@samohTmaS
"Based on the 54% effectiveness reported for JN.1 at 2 months, a shot a month should about do it, provided FDA and CDC would allow it. "
Apart from a probably increasing vaccination risk, would there even be a new vaccine (variant) every month?
If your probability holds true, 54% at 2 months, 30% after 9 months is astonishingly good still.