Dear User,
“The vaccine certainly does not save lives” and “it lessens the severity of the disease” seems like a contradiction. Or a mistype. As an aside, the partial immune response initiated by the vaccine, is the same molecular compound and just as natural as the immune response of an actual infection. Though it is believed to be less robust.
It is not obvious that antibodies alone protect from reinfection. Previous exposures usually give the immune systems much more tools than just antibodies. Experiments conducted last year demonstrated the ability to repeatedly effect the body with covid. Admittedly, this was a lab experiment and is very difficult for it to occur through regular human interaction.
But this discussion is for when this will become just another endemic disease. Until them it is all about slowing or stopping the thread.