Sambucol is elderberry extract. You can buy it online or at any health food store. It's in a bottle like cough syrup. There is nothing in it but the elderberry extract and sweetener, I think. No alcohol.
It has been proven as effective as Tamiflu in some clinical studies. It's made in Israel.
We have experimented with it all winter now. When there is a virus in the house, we take one dose (for adults, 2 tbsp) a day. When you yourself feel the first symptom of a cold, up that to 3x a day. It seems to make the cold either not show up, or show up so mild it's amazing. That is happening to me right now.
Instead of going through 2 Kleenex boxes as usual, I have used maybe 6 total Kleenexes. That means less problems with coughing later on. I don't think I have coughed at all.
I was doubtful of the antiviral properties but it seems to be working for me and my kids.