I don't think you quite understand what science is. In medicine we have a hierarchy of what counts as scientific evidence. Expert opinion/experience is the bottom of that triangle. So, yes, anecdotal evidence can be science. In medicine we call it a case study.

The top is metanalysis of multiple randomized double blind trials that don't have conflicts of interest. There are now multiple studies that support DSK's point that people who are "up to date" on their covid vax are more likely to get covid and get sicker with it than those who are unvaxed or "not up to date".