At the lefthand side, we have about 3 cases per 100k among the vaccinated and 9 among the unvaccinated, a ratio of 3:1. That’s a surprisingly small ratio.
The San Diego ratio is presumably “surprisingly small” because they’re doing the dumb thing where they compare the “fully vaccinated” (defined as anyone who has had all doses of their vaccine for >=14 days) with the “not fully vaccinated” (defined as the remainder of the population, i.e. no vaccine, or partly vaccinated for any vaccine that gets multiple doses, or fully vaccinated but <14 days since final dose). Since those categories don’t cleanly carve reality at its joints, the resulting 3:1 ratio isn’t particularly meaningful without doing more math.
I don’t know to which extent that problem affects the conclusions in the rest of that section, though.
The San Diego ratio is presumably “surprisingly small” because they’re doing the dumb thing where they compare the “fully vaccinated” (defined as anyone who has had all doses of their vaccine for >=14 days) with the “not fully vaccinated” (defined as the remainder of the population, i.e. no vaccine, or partly vaccinated for any vaccine that gets multiple doses, or fully vaccinated but <14 days since final dose). Since those categories don’t cleanly carve reality at its joints, the resulting 3:1 ratio isn’t particularly meaningful without doing more math.
I don’t know to which extent that problem affects the conclusions in the rest of that section, though.