In the UK the COVID vaccine was offered nationally through a government site but you could get it sooner and closer through local GPs. They could stop once they had covered the old and vulnerable though. In my area, they carried on for a while but only if you requested an appointment in the comments of a private Facebook group.
I wasn't thrilled by the delay, but also thought the assumption of vaccine hesitancy from others in the meantime and hard to navigate process could put some off entirely.
Yes, I saw Facebook being a gateway (and a potential roadblock) to requesting vaccines from some US pharmacies last year as well. You had to post in the comments to reserve one or make an appointment.
I wasn't thrilled by the delay, but also thought the assumption of vaccine hesitancy from others in the meantime and hard to navigate process could put some off entirely.
But for everyone else, what a sign-up incentive!