Chest HRCT Assessment of COVID-19 Patients in Vaccinated Versus Non-Vaccinated Patients in a Tertiary Care Hospital in Nepal

Abstract

Background: The World Health Organization (WHO) has recommended the use of chest HRCT as a component of the diagnostic process for COVID-19 disease whenever Reverse Transcription-Polymerase Chain Reaction (RT-PCR) testing is unavailable; in cases of delayed test results; or in suspected cases with initial negative RT-PCR test results. The study's aims were to assess the severity of lung involvement in COVID-19 infection using HRCT scans and to compare the chest CT severity scores in vaccinated and unvaccinated COVID-19 patients in perspective of the usefulness of HRCT scores in doing so. Subjects and Methods: This study included imaging and hospital data from COVID 19 patients who were treated at a tertiary hospital's and underwent HRCT in Department of Radiodiagnosis between the months of April and December 2021. The study subjects were the COVID 19 patients with HRCT reports and known COVID vaccination status. The HRCT results of the study population were evaluated and recorded separately by radiologist with a  experience in chest radiology. The involvement of the right upper, middle, and lower lobes as well as the left upper and lower lobes was scored separately to get the CT severity score. All patients clinical and demographic profiles were retrieved from the hospital database. The student t test, Chi square test, and Fisher exact test were used to test for associations. P values under 0.05 were regarded as significant. Results: In our study, 77.6% of patients non-vaccinated and 22.4% were vaccinated for COVID-19. Out of 195 vaccinated patients, 134 patients had received single dose (15.3%) and 62 have received two doses (7.1%) of COVID-19 vaccine. In our study, the CT severity score, among vaccinated patients was severe, moderate and mild in 12.8%, 23.5% and 20.0% respectively. Also, the CT severity score, among non-vaccinated patients was severe, moderate and mild in 27.9%, 18.9% and 14.8% respectively. The most common finding seen in our study was ground glass opacities among vaccinated patients (30.7%), whereas both (GGO and consolidation) was most common findings in non-vaccinated patients (34.8%). Conclusion: In this retrospective study, patients who received the SARS-CoV-2 vaccine (either single or both doses) had lower CT severity scores than non-vaccinated patients. The most accurate method for determining the severity of COVID-19 pneumonia is HRCT.