The Travel Doctor (a chain of clinics that does vaccination for travellers) claims
Can I drink alcohol after vaccines?
[Don't drink too much after Japanese Encephalitis vaccine]
The myth about "no alcohol after receiving vaccines" may have begun this way... Apparently army recruits used to be given numerous vaccines and then be given a day off to recover...and what did the army recruits do when they had the day off? They went to the pub and got drunk and obnoxious, so the army advised them not to drink any alcohol for 48 hours after their vaccines.
Did the military start the "no alcohol after receiving vaccines" meme?