AFAIK, the flu vaccine doesn't prevent against all strains, because the virus mutates so rapidly year by year. They prepare it every year based on the worst/mos

AFAIK, the flu vaccine doesn't prevent against all strains, because the virus mutates so rapidly year by year. They prepare it every year based on the worst/most common strains that were seen in opposite hemisphere's flu season. It does help limit the spread though, and is still really important to get.