> implies preventing infection and thus spread
@strypey A vaccine works if it has effect and there's a point in taking it.
Flu vaccines have been said to work for decades, even though it's well known that they're anywhere from 20% to 80% effective against recorded infection depending on season and vaccine, because vaccinating the most sensitive members of society reduces suffering and death among those vaccinated, and vaccinating people who can probably get away with a few days of symptoms maintains productivity and reduces spread to those who would suffer worse.
The idea that a vaccine doesn't work if someone got vaccinated and later was infected anyway is a misinformation campaign directed against sensible public health policy and I am sad to see it repeated here.