Tell us how you plan to manage vaccination status amongst members and visitors. Based on your feedback we will introduce a method that works for as many clubs as possible.
For example, you can use a custom field in the member record to indicate vaccination status and we will add a plugin that validates bookings for all guests in the booking. This will work best for clubs with Configuration Item TARIFF_BY_MEMBER set to YES, because each family member has their own database record in this configuration. The plugin will show an error message with the names of unvaccinated persons and the booking will not proceed. You can turn plugins on and off via admin menu → Site Config → Plugins.
For visitors, you will need to ask for evidence of vaccination, e.g. an emailed certificate. You can record this in the admin comments section of a booking. If you decide to hold all bookings as TENTATIVE until vaccination status is shown, we can arrange that as well.
Let us know if this would suit your needs or if you have other ideas.