Excellent combination, CosmicLion!
I can confidently add to this list two more ingredients that are well-known immunity boosters:
1. Sideritis scardica - either extract or the actual herb, made into tea.
2. Garlic concentrated extract - better take it in capsules to eliminate the bad breath. Garlic has been used way back since Ancient Egypt as a treatment to many, many diseases and infections, and is an excellent immune booster.
But most of all, I recommend sleep. Good, healthy sleep between 7 and 9 hours daily is what your immune system needs to be functioning properly.
I will add any other things I can think of to this reply.
Thanks for the topic, CL!