The hows and whys are down to the govt to sort out and get them back up again.
Hence the vaccine passports for nightclubs, festivals and possibly universities propaganda.
I think there's less urgency In the younger ones too, they know (or perceive) they're going to be ill for a few days after the vaccines so many do put it off due to social or work commitments, its the same with 2nd vaccines, those who were ill after the 1st are reluctant to book a 2nd if it coincides with a social commitment, busy work schedule or child care arrangements