Just seen a study showing that, with the AstraZeneca vaccine, protection wanes so much after 3 months that there's virtually no reduction of transmission as far as the Delta variant is concerned vs an unvaccinated person so perhaps that's also playing a part given that Delta is now the dominant variant.
Yes, although vaccination doesn't reduce transmission. It still does a really good job at preventing hospitalisation and deaths. This is why case rate doesn't tell the story of how well an area is doing. Better looking at hospitalisation rates which is still many times lower than previous waves. Full vaccination followed by natural exposure is still considered to give maximum long term protection.