Compelling new research, confirmed by imaging and clinical characteristics, confirm that breakthrough COVID-19 infections are less severe in vaccinated individuals.
Research, led by Dr. Jong Eun Lee of Chonnam National University Hospital in Dong-gu, Gwangju, South Korea, was published February 1 in Radiology. The study supports other evidence that vaccines reduce the severity of COVID-19 in the event of breakthrough infection.
The research group studied the data of 761 adults infected with COVID-19 and who had baseline chest x-rays from a database called the Korean Imaging Cohort for COVID-19 (KICC-19) for the period between June and August 2021. They were classified by vaccination status, and breakthrough infections were defined as when the SARS-CoV-2 RNA or antigen appeared 14 days or more after the patient received their recommended COVID-19 doses.
The senior author of the study, Dr. Yeon Joo Jeong, Ph.D., released to the Radiological Society of North America (RSNA), noting, “Although the risk of infection is much lower among vaccinated individuals, and vaccination reduces the severity of illness, clinical and imaging data of COVID-19 breakthrough infections have not been reported in detail.”
The study detected an extraordinary difference in the occurrence of breakthrough infections of COVID-19 infections when differentiated by vaccine status. The difference was not just in low breakthrough infection rates among the vaccinated:
An astonishing 59% of vaccinated patients had negative CT scan results
for COVID-19 pneumonia.
| Variables | Unvaccinated | Partially Vaccinated | Fully Vaccinated |
| Incidence of breakthrough infections | 77% | 17% | 6.2% |
| Negative for COVID-19 pneumonia on CT scan | 22% | 30% | 59% |
Clinical characteristics reflected additional benefits of COVID-19 vaccination — fully vaccinated patients were less likely to need supplemental oxygen and were less likely to be admitted to Intensive Care Units.
An editorial accompanying the study, by Dr. Mark Schiebler and Dr. David Bluemke, Ph.D., both of the University of Wisconsin-Madison School of Medicine and Public Health, notes that this visual evidence, confirmed by CT scan, is strong evidence of COVID-19 vaccine efficacy.
The researchers are hopeful that the visual radiological evidence of less severe disease will help reinforce the effectiveness of vaccines for public health officials who continue their efforts to overcome vaccine hesitancy.