Here’s a link to a May 25 CDC report on COVID-19 Vaccine Breakthrough Infections:
https://www.cdc.gov/mmwr/volumes/70/wr/mm7021e3.htm
Snippets:
A total of 10,262 SARS-CoV-2 vaccine breakthrough infections had been reported from 46 U.S. states and territories as of April 30, 2021.
Based on preliminary data, 2,725 (27%) vaccine breakthrough infections were asymptomatic, 995 patients were known to be hospitalized, and 160 patients died. Among the 995 hospitalized patients, 289 were asymptomatic or hospitalized for a reason unrelated to COVID-19. The median age of patients who died was 82 years; 28 decedents were asymptomatic or died from a cause unrelated to COVID-19.
The number of reported COVID-19 vaccine breakthrough cases is likely a substantial undercount of all SARS-CoV-2 infections among fully vaccinated persons.
Beginning May 1, 2021, CDC transitioned from monitoring all reported COVID-19 vaccine breakthrough infections to investigating only those among patients who are hospitalized or die, thereby focusing on the cases of highest clinical and public health significance.
CDC will continue to lead studies in multiple U.S. sites to evaluate vaccine effectiveness and collect information on all COVID-19 vaccine breakthrough infections regardless of clinical status.