This post doesn't seem to be about influenza at all except to diss flu vaccine. As for the effectiveness there's this from 2009 which has pointers to quite a bi

This post doesn't seem to be about influenza at all except to diss flu vaccine. As for the effectiveness there's this from 2009 which has pointers to quite a bit of evidence. https://pmc.ncbi.nlm.nih.gov/articles/PMC4504386/#bib31 https://pmc.ncbi.nlm.nih.gov/articles/PMC4504386/#bib31 "Estimates of vaccine effectiveness—the prevention of laboratory-confirmed influenza illness in vaccinated populations—vary from less than 50% in years with poorly matched vaccines to 50% to 90% in years with well-matched vaccines." The poster isn't likely to like the other recommendations of what do in the face of an influenza pandemic if no effective vaccines are available but they'll be familiar. It's hand-washing, wearing a mask, and if it's really bad shutting down schools and avoiding public gatherings.