Have you considered telephoning a furniture store that specializes in leather, or possibly the store where you bought the couch? Or call Sears carpet cleaning department? Or Stanley Steamer or somebody of that nature?
The Vinegar solution will work to disinfect but doesn't always smell great. Apple Cider Vinegar smells better but has a color to it, so I would worry it might discolor if applied directly to a fabric or leather.
The Vodka concoction sounds interesting and in theory the alcohol from the Vodka should act as a disinfectant, and with the other oils should smell fabulous.
I would definitely get yourself some leather conditioner or at least leather conditioning wipes for afterwards, and for general purposes to keep the couch looking fabulous for years to come.
I feel your pain lady. My eldest had a stomach flu for 10 days a few years ago. He always managed to climb into the reclining rocker and throw up there, usually sitting on my lap, of course. It was quite an ordeal to get it cleaned up properly. I found furniture professionals to be very helpful in my research. Good Luck.