A placebo has no physical or physiological effect at all, it can only affect what the test subjects think or pretend they feel.

you dont get antibodies against viruses just by thinking you have them.

Even if this is obviously true, that does nothing to support the original statement. That's a whole different claim that you had to fall back to.

Which is a motte-and-bailey type of argument.

if the placebo effect only works for a minority of ailments then its probably something else like you know, regression to the mean

And yet such thinking can in some cases increase your chances of surviving the viral infection. That's the placebo effect.

where did you see something like that?