All adults who have been fully-vaccinated will no longer have to self-isolate if they are identified as close contacts of someone with coronavirus from 7 August.
Children and young people under 18 will also be exempt from the need to self-isolate if they are also identified as close contacts of a positive case. But everyone who tests positive for coronavirus or has symptoms must continue to isolate for 10 days, whether they have been vaccinated or not.
https://gov.wales/changes-self-isolation-fully-vaccinated-adults