Here's a reassuring article on breakthrough cases in Utah that includes references to recent studies done elsewhere on breakthrough cases, and why "breakthrough" is a bit of a misnomer:https://www.sltrib.com/news/2021/07/16/andy-larsen-breakthroughSome excerpts:"The abundance of mild cases among the fully vaccinated has led some scientists to argue that we should redefine “breakthrough” cases. Their point is that some large percentage of these positive tests are actually only infecting people in their upper respiratory tract, where the primary immune system that reigns is mucosal immunity, not the blood-based immunity that the vaccines create. In other words, it’s not that these infections are “breaking through” the protection built by the vaccine, they just never reach it at all. It’s an interesting argument."The study:https://www.jci.org/articles/view/151186Another excerpt from the above article regarding a recent study of breakthrough cases in Israel:Avg age of hospitalized breakthroughs in Israel = 71. Most had preexisting comorbidities."...it’s generally those who were at highest risk of hospitalization before who need to worry most about breakthrough infections.To wit, in the Israel study, there were six people who were hospitalized with breakthrough infections of COVID-19 without comorbidities, and all six have had what the study called “good outcomes.”