Innate immune responses are mediated by several types of immune cells, and the first aim of the project was to identify precisely which of these immune cells can be activated by the vaccines, and could be thus good candidates for increased function by the future vaccines. We have identified several of the innate immune populations from the blood which can be very effectively activated by certain types of vaccines, and also the mechanisms through which this activation takes place. In addition to that, in additional studies we have investigated whether the time of the day and the season of vaccination is also important for these effects. Indeed, this seems to be the case, fact that has important consequences for the public health measures necessary during vaccination campaigns.
In additional studies, we have also investigated the importance of the diet and lifestyle of the volunteers for the induction of immune cell activation. We have observed that unhealthy lifestyles lead to immune cells that are continuously inappropriately activated, and that can induce on the one hand inflammatory diseases, but on the other hand can reduce the effectiveness of vaccination. These data underline the importance of a balanced diet and a healthy lifestyle.
Finally, we have used this information and designed clinical trials in which vaccines that activate innate immune cells are tested for their capacity to protect elderly individuals against infections. In one such trial performed just before the COVID-19 pandemic, the BCG vaccine (that is usually used against tuberculosis) has been shown to decrease also the prevalence of other infections by 40%. Subsequently, similar studies have been designed and performed during the COVID-19 pandemic, with the results showing that while the total number of COVID-19 infections was not modified, the severity of the infection and the mortality was decreased by BCG vaccination.
