FWIW:
[quote]
The CDC reported 6,587 COVID-19 breakthrough cases as of July 26, including 6,239 hospitalizations and 1,263 deaths. At that time, more than 163 million people in the United States were fully vaccinated against COVID-19.
Divide those severe breakthrough cases by the total fully vaccinated population for the result: less than 0.004% of fully vaccinated people had a breakthrough case that led to hospitalization and less than 0.001% of fully vaccinated people died from a breakthrough COVID-19 case.
Most of the breakthrough cases — about 74% — occurred among adults 65 or older. [\quote]
Source