I disagree with your doc. It appears that it is likely life long immunity in the T cells. If it were waning immunity in four months we would be seeing a boatload of reinfections. We are not.
That is my thought also.
I was exposed (as in very close exposure) in March, and had no symptoms other than having to spend a days working from home.
Doc is a very cautious person, and is worried I will start believing I am superman and rolling in covid patients (volunteering at church). Which I have given her every reason to suspect.
Kind of sad about ivermectin. Used to give it to horses. Ate a bit of the paste as a kid since Dad said it tasted like apple.
It did not. Dad was not amused