No, they aren't effective in reducing spread. Singapore, Israel, UK, Wisconsin studies or even just public data on US infections all tell the same picture.
See, you quoted a couple of sentences of an article literally titled "COVID vaccines cut the risk of transmitting Delta — but not for long" and subtitled "People who receive two COVID-19 jabs and later contract the Delta variant are less likely to infect their close contacts than are unvaccinated people with Delta." and then used it to imply that COVID vaccines don't cut the risk of transmitting the delta variant. That's a classic denier move.
Yes, vaccine-induced protection against transmitting the delta variant may be limited; no, that doesn't mean it's nonexistent.
There are other studies too, like [1].
Finally, the site guidelines explicitly ask you not to say things like "looks like you didn't read the article you submitted".
