Those two sentences are equivalent, not contradictory. We commonly say that condoms prevent pregnancy and STD's, but they're not perfect either.

If the vaccine prevents one case of spread while not preventing another, it has still prevented COVID spread.

"Not perfect" and "has a small impact" aren't the same. If condoms had the same failure rate in preventing STDs/pregnancy as the COVID vaccines do for preventing infection, we wouldn't use them. Luckily, preventing infection isn't the only goal of vaccines, so it's still worth getting for the protection from severe illness and death.

> If condoms had the same failure rate in preventing STDs/pregnancy as the COVID vaccines do for preventing infection, we wouldn't use them.

No? If they were the best form of contraception we had (which is the relevant comparison w.r.t. vaccines), of course people would use them! It would make abstinence marginally more appealing, of course, but there are already people who don't want or can't afford a pregnancy who unwisely choose to forgo contraception. There would certainly be an enormous number of people who would choose to use condoms rather than forgo sex entirely.

If vaccination prevents you from catching covid, then it has prevented you from spreading covid to those you would have otherwise.

If vaccination causes you to experience an early immune response, versus several asymptomatic days while unknowingly contagious, then it has prevented you from spreading covid to some of those you would have otherwise.

If vaccination results in a less severe infection with lower viral load, then it has prevented you from spreading covid to some of those you would have otherwise.

My reply was intentionally simple in order to drive home a point about selfish versus societal viewpoints.

> If vaccination prevents you from catching covid, then it has prevented you from spreading covid to those you would have otherwise.

Depends on what you mean by "covid" here. If you're referring to the virus, then no - this is a misconception. The vaccines at best only reduce symptoms, they don't stop infection or transmission.

> versus several asymptomatic days while unknowingly contagious

This was also an early guess that turned out to be wrong. We've known this wasn't a thing for years, at least before these vaccines.

> My reply was intentionally simple in order to drive home a point about selfish versus societal viewpoints.

Right now, getting vaccinated is the selfish action because it's likely to turn you into an asymptomatic spreader. At least when unvaccinated you'll know to stay home.

> Right now, getting vaccinated is the selfish action because it's likely to turn you into an asymptomatic spreader. At least when unvaccinated you'll know to stay home.

This is a) insane and b) directly contradicts the point you tried to make above it.

How does it contradict it? These vaccines reduce symptoms without stopping infection/transmission -> you're helping yourself without helping the community -> it's the selfish action.

You can't argue asymptomatic spread isn't a thing, and then claim the vaccines are bad because they cause asymptomatic spread.

> > We've known this wasn't a thing for years, at least before these vaccines.

If I remember the timeline right it was mid/late 2020 we realized that assumption was wrong, then about a year later it was apparent the vaccines weren't stopping the spread. So yeah, my statements are entirely consistent: There wasn't before the vaccines, there was after.