Do I have to fast before my blood tests?

For the tests aiming on direct pathogen detection (PCRs, qPCRs, FISH) or pathogen-related serology, no need for fasting. 

For immune-related tests (cytokines, inflammatory markers, etc), the fasting is not mandatory but the test cannot be performed on lipemic or hemolytic samples. Thus 8h fasting or very light meal without fat before the blood draw is recommended.