I've always had flu jab (free from work) and never had the flu either?
. So guess throw ya dice take your chances. (Polio, measles and so on)
As for the vaccine changing DNA, erm that not how they works. RNA in some form that get "ran" by the cell to produce protein spikes for the body to make antibodies to. Or others are a disabled version of the virus which still creates an antibody response which is still just RNA. (There are other vaccine methods too)
You might mean crispr which is a way of editing dna, but that would fail safely tests and be very evident. The vaccines are gonna be extra scrutinised, it also wouldn't generate an antibody response afaik. Also they said even oxford one wont be available next year as the larger trials for safety testing will take at least that long.
Oxygen is actually toxic at certain partial pressures. I'm more worried about the microchips that can fit down the bore of a needle and control people #starTrekIsntReality. ?
Happy Friday ?
Edit: ps it won't be mandatory we gonna march you to your docs and force you to have it. Well except maybe in China ?
Pps: as much social contact as possible? Lol, troll fridays?