My understanding is that it's pretty clear that vaccine do not do a good job at preventing infection (i.e. testing positive and/or having cold-like symptoms), Delta or not. I don't think they were ever advertised as such.
The mRNA vaccines were very good at preventing any infection, between 80% and 95% effective depending on variant and study. J&J was between 65 and 80% depending on the variant and study. All of them have been excellent at preventing hospitalization and death.
And they definitely were advertised as helping to prevent the spread. That's the whole "herd immunity" thing. After all, one goal is to prevent the epidemic from hitting the unvaccinated.
Vaccines prevent _diseases_ that can be dangerous, or even deadly. Vaccines greatly reduce the _risk_ of infection by working with the body’s natural defenses to safely develop immunity to disease.
You're speaking nonsense. If you mean the vaccine doesn't prevent a virus particle from going into your body, you are correct. They aid the immune system in fighting the virus once it's inside. "Infection" is usually used when some boundary of viral load is crossed, a boundary almost impossible to reach through any means other than internal incubation. Hence, vaccines prevent infection.
Politicians certainly didn't deliver a great message about it though...when they are the ones that are giving out 99% of the information about the vaccine (since I don't think the drug companies can advertise a non-approved drug). Many vaccines are meant to prevent infection, but this type is meant to mostly reduce the chance of severe infection by training your body to see the virus sooner and know how to attack it with less "training".
That depends on what you mean by "good job". It's certainly better at preventing sever illness than it is at preventing infection altogether, but it's still quite good at that (better than the typical flu vaccine, for instance).
> I don't think they were ever advertised as such.
Correct based on my understanding. But sadly I see people quoting all the time (on social media) that it prevents infection. So there's probably a fair bit of misconception out there
And they definitely were advertised as helping to prevent the spread. That's the whole "herd immunity" thing. After all, one goal is to prevent the epidemic from hitting the unvaccinated.