Comparison of CT lung findings in RT-PCR positive COVID vaccinated and unvaccinated patients in a tertiary COVID-19 hospital

Corona Virus Disease 2019 (COVID-19) caused by Severe Acute Respiratory Syndrome Corona Virus 2 (SARS-CoV-2) was initially reported in Wuhan, China. The disease had a rapid outbreak from then and spread to many parts of the world. WHO characterized COVID-19 as a pandemic on March 11, 2020. Computerized Tomography (CT) chest served as the main modality of assessing disease severity through lung involvement patterns and several scoring methods. The COVID-19 vaccine drive in India was launched on January 16, 2021. Our research aimed to study the lung involvement by CT in COVID positive patients and to compare the lung involvement in vaccinated and unvaccinated cases and also to compare the lung involvement in partial, fully vaccinated and unvaccinated cases. All cases who are Real-Time Reverse Transcription-Polymerase Chain Reaction (RT-PCR) positive for COVID and underwent CT chest imaging in the Department of Radiology, Government ESI Medical College Hospital were included in the study. It was a retrospective case-control study. The total study population was 1501 patients which included 115 completely vaccinated cases, 189 partially vaccinated cases and 1197 unvaccinated cases. 25-point CT severity score was used to assess the extent of lung involvement in CT. In the CT scan, the double dose vaccinated patients had comparatively lower lung involvement than the unvaccinated and single dose vaccinated individuals (p value <0.001). The odds ratio in single dose vaccinated group was 0.73 (p >0.05) showing that single dose vaccination had no significant protection for lung involvement whereas for completely vaccinated group the odds was 0.087. Probability of protection against lung involvement in CT was 91.3% in completely vaccinated group compared to unvaccinated group (p value <0.001). Hence, widespread vaccination drives can help to mitigate the global pandemic and also prevent the future outbreaks.