Study of Vaccine safety
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The document outlines the history and mechanisms of vaccine development, safety monitoring, and the regulatory framework surrounding vaccines, including notable incidents and acts aimed at improving vaccine safety. It discusses the importance of rigorous pre- and post-licensure studies and the role of surveillance systems in detecting adverse effects. Additionally, it highlights the challenges in assessing vaccine-related adverse events and emphasizes the responsibility of immunization providers in ensuring vaccine safety.
Study of Vaccine safety
- 2. • First vaccine was developed by “Edward Jenner” in 1796 for Smallpox. 1. Cutter incident – 1955 (Polio virus) 2. Simian virus 40(SV 40)- 1955-1963 3. HPV Vaccine Recall- 2013 • In the mid- 1970 several lawsuits were filed against vaccine manufacturers and healthcare providers • National Childhood Vaccine injury Act(NCVIA) IN 1986 By the CDC(01/07/1946) • Global Advisory Committee on Vaccine Safety (GACVS) in 1999 By WHO. • In india”Indian Council of Medical Research”(ICMR)
- 3. Introduction A vaccine is a biological preparation that improves immunity to a particular Disease. Vaccine are among the most cost-effective and prevalent public health interventions. Morbidity and Mortality declined where immunizations are practiced. Vaccine safety prime for: -Public -Manufacture -Immunization Providers -Recipients of Vaccine No vaccine is completely safe or completely effective, while all known vaccine adverse events are minor and self limited, some vaccine have been associated with rare but serious health effects.
- 4. Vaccine ADR Knowledge and research capacity has been limited due to: - Inadequate Understanding of biological mechanism of underlying ADR - Insufficient information from case reports & case series. - Limitation of existing surveillance systems to provide evidence of causation. To overcome these limitations: Epidemiology
- 5. Importance of Vaccine Safety • Decreases in disease risks and increased attention on vaccine risks • People’s consideration about vaccine is – Higher standard of safety . – Vaccines generally healthy . – Lower risk tolerance = need to search for rare reactions. – Vaccinations universally recommended or mandated.
- 6. Methods of monitoring vaccine safety • There are two methods of monitoring vaccine safety. 1. Pre-licensure 2. Post-licensure
- 7. • Vaccines like other pharmaceutical products, undergo extensive safety and efficacy evaluation in the laborartory. • Pre-Licensure studies are carried out on: Animals Humans
- 8. • Phases I, II, II trials • Common reactions are identified • Vaccines are tested in thousands of people before being licensed and on the market allowed • Poorly detected reactions: – Rare – Delayed onset – Subpopulations
- 11. • Identify rare reactions • Monitor increases in known reactions • Identify risk factors for reactions • Identify vaccine lots with increased rates of reactions • Identify signals Phase-4 studies can be an FDA requirement for licensure. These trial include tens of thousand of volunteers and may address question of long-term effectiveness and safety or examined unanswered questions identified in Phase-3 trials. Manufacturers must submit samples of each vaccine lot and results of their own tests for potency and purity to the FDA before releasing them for public use
- 12. • Vaccine-induced • Vaccine-potentiated • Programmatic error • Coincidental
- 13. 1.Vaccine induced: Due to intrinsic characteristics of the vaccine preparation & individual response of the vaccine, these events would not have occurred without vaccination E.g. Vaccine associated paralytic poliomyelitis after oral polio vaccine. 2. Vaccine-potentiated would occurred anyway, but precipitated by the vaccination. E.g. First febrile seizure in predisposed child. 3. Programmatic error Due to technical errors in vaccine preparation handling or administration 4. Coincidental Associated temporally with vaccination by chance or due to underlying illness.
- 15. 1) SIGNAL DETECTION • Surveillance systems help in detecting the adverse events of vaccines in timely manner. • Vaccine safety Surveillance system should examine multiple exposures and multiple disease outcome • The sensitivity and specificity depends on the goal of surveillance. • Sensitivity- detection of a previously unknown illness or syndrome • Specificity- tracking a known disease
- 16. 2) ASSESSMENT OF CAUSALITY: Assessment of vaccine associated adverse events is not possible unless … o A vaccine specific clinical syndrome is observed o Recurrence upon re-challenge. o Vaccine specific laboratory finding • Epidemiologic studies are necessary to assess whether vaccinated persons are at higher risk than unvaccinated persons if adverse event occur in absence of vaccination.
- 17. 3) EXPOSURE • Documentation of exposure status is important to prevent misclassification • Poor documentation due to o Substantial mobility between health care providers o Substantial difficulty may be encountered in ascertaining vaccination status- In older persons • Immunization card recorder
- 18. 4) OUTCOME • EVENTS being assessed are frequently extremely rare. (e.g. Encephalopathy, GBS) • Many adverse events caused by vaccines are poorly defined clinical syndromes.(e.g. Encephalopathy, GBS) • The other difficulty in assessing the rare events in populations less frequently exposed is inadequate study power.
- 19. 6) ANALYSIS, CONFOUNDING AND BIAS: • Since vaccines can lead to series of outcome, cohort studies can be considered. • In this adverse events & person-time risks are evaluated. • When outcomes are rare, these studies become time consuming and expensive. • Case control studies are also carried out in case of rare adverse effects.
- 20. • In 1990 CDC established the Vaccine safety Data-link project to improve scientific understanding of vaccine safety. • This project involves partnership with 10 large managed care organizations (MCOs) to monitor vaccine safety. • Each participating organization gathers data on vaccination (vaccine type, date of vaccination) medical outcomes(outpatients visits, inpatients visits, urgent care visits), birth data and census data. • In 2005, Rapid Cycle Analysis(RCA) project by VSD • RCA to monitor adverse events following vaccination in near real time, so the public can be informed quickly of possible risk.
- 21. • It is National reporting system & Jointly administered by CDC and FDA • VAERS was created in 1990 to unify the collection of all reports of adverse events after vaccination • Passive reporting system(depends on health care providers, vaccine manufacturers and genral public) • Detects – new or rare events – increases in rates of known events – patient risk factors
- 23. • VAERS (U.S.A.) • MSAEFI (CDC), U.S.A. • VAAE (CANADA) • IMPACT (CANADA) • YELLOW CARD REPORTING SYSTEM (U.K.) • BCDSP (U.S.A.) • ABERDEEN DUNDEE MONITORING SYSTEM (SCOTLAND) • PRESCRIPTION EVENT MONITORING (DSRU, SOUTHAMPTON, U.K. ) • ICMR (INDIA) • UPPSALA (SWEDEN)
- 24. Immunization provider, also play a key role in helping to ensure the safety and efficacy of vaccines through proper: Vaccine storage and handling Vaccine administration Timing and spacing of vaccine doses Observation of precautions and contraindications Management of vaccine side effects Reporting of suspected side effects Communication about vaccine benefits and risks