He does have proof of that. It’s called years of understanding of immunology. There is scant evidence of reinfection. Mostly from China. You want to believe that have at it
You are making your post up de novo.
There is no FULL knowlege of SARS_CoV-2 on the human
immune system(s) but it is growing quickly.
There is evidence of reinfections, and it is early.
Want more proof? Coronavirus account for 7 to 30%
of colds. You got them more than once already.