https://covid.cdc.gov/covid-data-tracker/#vaccinations
When that reaches +80% the recommendations will ease more but as of now:
https://www.cdc.gov/coronavirus/2019-ncov/vaccines/fully-vac...
Right now across US being fully vaccinated is only 80% effective against infection. When you have 20k vaxed folks meet when the virus is endemic in the pop, some of those vaxed folks will be infected and some will catch it there.
When more folks are vaxed there will be less of the virus circulating and then that calculation then changes. It's all about how prevalent the virus is in the community to begin with assuming no strains appear that dramatically reduce the effectiveness of the vax.
https://www.npr.org/sections/health-shots/2021/04/13/9864114...
You and the other commenters arguing your "side" also seem to completely ignore the phenomenom of natural immunity, which I think very obviously has been fallaciously denied by "experts" precisely because they want to convince everyone in the world to get this vaccine. They're already talking about yearly booster shots because most people's mental models are from Flu which has a much greater space of possible genetic configurations, whereas SARS-2 is relatively constrained in how it can evolve and thus should not need a yearly booster if this weren't just about making absurd amounts of money (which it is).
In any case, you should know that there are people like me - very much in the minority - who refuse to submit to such absurdities and will keep fighting. We will continue to be literally as well as metaphorically discriminated against until your "side" stops brainwashing people into a completely disproportionate response to an endemic respiratory virus.
You can stay inside with a mask on while vaccinated all you want. Be my guest. But please stop advocating for and/or supporting mandates and restrictions on the rest of us who have not caught your specific strain of agoraphobia, germaphobia, OCD and misanthropy.
There is no definitive answer whether vaccine will reduce transmission. Those 20,000 people will definitely meet un-vaccinated people in next 10-12 days, and then may pass the disease to them.
Many people cannot get the vaccine, because it is not open yet to them, or have other conditions. So it is selfish for vaccinated people to behave as though the rest of the population does not exist.
There is also the worry that longer the disease lingers anywhere in the world, there can be mutations which are immune to current vaccines, such an mutation could be disastrous as people will loose trust in the vaccine and a second vaccine even when available will have lesser adoption than now . It could become a vicious cycle where there is third mutation, and this then becomes like the flu shots ( but lot more deadlier)