https://www.nytimes.com/2021/02/23/opinion/covid-vaccines-tr... "Many scientists are reluctant to say with certainty that the vaccines prevent transmission of the virus from one person to another. [. . .] There should be more data within the next couple of months. Until then, precautionary measures like masking and distancing in the presence of unvaccinated people will remain important."

FWIW, it seems like those commentators who were actually right until Delta emerged. Looking at graph of Covid cases in the USA for example we were on track to low case levels until July, then the Delta variant began to break through in vaccinated individuals and the epidemic grew in size again.

Gotta compare 2021 to the the curves from 2020 though: It's the same shape with different magnitude. Looks more like that drop in the spring and early summer was because it's seasonal than anything else, which we misattributed to the vaccines.