On Vaccine side effects.
Biology is a very slippery science.
The people that get significant side effects in trials and then are revealed to be in the placebo group for one.
Its not like something solid like Physics would have so much uncertainty :-)
Everyone is different, some get less to none, but immune system is still doing its thing just as effectively.
Its like people who never seem to get a cold, but maybe they do and don't pay it any attention.
Main reason I think for discouraging the idea of a reaction being immune system doing its thing is...
Well the large number of people who will worry their shot failed if they don't feel anything.
YMMV , Yeh Biology