the problem with this approach though is that even places with over 90% vaccination rates have COVID outbreaks. For example, Cornell University, which has a 97% vaccination rate, recently had an outbreak of COVID. I also read of a cruise ship - everyone on board over 12 was fully vaccinated, yet there was an outbreak on board.

So I'm not sure a vaccine passport would actually protect people. Social distancing, quarantining people who get COVID, contact tracing and follow up - all of these were proven effective for containing outbreaks in places like S. Korea.