A new study published in the journal Radiology has found that COVID-19 breakthrough infections in fully vaccinated people tend to be milder compared to those who are partially vaccinated or unvaccinated, according to Science Daily.
Worldwide, the number of confirmed COVID-19 cases exceeded 382 million, with 5.7 million deaths.
COVID vaccines have been found effective at preventing the infection and bringing the pandemic under control. However, they are not 100% effective at preventing COVID illness.
Breakthrough infections are on the rise due to the highly transmissible Omicron variant. Therefore, it is important to know how vaccines affect COVID-19 disease severity, clinical data, as well as medical imaging results.
Senior author Dr. Yeon Joo Jeong of Pusan National University Hospital in Busan, South Korea, said, “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 purpose of this study was to document the clinical and imaging features of COVID-19 breakthrough infections and compare them with those of infections in unvaccinated patients.”
In this retrospective multicenter cohort study, Dr. Jeong and her colleagues analyzed more than 760 hospitalized patients, of which, 47 were fully vaccinated, 127 were partially vaccinated, and 587 were unvaccinated.
Chest CT was performed on 412 (54%) patients during hospitalization. Of those who underwent CT, the proportion of CT scans without pneumonia was 22% (71/326) of unvaccinated patients, 30% (19/64) of partially vaccinated patients, and 59% (13/22) of fully vaccinated patients, per Science Daily.
The researchers found that individuals with fully vaccinated status were associated with a lower risk of requiring supplemental oxygen than those who were unvaccinated. Also, fully vaccinated patients had a lower risk of intensive care unit (ICU) admission.
The findings also showed associations between the risk of severe illness and clinical characteristics, such as age, diabetes, lymphocytopenia, thrombocytopenia, increased LDH (lactate dehydrogenase), and elevated CRP (C-reactive protein) levels.
The researchers noted that age was an important predictor of more severe illness in COVID-19 patients, even in people with breakthrough infections.
Dr. Jeong explained, “Despite these differences, mechanical ventilation and in-hospital death occurred only in the unvaccinated group.”
“Furthermore, after adjusting for baseline clinical characteristics, analysis showed that fully vaccinated patients were at significantly lower risk of requiring supplemental oxygen and of ICU admission than unvaccinated patients,” she added.
The authors said that additional studies would be needed as different variants emerge. However, this study highlights the clinical efficacy of COVID-19 vaccines in the context of breakthrough infections.
