All due sympathy to your family member, but there is potential for serious side-effects in almost every medical intervention. It's true that these vaccines received emergency authorization, so the known unknowns are greater in number than usual, but this vaccine appears to be safer than many commonly prescribed medications. It's as irrational to be anti-vax as it is to be anti-medications. First do no harm does not imply a guarantee against all potential harm in all cases for all people (the world is too complicated to guarantee such a thing).

(I do think Western medicine is slavishly focused on medications and relatively blind to prevention but that's a separate issue)