When we got our day four tests last month on Anegada we went with a group that had three kids (we rode in an open bed truck so there was little risk of spread).

They are doing day four testing on ferry days at the Anegada clinic.

Last month, of course, there was no distinction between vaccinated or non-vaccinated so it is possible that it has changed.

We were staying on the island as were all the other people we talked with about testing - I don't know if they are treating visiting yachtspeople differently when it comes to testing.