The 15 minute wait is the standard practice for ALL vaccines, not just this one. There are some who experience allergic reactions to vaccines, but it isn’t particularly common. Still, to be safe, your medical provider will typically not let you leave immediately after a vaccination.
I got a Flu shot back in September for the first time since I was in The Marines back in the 70’s. I got the shot and went right to my car and drove to work.......................