... Viruses mutate. This virus will always be around even if it lies dormant for years. 1
... Not just one dose, but two doses are needed 2. Now they are going to go door to door??
There is a reason they want everyone vaccinated, and I find it very hard to believe it's to prevent the spread. There is a far greater and IMO more devious reason. 3
1 Each "variant" is a mutation that has to some degree spread at least regionally. All three vaccines authorized for use in the US is known to be effective against every one of those mutations. To date it is not known how long immunity from vaccination lasts, because they have been under test since spring 2020 (Pfizer and Moderna) and "all" that is known from those tested earliest is that they still have effective levels of antibodies,
and the vaccines have triggered appropriate T- and B-cell responses (the immune system's long-term memory).
2 Two-dose vaccines are not unusual. For example, the Shingrix vaccine is also a two-dose vaccine.
3 Seriously? What is that "more devious reason"?

As to whether the vaccines in use in the US "prevent the spread", this webpage has graphs of daily new cases and daily deaths,
https://www.worldometers.info/coronavirus/country/us/ . US daily news cases and daily deaths have plummeted and plateaued to a low level, starting in mid January, a month after vaccination began in the US. Compare those graphs to the corresponding graphs for our neighbor Canada ,
https://www.worldometers.info/coronavirus/country/canada/ , which did not start getting serious about vaccinations until late February and early March. I think the data evidences that vaccines in the US have "prevented the spread".