“Breakthrough” and “full-blown covid” imply that they got severely sick, hospitalized or put on ventilators.
"Breakthrough" absolutely doesn't imply they got severely sick. If you read the article in the previous post, the patients mentioned were asymptomatic. And people who have been vaccinated can still get Covid, but generally, their cases should be mild to moderate at worst.
Yes, "full blown" implies a different situation, but I think the reference by a previous poster that there were 3 "full blown" cases was not supported by the later developed facts.