwide. Then, progress in pandemic vaccine development will be briefly described.
4 Overview of Vaccine Production Let’s start by giving an overview of seasonal and pandemic vaccine production.
5 To understand how the vaccine is produced we need to know a little bit about the virus. This is a crude drawing of the virus that highlights the key role played by two protein molecules on the surface of the virus. When a person is infected with influenza virus or vaccinated, his or her immune system responds to these proteins. These proteins are called hemagglutinin and neuraminidase.New viral strains appear as the HA & NA gradually change over time. Minor changes appear frequently and accumulate- this is called genetic “drift.” Over time and as the strains “drift”, persons who have been previously infected or vaccinated no longer have good immunity to new drifted strains. This is the reason why influenza vaccines are updated each year and why people can get several flu illnesses in their lifetime.Sometimes a more extensive change in the hemagglutinin appears – this occurs infrequently and is called antigenic “shift”. Persons who have been previously vaccinated or infected have very little or no immunity to these new strains. These changes can lead to pandemic influenza strains.
6 The influenza virus has other components also, which are depicted in a slightly more complex drawing here. These other components are important in viral replication and pathogenesis.For example, the M1 protein is a matrix protein, important for virus assembly. The M2 protein is part of the ion channel; this is a part of the virus that allows ions in and out of the virus envelope. And of course you are already familiar with the hemagglutinin and neuraminidase surface proteins, which function to attach the virus to a host cell and help release virus particles from the cell, respectively.
7 Approaches to Influenza Vaccine Development Subtype/strain-specific vaccines:Induce immune response to hemagglutinin (HA) and neuraminidase (NA) viral proteinsExamples: Inactivated influenza virus vaccines, Live-attenuated vaccines, virus-like particlesUniversal vaccinesCurrent area of investigationImmunize with conserved proteins (for example: M2)Broad-based immunityImmune response against multiple subtypesOne approach to developing influenza vaccines relies on specific influenza antigens. Vaccines are designed to induce strain-specific immunity against particular hemagglutinin and neuraminidase proteins. This approach is currently used for all influenza vaccines, including injected and live attenuated vaccines. Because these proteins vary from year to year, the vaccine strain also has to be reviewed and often replaced each year. Each year, the WHO uses strain surveillance data to make predictions about circulating strains for each hemisphere. If the influenza strains that circulate are different than the prediction, the vaccines may not provide full immune protection against the circulating viruses.Another approach to vaccine development is to make a universal vaccine. Some influenza proteins are conserved over time, meaning they do not change very much. A vaccine against these proteins, such as M2 has the potential to stimulate broad-based immunity against multiple subtypes of influenza and could be affective for more than one influenza season. This is currently an area of investigation, but there are not universal vaccines available yet.
8 Composition of Vaccines against Seasonal Influenza Three strains selected to make a trivalent vaccineBased on global viral surveillanceSelection decision precedes typical peak influenza season by monthsNorthern Hemisphere strains selected in FebruarySouthern hemisphere strains selected in September“New vaccine” (one or more new strains) every yearNow lets talk about specifically about how the seasonal vaccine is made. Every year, three virus strains are selected to make a trivalent vaccine against seasonal influenza. These three strains selected are based on global viral surveillance. The selection decision is made before the typical peak of the influenza season – by about months. This means that for the upcoming year, Northern Hemisphere strains are selected in February and Southern hemisphere strains are selected in September. The result is that there is usually at least one new strain in each vaccine each season.
9 Types of Influenza Vaccines Non-Replicating VaccinesReplicating VaccinesAntigens are manufactured outside the hostInactivated Whole or split virusRecombinant protein Single protein, virus-like particlesPeptideAntigens are replicated in hostLive attenuated vaccines Replication restricted to the cooler upper airwaysMicrobial vector vaccines Bacterial vectors deliver DNA or RNA to hostDNA vaccinesThere are 2 basic types of influenza vaccines. The antigen in the vaccine can be manufactured outside the host – this is known as a non-replicating vaccine. Or the vaccine virus can actually replicate in the host cells, much as it would in a natural infection – this is known as a replicating vaccine.The antigens in non-replicating vaccines are manufactured and then administered to the host. These vaccines include the currently available inactivated vaccines, which are injected whole and split virus preparations, as well as vaccines in development such as recombinant protein vaccines and peptide vaccines.Replicating vaccines might offer the advantage of being better at stimulating an immune response. These vaccines use the host-cell machinery to replicate in the same way that the actual virus or viral proteins would, thus stimulating an immune response that is similar to that needed for infection with the real virus. These vaccines include the currently available intranasal live attenuated vaccines, which replicate poorly at core body temperature but can replicate, and stimulate a mucosal immune response, in the cooler upper airway. Other replicating vaccines in development include other live attenuated vaccines, microbial vector vaccines and DNA vaccines.
10 Egg-based Manufacturing of Inactivated Influenza Vaccines Must maintain flocks and viable eggsBacteria inherent on surface of eggsSeed viruses must be adapted to eggsNot set-up for high-level bio- containmentCannot use wild type highly pathogenic virusesCurrently nearly all available vaccines are manufactured using embryonated chicken eggs. This has a number of disadvantages, including the requirement to maintain a flock of birds and viable eggs, the need to get rid of the bacteria present on the surfaces of eggs, and the requirement for egg-adaptation of seed viruses that are candidates for vaccines, which can change the immunogenic characteristics of the viruses. In addition, manufacturing processes involving eggs typically are not set up for high level biocontainment. This limits, for example, the ability to use highly pathogenic wild type virus in egg-based vaccine production.CDC/ Dr. Stan Foster
11 Cell-based Manufacturing of Inactivated Influenza Vaccines Storage in a working cell bankFermenter for growth of tissue culturesRequirement for special supplements:Carrier beads (to maximize cell growth surface area)Protease or growth additivesVariable replication efficiency: wild type and “high growth” reassortantsManufacturing with high biocontainment (BSL3) must be used for highly pathogenic strainsTo address some of the problems with egg-based vaccine manufacturing, cell-based techniques have been developed. These techniques present their own challenges, as detailed on this slide, such as:The need to store the tissues in a working cell bank;The need to use a fermenter for amplification and optimal growth of tissue cultures;There may be special requirements for development and supplementation to grow the tissues, such as carrier beads, which are used to maximize the cell growth surface area, and protease or other growth additives;Replication efficiency can be an issue, with growth of not only wild type viruses but also undesired “high growth” reassortants;Manufacturing with high levels of biocontainment must be used, for example if highly pathogenic avian viruses are being cultured.Despite these drawbacks, there is considerable interest in moving towards cell-based manufacturing. Vaccines manufactured using cell-based processes will likely be available for commercial use within the next few years.
12 Production of Seasonal Influenza Vaccines (U.S. example) This figure shows the timeframe for vaccine development, manufacture and distribution in the United States, where influenza seasons typically occur between October and April. First, global surveillance data is used to select three strains for the following influenza season’s vaccine. These decisions are made by an FDA advisory panel using virologic information and strains provided by the CDC and others. The strains are then distributed to manufacturers and vaccine is produced. The FDA then tests the vaccines and approves or licenses them. Manufacturers produce the season’s vaccines, fill them into ready-to-use vials and syringes, and package them for distribution. The product is shipped out, and vaccination begins. Vaccination typically begins by October and extends though the end of the calendar year and the winter months.Jan-MarApr-JunJul-SepOct-Jan
13 Constraints with Current Seasonal Vaccines Selection of strains difficult and time consumingAnnual, seasonal productionTechnical process, specialized facilitiesLack of cross protection against antigenic variantsLong term protection uncertainRelatively high costAnnual vaccine administration is requiredAlthough current seasonal vaccines are fairly effective and quite safe, there are important constraints on their more widespread use.Selection of strains is difficult and very time consuming.The time required to produce the vaccines means that currently circulating strains might not be well represented or covered in the following season.These vaccines are relatively costly to make.The technical process of production requires large specialized facilities.Importantly, cross protection after vaccination against antigenic variants and drifted strains is quite variable but usually reduced, and protection is not likely to by long-lasting.Finally, the vaccines must be administered annually.
14 Review Question 1What type of manufacturing is most commonly used for influenza vaccines?Egg-basedCell-culture basedReverse geneticsNone of the aboveAnswer: A. Currently available vaccines are manufactured using embryonated chicken eggs or egg-based manufacturingWhat type of manufacturing is most commonly used for influenza vaccines?Egg-basedCell-basedLaboratory-basedNone of the aboveAnswer: A. Currently available vaccines are manufactured using embryonated chicken eggs or egg-based manufacturingOther frequent answer choices:Cell-culture (Incorrect. This technology has been developed for influenza vaccine production, but it is not yet commonly used)Reverse genetics (Incorrect, this is a method of vaccine development, but is not used for manufacturing)
15 Seasonal Influenza Vaccination: Safety and Effectiveness Now that you understand how the vaccines are produced, in the next section we will talk about the safety, effectiveness, and some of the programmatic aspects of seasonal influenza vaccination.
16 Antibody Response to Influenza Vaccination Post-vaccination antibody correlates with protectionPeak antibody response 2 weeks after vaccination in people needing only one doseImmunity wanes during the yearLasts through the influenza seasonRequires annual vaccinationHow effective vaccination is going to be in preventing influenza is often predicted by using the antibody response to vaccination as an indicator. A satisfactory level of post-vaccination antibody correlates with immune protection.The level of antibody varies, however, depending at the time at which it is measured. The peak antibody response occurs 2 weeks after vaccination in people needing only one dose. Immunity wanes during the year, but lasts through the influenza season. Because of waning immunity and varying circulating virus strains, maintaining antibody protection requires annual vaccination.
17 Determinants of Antibody Response to Influenza Vaccines AgeElderly and young children can have lower antibody responsePrior exposure to virus strains similar to those in vaccine (infection or vaccination)Immune competence of person being vaccinatedAmount of antigen in vaccineType of vaccinePresence of adjuvantsAntibody response can also vary between individuals and groups. For example, the very young and the elderly can have lower antibody response compared to school-aged children and non-elderly adults, but persons with previous exposure to virus strains similar to those in the vaccine (either because of previous infection or previous vaccination) will usually have a better antibody response.The immune competence of the person being vaccinated will affect response.A larger amount of antigen in the vaccine can produce a better response, although a point of diminishing returns is often reached as antigen amounts are increased.The type of vaccine affects the immune response. Live attenuated vaccines might provide a better immune response, but this response is more difficult to measure because it requires measuring types of immune responses beyond those that can be measured using serologic samples. Whole virus inactivated vaccines can be more immunogenic, but are also more likely to cause adverse reactions to the vaccine.Finally, the presence of adjuvants is a determinant of antibody response. Adjuvants are substances which can increase the immune response.
18 Measuring Effectiveness of Seasonal Influenza Vaccine Effectiveness varies by age group, risk group, and antigenic matchDifferent study methods make comparisons difficultObservational studies: Easier to do but differences between vaccinated and unvaccinated persons can bias resultsRandomized controlled trials: Reduce bias, but costlyVariety of outcomes can be measured that make comparisons between studies difficultLess specific: Influenza-like illness (ILI)More specific: Laboratory-confirmed influenzaSo vaccine effectiveness will vary according to the age group, influenza risk group, and the degree that the vaccine strains match the circulating strains (antigenic match). How, then, can we measure the effectiveness of a seasonal influenza vaccine, with all of these variations to consider?One of the challenges studying the effectiveness of seasonal influenza vaccination is that different study methods Effectiveness estimates using severe outcomes such as hospitalization or death are usually done by observational studies, but interpretation of these studies can be difficult or impossible if there are too many differences between vaccinated and unvaccinated people that bias the results. These studies can overestimate the effectiveness of vaccination if the sample is biased because healthier persons tend to be preferentially vaccinated. Randomized controlled trials are often considered a gold standard method because they reduce bias, but they can be costly.The choice of outcome measure can also make comparisons difficult. The variety of different outcomes used to assess effectiveness has made comparisons between studies difficult.Some outcomes used to assess effectiveness are often less-specific, such as influenza-like illness or ILI, which is usually defined as acute onset of fever and either cough or sore throat. By “less-specific” we mean that syndromes like ILI (e.g. fever with cough and/or sore throat) can be caused by a variety of respiratory pathogens or even non-infectious etiologies. However, influenza vaccine is only going to prevent ILI caused by influenza virus. Therefore effectiveness estimates that use ILI as an outcome typically find the vaccine has a relatively low effectiveness.Effectiveness measured by more specific measures such as laboratory-confirmed influenza is typically much higher, but requires more expensive and carefully designed studies.
19 Effect of Co-circulation of Non-influenza Pathogens/Outcome Specificity on VE Estimate The effect of choosing a nonspecific outcome on vaccine effectiveness is shown by looking at the following two situations. In Situation A and Situation B, vaccine effectiveness against lab-confirmed influenza, shown by the red bars - is identical. However if a less specific outcome measure like ILI is used, the contribution of other respiratory illnesses (yellow bars) affects the vaccine effectiveness estimate. In situation A, lab confirmed influenza makes up a substantial proportion of illnesses, and one would likely be able to show the vaccine had some effectiveness against lab confirmed influenza. In situation B however lab confirmed influenza makes up a smaller portion of the causes of ILI. Vaccine effectiveness would be fairly low, and might not even be detectable unless a fairly large study were done. Thus an understanding of what outcome is being measured is critical to interpreting influenza vaccine effectiveness studies.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.
20 Inactivated Seasonal Influenza Vaccine Effectiveness, by Age and Risk Group, when Vaccine Strains Match Circulating StrainsAge/Risk groupOutcomeEffectiveness*6 months-18 yearsInfluenza**50-90%18-64 years>65 years, community50-70%Elderly, nursing home30-40%Hospitalization or death40-80%This table shows the wide range in effectiveness estimates that have been measured by age group or risk group, in influenza seasons.These comparisons have been made when the vaccine matched well with circulating strains, and the outcome is laboratory-confirmed influenza. Effectiveness of the vaccine will be lower when vaccine and circulating strains are antigenically different. No vaccine effectiveness is sometimes observed when vaccine strains are very different from circulating strains of flu virus.*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
21 Global Distribution of Influenza Vaccines, 1994-2003 The number of persons who are given influenza vaccine each year is often indirectly estimated the number of doses distributed. You can see here that the number of doses distributed has gone up not only in Western Europe, Canada and the United States, but also in the rest of the world. The number of doses distributed has approximately doubled over a 10 year period overall. However, because populations in parts of the world outside of North America and Western Europe are so much larger, these data indicate that coverage is much lower in other parts of the world.WHO Global Influenza Vaccine Distribution
22 Review Question 2What are some of the individual or demographic attributes that affect vaccine effectiveness?Answers:AgeImmunocompetenceAmount of antigen present in vaccineVaccine typePrior exposure to similar viral strainsWhat are some of the individual or demographic attributes that affect vaccine effectiveness?Answers:AgeImmunocompetenceAmount of antigen present in vaccineVaccine typePrior exposure to similar viral strainsFor Lectora: Incorrect response options include:Method of administrationPrior infection with non-influenza virusesLaboratory
23 Developing Vaccines for Influenza Viruses with Pandemic Potential Now we will discuss progress and challenges in pandemic influenza vaccine development.
24 From Seasonal to Pandemic Influenza Vaccine Production Manufacturing facilities could shift production from seasonal vaccine to pandemic vaccinesPandemic vaccines will not available at beginning of pandemicLikely available within 4-6 monthsOnce available, there will be limited quantities initiallyBy this time there might be wide spread circulation of the pandemic strainFirst, let’s put pandemic influenza vaccine production into perspective.If an influenza strain with pandemic potential is identified, facilities that make seasonal influenza vaccine could shift to making pandemic vaccine. However, the reality is that pandemic vaccines will likely not be available at the beginning of a pandemic using currently available manufacturing techniques. Vaccine is likely to be available within 4 to 6 months after declaration of pandemic.In addition, once pandemic vaccines do become available, there will initially only be limited quantities available for the first several months. By this time there might be wide spread, and perhaps global, circulation of the pandemic strain.
25 Challenges to Development of Vaccines against Influenza A (H5N1) Reduced immunogenicity compared to seasonal influenza vaccines, unless formulated with an adjuvantExpenseReduced yield in egg-based manufacturing processesHigh antigen contentProprietary adjuvantsUnknown cross protection against other cladesPredictive value of pre-clinical studies not establishedDeveloping vaccines against influenza viruses with pandemic potential, such as influenza A(H5N1) viruses, is a major research and development challenge. The vaccines available thus far have not had the same immunogenicity compared to seasonal influenza vaccines, unless formulated with an adjuvant.The result is that making these vaccines using current technologies is expensive. In addition to increased manufacturing costs due to relatively poor yield using the traditional egg-based manufacturing processes, the vaccines have either required a high antigen content or proprietary adjuvants in order to stimulate a protective immune response.Another challenge is that the cross protection against other clades is unknown, and since we don’t know which influenza virus is the most likely to acquire pandemic potential this necessitates development of vaccines against multiple clades. In addition, since the virus is not yet circulating, the predictive value of pre-clinical studies is not established as well as it is for seasonal influenza vaccines.
26 Priorities in Development of Pandemic Influenza Vaccines Evaluation of dose-sparing strategies including use of adjuvantsAccelerated development of cell-culture based vaccinesNovel approaches to vaccine development Including vaccines that provide broad cross protectionBased on the challenges identified on the previous slide, several priorities in the Development of Pandemic Influenza Vaccines have become clear:First, evaluation of dose-sparing strategies including use of adjuvants needs to continue as an active area of investigation.Secondly, development of cell-culture based vaccines that might be easier and quicker to produce needs to be accelerated.Finally, novel approaches to vaccine development are needed, especially the development of vaccines that provide broad cross protection across clades .
27 Potentially Pandemic Viral Strains under Study H5N1Multiple cladesH9N2H7N7H5N2Swine-origin novel influenza A(H1N1)Studies are being planned or are underway to determine dosing, safety, and antibody response to a number of vaccines directed against influenza A viruses with pandemic potential, including several clades of H5N1 viruses, H9N2 viruses, H7N7 viruses, H5N2, and swine-origin novel influenza A(H1N1).
28 Immunogenicity of a Candidate Influenza A (H5N1) Vaccine (Sanofi) (A/Vietnam/1203/H5N1; Clade 1) Vaccine dose (ug)GMT at baseline28 days after 1st dose of vaccineNo % with tested HI >1:4028 days after 2nd dose of vaccineGMT after 2nd dose9010.49928%57%46.34510.89523%9341%34.71510.310010%24%20.37.511.45%13%14.9Placebo10.6480%10.9This slide describes a new trial of an inactivated candidate vaccine against influenza A(H5N1) from Sanofi.The trial illustrates the promise and the challenges associated with developing these vaccines. This was a dose-ranging trial in which doses up to 90 micrograms were given intramuscularly in a 2 dose series to several hundred healthy adult volunteers. Recall that seasonal influenza vaccines contain 15 micrograms of each of the three virus strains.The vaccine was well tolerated, and many vaccinees had a measurable dose-dependent response to vaccination as indicated by the rise after the second dose in the geometric titer shown in the far right column. However, even after 2 doses of the 90 microgram formulation, only 57% of vaccinees had hemagglutinin inhibition, or HI titers greater than or equal to 1 to 40, shown in the second column form the right. HI titers greater than or equal to 1 to 40 is the antibody response level that is thought to indicate immunity after vaccination.Treanor et al. N Eng J Med 2006;354:
29 Influenza A (H5N1) Clade 1 Vaccine with Adjuvant (GlaxoSmithKline) Inactivated influenza A (H5N1) clade 1 antigen and proprietary adjuvantDesign:Placebo-controlled, ~400 healthy adults2 doses vaccine +/- adjuvant in doses from 3.8 to 30 microgramsResults:Adjuvanted formulations more immunogenicGood antibody response (even at 3.8 micrograms)Induced cross-reactive antibody responses against clade 2 strainMet FDA requirements for licensureA more recent study using an inactivated H5N1 vaccine with an adjuvant showed that smaller amounts of antigen (antigen-sparing) might be possible for the vaccines. In this trial an inactivated influenza A (H5N1) clade 1 vaccine was given to healthy volunteers. The vaccine was given in 2 doses in formulations with and without adjuvant in doses ranging from 3.8 to 30 micrograms.The results indicated that the adjuvanted vaccines were more immunogenic – and were immunogenic even with antigen doses as low as 3.8 micrograms. They were also slightly more reactogenic (more injection site reactions), but these were mostly mild reactions.The vaccine stimulated good antibody responses in most participants in doses as as low as 3.8 micrograms.In addition, the vaccine induced cross-reactive antibody to a reverse engineered clade 2 virus in 75% of participants, and also met US FDA requirements for licensure.Leroux-Roels et al. Lancet. 2007;370(9587):580-9.
30 Candidate Influenza A (H5N1) Vaccines: Experience to Date Inactivated subvirion vaccines: Immunogenicity suboptimalHigh antigen content required (90 micrograms)Require 2 dosesFew adverse eventsAdjuvanted inactivated subvirion vaccinesSimilar or better response compared to subvirion vaccinesWithout adjuvant at doses as low as 3.8 micgrgramsNeed for 2 doses less certainAntigen sparing (reduced antigen content needed)Proprietary adjuvants have shown best antigen-sparing effectsIncreased reactogenicity with adjuvantsIn summary, this is the experience to date with the two types of vaccines for which there is the most experience to date.Among the various inactivated subvirion candidate vaccines:Immunogenicity has been suboptimal, a high antigen content has been required (90 micrograms) and also 2 doses have been needed. The good news is that there have been few adverse events.Among the adjuvanted inactivated subvirion vaccines:The response after vaccination has been usually better than that after the subvirion vaccines without adjuvant at doses as low as 3.8 micrograms, and because of this, the need for 2 doses less certain.Antigen sparing (reduced antigen content) has been demonstrated, and proprietary adjuvants have shown the best antigen-sparing effects.However, increased reactogenicity from vaccines with adjuvants has been observed.There are many other promising vaccine development strategies underway for making vaccines against influenza A viruses with pandemic potential, including live attenuated vaccines and vector-based vaccines. In the interest of time we will not discuss those specifically. Reviews describing these other vaccine strategies are available in the literature.
31 Target paradigm of an ideal H5N1 pandemic vaccine From: S Sambhara, CB Bridges,GA Poland. Lancet 2007.This diagram illustrates the “target” of creating an ideal vaccine that could be provided before a pandemic, and directed against a strain with pandemic potential. Problematic characteristics or vaccine challenges are listed in the outer ring, pointing toward potential solutions in the inner rings until the ideal vaccine target is reached in the center.Until recently, researchers were only beginning to understand the outer ring of this target. For example, we did not know if there would be cross immunity against other clades. However, recent studies are advancing the state of current knowledge towards the inner ring. Initial assessments of cross reactive responses and dose sparing are completed. A better understanding of long term potency and follow up studies to assess durability of the antibody response are underway. However, we still have much work to be done before the inner target is reached.
32 Review Question 3Which technology that might be used to reduce the dose of antigen that is needed in a vaccine?Cell-based technologyAdjuvantsUniversal vaccineNone of the aboveAnswer:b. AdjuvantsWhich technology that might be used to reduce the dose of antigen that is needed in a vaccine?Cell-based technologyAdjuvantsUniversal vaccineNone of the aboveAnswer:b. Adjuvants
33 SummaryProduction using traditional methods will not meet global demand for a pandemic vaccineH5N1 Vaccines produced using traditional seasonal influenza vaccine methods have relatively poor immunogenicityImproved with use of adjuvantsConsiderable progress with alternative vaccinesIn summary, several important points that need to be remembered about currently available candidate vaccines for use against influenza viruses with pandemic potential. First, Production using traditional methods will not meet global demand. Second, Vaccines produced using traditional seasonal influenza vaccine methods have relatively poor immunogenicity. This appears to have been much improved with the use of with use of adjuvants, but at the cost of some increase in adverse events associated with vaccination. Lastly, there has been considerable progress with the development of alternative vaccines – both in vaccines with different mechanisms of delivery as well as vaccines that improve or supplement protective immune responses
34 GlossaryAntigen: Are proteins or polysaccharides that are parts of viral or bacterial structure and which prompt the immune system responseAdjuvant: 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 facilitiesGenetic 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.
35 GlossaryEmbryonated: 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
36 GlossaryClades: 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.
37 GlossaryTrivalent 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 stagesAntibody 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.
38 Glossary(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.
39 Seasonal and Pandemic Influenza Vaccines: Programmatic Issues and Pandemic Preparedness Welcome to the second part of the module on seasonal and pandemic influenza vaccines. In this session we will cover programmatic issues and pandemic preparedness regarding seasonal and pandemic vaccines
40 Learning ObjectivesRecognize the differences and challenges of seasonal vs. pandemic influenza vaccine development, manufacturing, and distributionThe learning objective for this session is to recognize the differences and challenges of seasonal vs. pandemic influenza vaccine development, manufacturing, and distribution.
41 Outline Vaccine capacity Vaccine access Planning WHO strategies Several key programmatic issues need to be addressed in this section, including vaccine capacity, access and planning, and the WHO strategies for increasing production and capacity.
42 Pre-pandemic: Vaccine Planning Definition: Vaccines developed against influenza viruses that are currently circulating in animals and that have the potential to cause a pandemic in humansRationale: might provide priming or “limited protection” against pandemic strainGoal: Reduce morbidity or mortalityMight not reduce number of viral infectionsProblem: Which vaccine strains, and when should it be given?Earlier we said that a specifically matched pandemic vaccine would not be available in the initial stages of a pandemic in most likely scenarios. Pre-pandemic vaccines are vaccines developed against influenza viruses that are currently circulating in animals and that have the potential to cause a pandemic in humansA pre-pandemic vaccine developed from currently circulating strains might provide “priming” or limited protection against pandemic strain. The goal of the pre-pandemic vaccine would be to reduce morbidity or mortality, i.e., influenza severity, even if the vaccine might not substantially reduce the number of influenza viral infections.The problem is that we don’t know which vaccine strains to use. Nor do we know when such a vaccine should it be given. However, these scientific issues are only one part of the problem of figuring out how to plan for responding to the threat of a pandemic with a vaccine program.
43 Pandemic Preparedness: 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 courses65% of capacity is located in Europe85% of influenza production is by 3 companiesCountries with manufacturing capacity represent 12% of global populationFirst, vaccine supply is an important issue for any future pandemic. The current global production capacity is limited. Currently only approximately 300 million doses of trivalent vaccine can be produced on an annual basis. For a monovalent vaccine there is capacity for 900 million doses, but a 2-dose course may be necessary to elicit immunity which means there will be 450 million courses available.65% of vaccine manufacturing is located in Europe, and 85% of vaccine production is by 3 companies. Countries with a manufacturing facility represent only 12% of the global population – these countries, not surprisingly, now use 62% of seasonal influenza vaccine.
44 Pandemic Preparedness: Global Response Increasing pressure from developing countries for access to influenza vaccineWhen pandemic declared, potential for:“Rationing” of vaccineNo exportation of vaccine until manufacturing country’s needs are metDeveloping countries are concerned about ensuring access to vaccines for their populations, particularly in view of the fact that many candidate virus strains are being isolated in their countries.Global response and availability is also an important issue. When a pandemic is declared there is potential for “rationing” of the vaccine supply, and that can be problematic. But this will be necessary in one form or another at the start of a pandemic when vaccine is in short supply.In addition, manufacturing countries might not export vaccine until their own needs are met.CDC/ Judy Schmidt
45 Pandemic Preparedness: Vaccine Development Strategy Strategies “guided” by the public health communityWHO is expected to coordinate these effortsManufacturers are being encouraged to develop vaccines that will meet global demandCountries/regions are being encouraged to articulate their needs/plans forDemonstrating burden of seasonal influenzaSeasonal influenza vaccinePandemic influenza vaccineVaccine development and production strategy should be “guided” by the public health community. The WHO is expected to coordinate these efforts between countries.Manufacturers are being encouraged to use a variety of approaches to develop vaccines that will meet global demand. To help develop and refine global vaccine strategy, countries and regions are being encouraged to articulate their need/plans for both seasonal influenza vaccine and pandemic influenza. Demonstrating the burden of seasonal influenza in developing countries is therefore central to generating the interest and capacity to produce seasonal or pandemic vaccines.A little bit more about the WHO strategy for increasing vaccine production capacity follows.
46 WHO Strategy to Increase Pandemic Influenza Vaccine Capacity Development of immunization policy to reduce seasonal influenza burdenWill increase demand for seasonal influenza vaccinesIncrease influenza vaccine production capacityResearch and development for more effective influenza vaccinesThe WHO has outlined a strategy for increasing the influenza vaccine production capacity necessary for responding to an influenza pandemic. This strategy has three distinct parts which will talk about in the next couple slides but first to introduce the global strategy:First, member states are being encouraged to develop an immunization plan for seasonal influenza. There is increasing evidence in recent years that influenza is an important but under-diagnosed cause of acute respiratory illness in developing countries, even those in tropical regions.Second, increasing demand for seasonal influenza vaccine would stimulate a corresponding increase and diversification of influenza vaccine production capacity.Lastly, WHO continues to promote research and development for more effective influenza vaccines. The next three slides provide some specifics on how WHO proposes to achieve these objectives.
47 1. Develop Seasonal Immunization Policies 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 plan Strategy 2: Mobilize resources to assist in the implementation of a global action plan to increase demand of seasonal influenza vaccineThere are two main objectives to the WHO initiative of encouraging country-specific development of an immunization policy for seasonal vaccines.The first objective is to reduce the disease burden from seasonal influenza infections and the second to increase manufacturing capacity for influenza vaccines. These objectives will be met through two strategies:Strategy 1: WHO Regional Offices should 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 plan andStrategy 2: WHO and member states are asked to mobilize resources to assist in the implementation of a global action plan to increase demand of seasonal influenza vaccine
48 2. Increase Influenza Vaccine Production Capacity ObjectivesProduce 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 vaccinesStrategy 2: Explore development of other types of influenza vaccinesStrategy 3: Assess alternative ways to deliver vaccineTo increase influenza vaccine production capacity, WHO has developed the following additional objectives: 1) Produce enough vaccine to immunize two billion people within 6 months after transfer of vaccine prototype strain to industry, and 2) Produce enough vaccine to immunize the world's population (6.7 billion people).These objectives are approached through three specific strategies: 1) Increase production capacity for inactivated vaccines, 2) Explore other types of vaccines, and 3) Assess alternative ways to deliver vaccination
49 3. Research and Development for More Effective Influenza Vaccines ObjectivesDevelopment of influenza vaccines using new technologiesRecommend a research agendaImprove collaboration between academia, industry, regulatory authorities, donors and international organizationsStrategy 1: Enhance protective efficacy and immunogenicity ofexisting vaccinesStrategy 2: Develop novel vaccines that induce broadspectrum and long lasting immune responsesStrategy 3: Improve evaluation of vaccine performanceFinally, the last part of the WHO plan is to encourage research and development for more effective vaccines. This is the focus of 3 further objectives: 1) Development of influenza vaccines using new technologies, 2) Recommending a research agenda, and 3) improving collaboration between academia, industry, regulatory authorities, donors and international organizations. Three strategies accompany these objectives: 1) Enhance protective efficacy and immunogenicity of existing vaccines, 2) Develop novel vaccines that induce broad spectrum and long lasting immune responses, and 3) improve evaluation of vaccine performance
50 Other Pandemic Preparedness Activities Explore use of currently available H5N1 vaccines to prime immunity (prepandemic vaccines)Stockpile of H5N1 antigen in bulkStockpile of vaccine suppliesIncrease egg supplyDevelop capacity for large scale influenza immunization programsMany other activities are underway in both the public and private sector. These include:Exploring the utility of H5N1 vaccines as an immune system primer, meaning they could be made available as prepandemic vaccines.Stockpiling of H5N1 antigen in bulkStockpiling of vaccine supplies and necessary personal protective equipment, such as syringes, adjuvants, masks, and gloves.Increasing the egg supplyDevelop capacity for large scale influenza immunization programs
51 Preparedness Management and Coordination Technology transfer of cell culture technique to developing countriesMechanism for funding investments to increase vaccine production capacityDevelop a management/coordination strategy (responsibilities, leadership, WHO role)Define a mechanism for the flow of donor fundsVaccine development and production strategy should be “guided” by the public health community. The WHO is expected to coordinate these efforts between countries.Manufacturers are being encouraged to use a variety of approaches to develop vaccines that will meet global demand. To help develop and refine global vaccine strategy, countries and regions are being encouraged to define their vaccine needs and develop plans for both seasonal influenza vaccine and pandemic influenza. Demonstrating the burden of seasonal influenza in developing countries is therefore central to generating the interest and capacity to produce seasonal or pandemic vaccines.Pandemic preparedness activities also include improving management and coordination of technology and funds. For example, some of these activities are:The technology transfer of cell culture technique to developing countriesFunding investments to increase vaccine production capacityDeveloping a management/coordination strategy (responsibilities, leadership, WHO role)Defining a mechanism for the flow of donor funds
52 Review Question 4What are the three WHO strategies for increasing pandemic vaccine capacity?Answer:Development of immunization policy to reduce seasonal influenza burdenIncrease in influenza vaccine production capacityResearch and development for more effective influenza vaccinesWhat are the three WHO strategies for increasing pandemic vaccine capacity?Answer:Development of immunization policy to reduce seasonal influenza burdenIncrease in influenza vaccine production capacityResearch and development for more effective influenza vaccines
53 SummaryIncreasing (but still limited) use of seasonal flu vaccines in developed countriesLinking increased use of seasonal flu vaccine to a strategy for pandemic preparednessNeed consensus:Strategies for use of prepandemic vaccineDevelopment and management of stockpileEvolving role of WHO to manage pandemic vaccine stockpileFinally, some of the most difficult problems dealing with vaccine influenza vaccine production, and especially pandemic vaccine production are programmatic rather than scientific.There is a increasing (but still limited) use of seasonal flu vaccines in developed countries. Studies that assess the burden of influenza disease in developing countries are needed to stimulate interest in vaccination against seasonal influenza. Linking increased use of seasonal influenza vaccine to a strategy for pandemic preparedness might help this pandemic preparedness effort. In addition, consensus will be needed regarding:Strategies for use of pre-pandemic vaccineDevelopment and management of vaccine stockpilesEvolving role of WHO to manage vaccine stockpilesThese programmatic challenges are considerable, but a sense of urgency appears to have been reached which will hopefully move these issues forward. We do not know if a global influenza pandemic will occur, but it is foolish not to prepare for it. As we prepare, additional benefits to human health can be achieved, including improvements in vaccination development and immunization infrastructure.
54 GlossaryImmunogenicity: 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.
55 GlossaryClade: 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 reactionsSubvirion: An incomplete viral particle (e.g. like the HA antigen).