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. Per CDC, the number of reported COVID-19 vaccine breakthrough cases is likely a substantial undercount of all SARS-CoV-2 infections among fully vaccinated. There were 160 deaths among vaccinated in April vs 535 in May. As of June 1, 2021, more than 135 million people in the United States had been fully vaccinated against COVID-19. During the same time, CDC received reports from 47 U.S. states and territories of 3,016 patients with COVID-19 vaccine breakthrough infection who were hospitalized or died. Total number of vaccine breakthrough infections reported to CDC Hospitalized or fatal vaccine breakthrough cases reported to CDC 3,016 Female 1,492 (49%) People aged ≥65 years 2,334 (77%) Asymptomatic infections 502 (17%) Hospitalizations* 2,854 (95%) Deaths† 535 (18%) *654 (23%) of 2,854 hospitalizations reported as asymptomatic or not related to COVID-19. †88 (16%) of 535 fatal cases reported as asymptomatic or not related to COVID-19. New variants such as delta and new Vietnamese variant will continue to present a challenge for vaccinated and those with post infection natural immunity due to vaccine& natural immunity viral escape and new mutations with potentially largest deadly covid wave expected from this fall September into spring 2022.

https://www.cdc.gov/vaccines/covid-19/health-departments/breakthrough-cases.html