The request by authorities to remove thiomersal caused fear amongst the general public concerning the toxicity of vaccine components, and negatively impacted overall vaccine uptake and acceptance. In the subsequent years, following authority guidance, vaccine manufacturers have removed thiomersal from most paediatric vaccines and reduced the amount of thiomersal in the few remaining vaccine formulations in a common effort to remove mercury from vaccines and re-establish public confidence in immunisation programmes. However, the WHO acknowledges that making changes to the thiomersal content of licensed

vaccines containing this preservative is a complex issue requiring careful consideration. Any change in the formulation of thiomersal-containing vaccines may

LDK378 in vivo have an important impact on the quality, safety and efficacy of the vaccine Selleckchem PCI-32765 and therefore any decision regarding the elimination or reduction of thiomersal in vaccines should be based on a demonstrated adverse effect. New-generation vaccines are subject to increased safety testing throughout the vaccine development process. The safety assessment has been enhanced throughout preclinical, clinical and post-licensure studies. All safety assessments performed have the objective of increasing the likelihood of identifying possible safety concerns and consequently of taking the necessary measures to remove or minimise them. Available data indicate that licensed vaccines have a benefit–risk profile where the benefits clearly surpass the risks. This short overview of vaccine development processes and post-licensure surveillance describes how clinical development and assessment of vaccines is constantly improving and evolving. It also illustrates else how changes to the processes over time have helped to

generate the robust data needed to enhance the benefit–risk profiles of new vaccines. There is now a large number of diseases for which licensed vaccines are available (Appendices, Supplementary Table 6), however, we are still faced with challenges in the form of diverse populations and complex pathogens; these require further novel approaches to antigen selection, manufacture, presentation and delivery. The main areas of new vaccine research are the subject of Chapter 6 – Vaccines of the future. “
“Key concepts ■ New tools are available to aid vaccine manufacturers in meeting challenges for new vaccine development □ Many technologies that are already available continue to be improved, including adjuvants and novel vaccine delivery platforms The advances made in vaccine technology since Edward Jenner vaccinated the young James Phipps against smallpox have had a spectacular impact on human health over the last two centuries (see Chapter 1 – Vaccine evolution).