Viibryd is pretty new to the market and is supposed to work faster then the current AD meds but there is not a lot of info out on that yet. I would call your pharmacist and ask them for info re this new drug. Viibryd is a selective serotonin reuptake inhibitor (SSRI) and a 5-HT1A receptor partial agonist. I believe it hit the market the last half of 2011.
https://www.hightable.com/mood-disorders/insight/viibryd-approved-by-the-fda-52518