BACKGROUND: Solid organ transplant recipients (SOTR) have diminished humoral immune responses to COVID-19 vaccination and higher rates of COVID-19 vaccine breakthrough infection than the general population. Little is known about COVID-19 disease severity in SOTR with COVID-19 vaccine breakthrough infections. METHODS: Between 4/7/21 and 6/21/21, we requested case reports via the Emerging Infections Network (EIN) listserv of SARS-CoV-2 infection following COVID-19 vaccination in SOTR. Online data collection included patient demographics, dates of COVID-19 vaccine administration, and clinical data related to COVID-19. We performed a descriptive analysis of patient factors and evaluated variables contributing to critical disease or need for hospitalization. RESULTS: Sixty-six cases of SARS-CoV-2 infection after vaccination in SOTR were collected. COVID-19 occurred after the second vaccine dose in 52 (78.8%) cases, of which 43 (82.7%) occurred ≥14 days post-vaccination. There were six deaths, three occurring in fully vaccinated individuals (7.0%, n = 3/43). There was no difference in the percentage of patients who recovered from COVID-19 (70.7% vs. 72.2%, p = .90) among fully and partially vaccinated individuals. We did not identify any differences in hospitalization (60.5% vs. 55.6%, p = .72) or critical disease (20.9% vs. 33.3%, p = .30) among those who were fully versus partially vaccinated. CONCLUSIONS: SOTR vaccinated against COVID-19 can still develop severe, and even critical, COVID-19 disease. Two doses of mRNA COVID-19 vaccine may be insufficient to protect against severe disease and mortality in SOTR. Future studies to define correlates of protection in SOTR are needed.