Strangles vaccine side effects?

I just gave my horse his strangles vaccine yesterday, I wasn't sure if he had ever had it because the previous owner never gave it to him but she didn't know if the people she bought him from had. So to be safe I followed the instructions for vaccinating for the first time and gave him 1ml in the neck. What are the side effects of this vaccine? He is not swollen at all, he is a little lethargic but he was acting really different from normal i.e. breathing kinda hard and being a LOT friendlier than he usually is. I can tell he's a little sore, he didn't wanna put his neck down to graze so I just hand fed him... Is this all normal and how long will it last?