Introduction
The influenza virus remains a serious threat to the global health system
given the occurrence of three to five million severe cases per year and
the high number of mortalities, particularly during pandemics1,2. This virus gives rise to a disease with
manifestations that are common to some other infections, such as fever,
malaise, and headache 3,4. Three types of influenza
viruses affect humans: A, B, and C 5. Based on the
alterations in the hemagglutinin and neuraminidase surface proteins, the
type A influenza virus is divided into numerous subtypes. The H3N2 and
H1N1 subtypes of influenza A have received considerable attention in
recent years. A critical issue that gives rise to major challenges is
the mutations that occur in the various influenza virus strains,
particularly in the A-H3N2 and A-H1N1 subtypes and the B type6-8.
In the clinic, it is usually impossible to differentiate infection
triggered by various types and subtypes of influenza according to the
clinical manifestations 9,10. Fever is the most
commonly reported sign that presents in more than 90% of patients11,12. Respiratory complications, gastrointestinal
involvement, cardiovascular involvement, and constitutional complaints
(e.g., myalgia, malaise, and fatigue) are some of the other signs and
symptoms of influenza virus infection (10). The radiological
characteristics of subjects with various types of influenza, especially
the 2009 H1N1 strain, have been reported in the previous surveys, where
differences between patients of mild and severe disease have been
discussed. The main findings obtained from radiological investigations
on influenza subjects are ground-glass opacities, areas of
consolidation, or a mixed pattern of these two findings (11, 12). In
this cross-sectional study, we retrospectively evaluated the thoracic CT
findings, serological biomarkers, and clinical features in cases with
confirmed A-H1N1, B- H1N1, and A-H3N2 virus infection.