IIRC, the protocols for the HepB vax study included active monitoring for 4-5 days (a daily visit to or from a researcher) after every shot to proactively identify short term post injection events, as well as continuous passive monitoring, and final follow-up 3 months after the last vaccine dose which again IIRC was after the 4 month dose, ie at 7 months.
As you point out, a study of 3 doses of a vaccine over several months cannot possibly have only 5 days follow-up.
IIRC, the protocols for the HepB vax study included active monitoring for 4-5 days (a daily visit to or from a researcher) after every shot to proactively identify short term post injection events, as well as continuous passive monitoring, and final follow-up 3 months after the last vaccine dose which again IIRC was after the 4 month dose, ie at 7 months.
As you point out, a study of 3 doses of a vaccine over several months cannot possibly have only 5 days follow-up.