Theoretically yes. But we still do not know for how long just one dose can be effective (or TWO for that matter! and when we need dose #3) — because the vaccines have barely been out or tested...and the “3 week” period between the two doses had more to do with rushing their emergency authorization trials than it did with any major scientific necessity.
Even what you say doesn’t change the fact that the scheduling of a booster and dosages should be adjusted by age, risk, and prior infection. And that there could be more harm than good done by over-immunizing.
“Theoretically yes. But we still do not know for how long just one dose can be effective”
Correct. There hasn’t been enough time to know for sure, but there is good evidence. Dose one of Pfizer and Moderna produce antibodies, but don’t produce many Memory B Cells.
Without the Memory B Cells being triggered there is no way for the immune system to grant long term protection.
Unfortunately to trigger the Memory B Cells a second dose needs to be delivered with 1 to 6 months. If we wait a year to see how the vaccines hold up, we are right back to most of the population having no immunity.