Well, let's see. When I was in hospital a few years ago, I met a total of perhaps 15 people during a week. Pinpointing the cause of an infection would have req

Well, let's see. When I was in hospital a few years ago, I met a total of perhaps 15 people during a week. Pinpointing the cause of an infection would have required testing those 15. Also, there's good evidence that the vaccines dampen transmission. Random quote (from Nature): "…people who become infected with the Delta variant are less likely to pass the virus to their close contacts if they have already had a COVID-19 vaccine than if they haven’t1. But that protective effect is relatively small, and…" and basically the effect is small but measurably present.