The current mRNA vaccines were built on spike proteins common to COVID. There was enough data to establish their efficacy and effectiveness. The efficacy data is impressive and better than anyone could’ve imagined. I got mine on 12/24 and get the second dose on Thursday. More importantly, my early-70s parents got their first doses last week. Things should hopefully be close to normal by August/September if enough people get vaccinated.
There are still a lot of questions to be answered before that will happen. The CDC says that the vaccine "should" prevent people from catching the virus after they are immunized and the immune system has a chance to build up. But they are still saying that they do not know for sure if it will actually prevent somebody from getting it. As far as anybody up the chain will say is that it "should" at the very least make catching the virus less severe. The current statements are that even after your second dose that you should still wear a mask because you could still catch it and then become an asymptomatic spreader.
In theory, about a few days after your second shot, almost everybody should have a good degree of immunity to the virus. The issue right now with a lot of people catching it for the second time, nobody knows how long overall immunity will last and nobody wants to subject themselves to litigation. What I would love to see is a mid-sized community (50K people or so) and immunize everybody possible. Then after a month, start keeping tabs on viral spread. If for example, they would pick a city that had a decent amount of covid cases, but not one that had been hammered by it. Then starting after everybody had the vaccine, look around at numbers of new cases just from that city. See if the total number of infections goes down (it should). It would go a long way in establishing expectations. It theory, it should have a very drastic impact. I'm not saying we shouldn't continue to focus on the people that are being focused on. But as a side project, try to hit one specific area hard over a few days to see what happens.