Search for correlates of protection

Abstract

Nowadays a wide variety of vaccines exist to prevent diseases. However, the correlates of protection in immunisation are an unresolved issue. This hinders the development of new vaccines and improvement of current vaccines. To measure the efficacy of newly developed vaccines, several methods can be used, such as determining the antibody titer, measure the CTL activity and determine the cytokine production. However, all of these methods have their limitations. The antibody titer does not correlate to the efficacy of the vaccine. Moreover, titers can be measured in various ways, making them incomparable. Also, only the humoral response is measured. This makes it limited to asses the complete protection. To indicating the strength of the cellular response, CTL activity can be determined. This is however, an inconvenient method to use and contradicting results were found in human studies when correlating it to the efficacy of vaccines. The role of cytokines during an immune response is still not clear and therefore would not be a good parameter to determine the efficacy. Another aspect with regard to immunisation, are the influence of factors such as age, route of delivery and lifestyle. There exact influence, however, needs to be determined yet. Therefore, more research is necessary to determine the specificity of parameters and the affecting factors. Identifying the optimal correlates of protection per vaccine is recommended. This would be easier if the different methods were optimised and standardised. Using several methods will extract the mechanism behind immunisation, making it easier to develop new vaccines.