02 similarities & differ bw vacc n drugs


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  • Vaccines are also medicines in that they are used to prevent certain diseases. As with all other medicines, vaccines may also be associated with risk of adverse reactions. Medicines,in general are much more likely to cause adverse reactions due to various reasons, however, the tolerance to such adverse effects appear to be lower for vaccines compared to medicines used for treating diseases. Both vaccines and medicines are composed of various ingredients all of which may contribute to an adverse drug reaction. Many drugs also need to have a cold chain maintained. As with all medicines, vaccines need to also go through the process of testing for safety, efficacy and quality and these properties need to be maintained throughout the life cycle of the medicine.
  • Specific issues related to vaccines: PROMOTION Vaccination is implemented to achieve public health goals- the aim is improving the health of populations, rather than individuals. The state has a vested interest in the immunization programme. The involvement of the state in the immunization programme may be perceived as a source of bias when safety issues are investigated. The immunization programme aims to increase vaccine coverage. An investigation into an adverse event may produce results that impact negatively on the goal of achieving complete vaccine coverage. (For example, the adverse event may be publicised and this will heighten the concerns of the public about issues of vaccine safety.) If the immunization programme is responsible for adverse event investigating, this may be perceived as a conflict of interests. The close relationship between the vaccine manufacturer and the immunization programme may also be perceived as a conflict of interests when adverse events are investigated.
  • PROCUREMENT, STORAGE AND HANDLING There are very few vaccines, in comparison with registered medicines. There are few manufacturers, and very few countries produce vaccines. Most countries use vaccines which are imported from elsewhere. Vaccines will often be transported for long distances to remote areas before they are administered. Maintenance of the cold chain is very important for certain vaccines.This is also the case for many medicines as well.
  • EFFICACY Efficacy of vaccines is measured at a community/population level. The goal of immunization is the prevention of infectious diseases and ultimately disease eradication. These endpoints of efficacy are usually only demonstrated once a vaccine is marketed and depends on the effective deployment of such vaccines to the population at risk of contracting the vaccine-preventable disease. They are usually given to healthy individuals, often to children as a preventative measure. The efficacy of a vaccine is therefore primarily seen on a public health level, where drops in prevalence of vaccine-preventable diseases can be measured. These benefits are usually less tangible to vaccinees and their care-givers (unless the vaccine-preventable disease is quite prevalent in the community). As vaccination programmes become increasingly successful at achieving the goals of disease eradication, the disease burden falls and the benefits of immunization become even less immediately apparent. For this reason, the public perception of efficacy changes over time.   This differs from medicines used to treat medical conditions. In the latter case, patients and health care providers are usually able to directly perceive a benefit. Moreover, the benefit profile of a medicine usually remains fairly unchanged for the population being treated.   At the time of registration of a vaccine, the efficacy of the vaccine is usually determined through the use of surrogate markers (such as antibody titres), Phase I, II and III trials (see Glossary) and from the experiences of countries where the vaccine is already used.  
  • SAFETY We often vaccinate individuals who are healthy at the time of vaccination. This results in a low public tolerance for adverse events- the perception is that the individual was healthy “until the vaccine made them ill”. The safety of vaccines is often monitored within the immunization programme. If officials from the immunization programme are responsible for investigating adverse events related to administration of a vaccine, this may be perceived as a conflict of interests. There is a need for independent review of adverse events, separate from the immunization programme. Causality assessment requires a team of investigators, (including input from an immunologist ) It is important that reports of specific events, particularly programme errors, be solicited Additional notes With regards to safety monitoring of vaccines, there are several special considerations which could affect the type of immunization surveillance programme implemented. Due to the fact that vaccines are administered to well, healthy-looking infant and children, the level of tolerance for any adverse event is very much lower than with medicines used to treat medical conditions. As was discussed previously, the regulatory authority is usually the only organisation with the mandate to ensure the safety, efficacy and quality of vaccines. Vaccination programmes could be perceived as being promoters of vaccines and therefore not in an unbiased position to monitor the safety of vaccines. There are special challenges to assessing the causal association between a vaccine and an AEFI. These need to be considered and will be discussed in more detail in the talk on Causality. Special expertise including an immunological opinion is vital when assessing causality. Most AEFI programmes solicit specific reports such as local injection site reactions because they are also interested in programmatic errors rather than just pure vaccine reaction signals. Probably the greatest difference between vaccines and other medicines is the system of lot release. As with other medicines, the quality control of vaccines is used to establish whether the products are safe and potent. The quality control of vaccines usually relies on the control of starting materials, control of the production process, and final product. Traditionally the quality of vaccines used in immunization programmes is measured by potency testing in animal models. Many NRA’s employ a national control authority to conduct independent release of vaccines on a lot-by-lot basis. Very often the pharmacological action of vaccines and the adjuvants which are also present in the preparation are poorly understood, particularly by immunization staff. Moreover, there remain many unanswered questions about possible risks which have never been proven but are widely publicised. Some countries have resorted to providing a compensation plan for proven AEFIs. This is usually not attainable and feasible in developing countries with resource-poor immunization services.
  • How does AEFI reporting interact with ADR reporting? There have been several country scenarios where the EPI programme and NRA have failed to communicate with each other when developing a national AEFI or adverse drug reaction monitoring programme. This has often resulted in duplication of effort and a failure to capture all relevant data in one central repository. In addition, potential crises may go undetected through such confusion and the health care providers may see this as an additional barrier to reporting AEFIs and adverse reactions to medicines.
  • Barriers to reporting Surveillance is dependent on the receipt of timely and accurate reports. Some of the barriers to reporting are listed above. These barriers to reporting can be overcome by: increasing awareness of the importance of reporting, and the system for reporting, and making it easy to report, especially in situations of uncertainty emphasising that investigations are about finding problems with the system and not blaming individuals giving positive feedback for reporting.
  • 02 similarities & differ bw vacc n drugs

    2. 2. SIMILARITIES BETWEEN VACCINES AND MEDICINES <ul><li>Vaccines are also medicines </li></ul><ul><li>Potential for adverse effects </li></ul><ul><li>Multiple ingredients </li></ul><ul><li>Potential for interaction with disease and other medicines </li></ul><ul><li>Also need to comply with standards of safety, efficacy and quality </li></ul>
    3. 3. SPECIFIC ISSUES RELATED TO VACCINES <ul><li>Promotion </li></ul><ul><li>Use on a large scale </li></ul><ul><li>Use may be mandatory </li></ul><ul><li>Public relations: </li></ul><ul><ul><li>we promote the product! </li></ul></ul><ul><ul><li>government has vested interest </li></ul></ul><ul><ul><li>safety issues can be in conflict with programme </li></ul></ul><ul><ul><li>close relationship with manufacturer </li></ul></ul><ul><ul><li>Will any of these differences have an impact </li></ul></ul><ul><ul><li>on the perception of safety of vaccines? </li></ul></ul>
    4. 4. SPECIFIC ISSUES RELATED TO VACCINES <ul><li>Procurement, storage and handling </li></ul><ul><li>About 30 products compared with around 20 000 drugs </li></ul><ul><li>Fewer manufacturers but more recipients </li></ul><ul><li>Maintenance of the cold chain </li></ul><ul><li>Imported vaccines - long distance transport </li></ul><ul><li>How do these factors affect safety surveillance? </li></ul>
    5. 5. Promotion and Procurement: Vaccines vs Drugs <ul><li>Vaccine </li></ul><ul><li>public campaigns </li></ul><ul><li>common </li></ul><ul><li>Politics access/safety </li></ul><ul><li>++government </li></ul><ul><li>procurement / program </li></ul><ul><li>collaboration NIP/gov’t </li></ul><ul><li>and manufacturers </li></ul><ul><li>Drugs </li></ul><ul><li>public campaigns </li></ul><ul><li>rare </li></ul><ul><li>politics access/safety </li></ul><ul><li>++private procurement </li></ul><ul><li>/ programs </li></ul><ul><li>drug manufacturers </li></ul><ul><li>less relationship to </li></ul><ul><li>gov’t </li></ul>
    6. 6. Storage and Distribution <ul><li>Vaccines </li></ul><ul><li>mainly in field, offices and clinics </li></ul><ul><li>cold chain often critical </li></ul><ul><li>biological product- </li></ul><ul><li>lot variation, stability </li></ul><ul><li>Drugs </li></ul><ul><li>mainly in hospitals, </li></ul><ul><li>clinics, pharmacies </li></ul><ul><li>most a room temp </li></ul><ul><li>chemical product </li></ul>
    7. 7. SPECIFIC ISSUES RELATED TO VACCINES <ul><li>EFFICACY </li></ul><ul><li>Given to healthy individuals </li></ul><ul><ul><li>difficult to detect lack of efficacy </li></ul></ul><ul><li>Perceived need depends on disease burden </li></ul><ul><li>Herd immunity </li></ul><ul><li>Goal: disease eradication </li></ul><ul><li>Need vaccine distribution data (batch) </li></ul><ul><li>Brand product specific manufacturing techniques (each product is different) </li></ul><ul><ul><li>Do these factors make our job in safety easier or more difficult? </li></ul></ul>
    8. 8. Efficacy: Vaccine vs Drugs <ul><li>Vaccines </li></ul><ul><li>healthy </li></ul><ul><li>prevention of disease </li></ul><ul><li>large population </li></ul><ul><li>most used in </li></ul><ul><li>infants and children </li></ul><ul><li>Drugs </li></ul><ul><li>ill </li></ul><ul><li>treat disease </li></ul><ul><li>small population </li></ul><ul><li>most used in </li></ul><ul><li>adults </li></ul>
    9. 9. SPECIFIC ISSUES RELATED TO VACCINES <ul><li>SAFETY </li></ul><ul><li>Low public tolerance for adverse events </li></ul><ul><li>Adverse drug reactions are more common </li></ul><ul><li>Safety monitored by “promoters” </li></ul><ul><li>Causality assessment difficult </li></ul><ul><ul><ul><li>need special expertise </li></ul></ul></ul><ul><li>Solicit reporting of specific events </li></ul><ul><li>Lot-by-lot surveillance needed </li></ul><ul><li>Pharmacology not well understood </li></ul><ul><li>Compensation plans for vaccines injury </li></ul><ul><li>How do these factors impact on the </li></ul><ul><li>design of the monitoring system? </li></ul>
    10. 10. Safety and Quality: Vaccines vs Drugs <ul><li>Vaccines </li></ul><ul><li>↑ immunization </li></ul><ul><li>↓ disease burden </li></ul><ul><li>“ benefit” less easy </li></ul><ul><li>to see </li></ul><ul><li>biological product </li></ul><ul><li>immunology </li></ul><ul><li>Drugs </li></ul><ul><li>given with disease </li></ul><ul><li>see benefit case </li></ul><ul><li>for serious disease </li></ul><ul><li>accept AE </li></ul><ul><li>chemical product </li></ul><ul><li>pharmacology </li></ul>Hence for vaccines demand higher quality and safety standards
    11. 11. Adverse Reaction vs Adverse Event: Vaccines and Drugs Adverse reaction (event attributed to Vaccine/Drug) Adverse event All spontaneous reports Events not attributed to vaccine / drug Diseases Other drugs Environment Diet Genetics Compliance * Other factors Programmatic errors
    12. 12. Vaccines vs Drugs Causality Assessment Differences <ul><li>Drugs: challenge/ rechallenge/ dechallenge </li></ul><ul><li>dose-related effect-drugs </li></ul><ul><li>specific marker/ pathognomonic syndrome </li></ul><ul><li>back drop ill health, rarely elective </li></ul><ul><li>pharmacology </li></ul><ul><li>non serious AE not seen as very important </li></ul><ul><li>large numbers of reports </li></ul><ul><li>Vaccines: background of health </li></ul><ul><li>vulnerable age ( infant, elderly) </li></ul><ul><li>“ elective” </li></ul>
    13. 13. Vaccines vs Drugs cont’d <ul><li>Vaccines: complex composition of vaccines </li></ul><ul><li>immunology plus pharmacology </li></ul><ul><li>short duration of exposure yet “long” </li></ul><ul><li>time for response </li></ul><ul><li>may cause disease trying to prevent OPV /VAPP </li></ul><ul><li>↑ non serous AE may indicate program/ </li></ul><ul><li>vaccine problem eg high rate local reactions with 5 th </li></ul><ul><li>dose of DTaP/IPV Canada </li></ul><ul><li>Scheifele D et al. Vaccine 2001; 32: 4720-6 </li></ul><ul><li>much fewer AE reports Argentina 0.3% of all AEs hence </li></ul><ul><li>maybe “lost in shuffle” with minor ones ignored and only </li></ul><ul><li>“ drug” type review done Perez AC, Diez RA. Vaccines in </li></ul><ul><li>Argentina: a regulatory view. Vaccine 2003;21:3492-96 </li></ul>
    14. 14. Safety Monitoring Vaccines vs Drugs <ul><li>Need to ensure that vaccine safety monitoring and causality assessment utilizes system that meets vaccine specific needs </li></ul><ul><li>Build on strengths of drug monitoring BUT modify and adapt to fit vaccines </li></ul>WHO
    15. 15. Adverse drug reaction form AEFI reporting form HOW DOES AEFI REPORTING INTERACT WITH ADR REPORTING?
    16. 16. BARRIERS TO REPORTING <ul><li>Not considering the event as related to immunization </li></ul><ul><li>Not knowing about reporting system and process </li></ul><ul><li>Lethargy - procrastination, lack of interest or time, inability to find report form </li></ul><ul><li>Fear that the report will lead to personal consequences </li></ul><ul><li>Guilt about having caused harm and being responsible for the event </li></ul><ul><li>Uncertainty about reporting an event when not confident about the diagnosis </li></ul>
    17. 17. <ul><li>How would you encourage the </li></ul><ul><li>Reporting of adverse events following immunization (AEFI) in your State? </li></ul>