Chest Computed Tomography Findings in COVID-19 and Influenza: A Narrative Review

Abstract

Objective. The COVID-19 pandemic and annual influenza epidemic are responsible for thousands of deaths globally. With a similarity in clinical as well as laboratory findings, there is a need to differentiate these two conditions on chest CT scan. This paper attempts to use existing literature to draw out differences in chest CT findings in COVID-19 and influenza. Methods. A search was conducted using PubMed. 17 original studies on chest CT findings in COVID-19 and influenza were identified for full-text review and data analysis. Findings. COVID-19 and influenza share similar chest CT findings. The differences found show that COVID-19 ground-glass opacities are usually peripherally located with the lower lobes being commonly involved, while influenza has a central, peripheral, or random distribution usually affecting the five lobes. Vascular engorgement, pleural thickening, and subpleural lines were reported in COVID-19 patients. In contrast, pneumomediastinum and pneumothorax were reported only in studies on influenza. Conclusion and Relevance. COVID-19 and influenza have overlapping chest CT features with few differences which can assist in telling apart the two pathologies. Additional studies are needed to further define the differences and degree between COVID-19 and influenza.

A Comparative Systematic Review of COVID-19 and Influenza

“…In a review from Onigbinde et al, GGO were usually peripherally located and that vascular engorgement, pleural thickening, and subpleural lines were more frequent in COVID-19 patients. Pneumomediastinum and pneumothorax were only reported in influenza studies [ 3 ] ( Table 4 ).…”

“…On PubMed, 331 articles were initially found, out of which 46 articles were selected. In the end, 18 articles were selected [3,[5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21] (8 retrospective studies, 6 cohort studies, 3 casecontrol studies, 1 prospective study, 1 cross-sectional study, 1 review and meta-analysis, and 1 review) ( Figure 1 and Table 1) An outcome-free study population is first identified by the exposure/event of interest and followed in time until the outcome of interest happens. They can be prospective (carried out from the present time into the future) or retrospective (carried out at the present time and look to the past to examine medical events or outcome).…”

“…Both SARS-CoV-2 and influenza virus share similarities such as viral shedding, route of transmission, and clinical presentation [ 2 ]. Influenza affects 5–10% of adults annually with most cases occurring during the winter season [ 3 ]. According to the World Health Organization (WHO), influenza’s epidemics are estimated to result in about 3 to 5 million cases of severe illness, and about 290,000 to 650,000 respiratory deaths [ 4 ].…”

Pleural diseases and COVID-19: ubi fumus, ibi ignis

“…Many of the preceding statements for pneumothorax in the setting of SARS-CoV-2 infection hold true for pneumomediastinum. It is a rare entity, frequently related to mechanical ventilation, which may also appear spontaneously in the context of respiratory infections, like influenza [ 34 ]. In the series by Martinelly et al only 1 (9%) of 11 pneumomediastinum cases was labelled as spontaneous [ 5 ].…”

Artificial Intelligence Empowers Radiologists to Differentiate Pneumonia Induced by COVID-19 versus Influenza Viruses

“…In another study, the COVID-19 patients showed greater number of rounded opacities and interlobular septal thickenings on their chest CT scans but less pulmonary nodules, tree-in-bud opacities and pleural effusions than those with Influenza A and B pneumonias ( 20 ). Even though most CT manifestations of viral infections are nonspecific, the preliminary reports are promising about the role of chest CT images in the differentiation of pneumonias induced by COVID-19 versus those by H1N1 influenza virus ( 21 ).…”