 Symptomatic samples will be analyzed by means of multiplex polymerase chain reaction PCR. In addition, the investigators will assess microbial compositions based on next generation sequencing and apply multiplex panels to study parameters of unspecific humoral immune response. The study will allow to assess homologous and heterologous effects of infections and vaccinations measuring specific humoral immune response. In collaboration with immunologists, immune phenotypes will be studied and functional tests will be conducted. 