T i m wrote

One for the medical people ... As more and more people take
the jab I was wondering if there are any stats that cover what
sort of reaction they may have to one and why that might be?

Its mostly your immune system reacting to the vaccine
when it isnt something more serious like anaphylaxis.

eg. We both had the AZ jab (she's had both now)
and neither of us had any reaction at all.

In contrast, a mate, his Mrs and their friend all had
theirs and all three suffered ranging reactions from
headaches, overall aching to nausea etc?

Same vaccine ?

As I understand it, the vaccine (most vaccines) start building
our own antibodies by exposing them to an inactive version of
the target virus (profile?) in readiness for the real / active virus

More accurately the vaccine gets the immune system to do that.

and it's likely that it's that load on our bodies
that causes some of these reactions?

Not really. Its mostly the immune system reacting to the vaccine.

So assuming it is (and not just an allergic reaction etc) if you don't
have any reaction symptoms at all, could it be you haven't been
given the vaccine (a placebo, I'm not suggesting this likely in this
case), that you already had sufficient antibodies for some reason

Nope, its not that.

(previous similar viral infection or just because) so the body didn't
react ... your body doesn't actually react (create antibodies),

More that it doesn't react as aggressively.

effectively meaning that you are no better protected

That can happen with some people, but is unlikely with you two.

or you just happen to have a different physiology to
those who do seem to have more prominent symptoms,
where the same things are going on re antibody
generation but your body can do it 'easily'?

More that it doesn't react as aggressively to the
vaccine, but still does produce useful antibodys.