It's obviously a single, unique occurrence, but the CDC's data from the Provincetown situation is sort of interesting:
https://www.cdc.gov/mmwr/volumes/70/wr/m...mm7031e2_w
Some tidbits:
- "469 cases of COVID-19 associated with ... large public gatherings in a town in Barnstable County, Massachusetts, were identified among Massachusetts residents"
- "[V]accination coverage among eligible Massachusetts residents was 69%"
- "Approximately three quarters (346; 74%) of cases occurred in fully vaccinated persons." [The remaining 26% included unvaccinated persons, persons whose vaccination status is unknown, and persons "not fully vaccinated." "Fully vaccinated" was defined "≥14 days after completion of state immunization registry–documented COVID-19 vaccination."]
- "274 (79%) vaccinated patients with breakthrough infection were symptomatic."
- "Among five COVID-19 patients who were hospitalized, four were fully vaccinated; no deaths were reported."
- "One hospitalized patient (age range = 50–59 years) was not vaccinated and had multiple underlying medical conditions. Four additional, fully vaccinated patients aged 20–70 years were also hospitalized, two of whom had underlying medical conditions."
- "There was no significant difference between the Ct values of samples collected from breakthrough cases and the other cases. This might mean that the viral load of vaccinated and unvaccinated persons infected with SARS-CoV-2 is also similar. However, microbiological studies are required to confirm these findings."
Be mindful of the caveats contained in the report, most notably (to me, at least) that "data from this report are insufficient to draw conclusions about the effectiveness of COVID-19 vaccines against SARS-CoV-2, including the Delta variant, during this outbreak." But still interesting.