The variation in the clinical severity of viral infections remains a matter of scientific debate. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and Influenza A virus (IAV) are both RNA viruses, exhibiting a range of clinical presentations, ranging from asymptomatic cases to fatalities, influenced by both viral and host factors. A descriptive real-life study was conducted, aiming to compare the clinical manifestations of recent COVID-19 with those of IAV infection in the same group of non-hospitalised, unvaccinated children.

Between September 2021 and February 2023, we evaluated 115 individuals (male 48.7%, mean age 101.8 ± 50.8 months) who had not received vaccination for both SARS-CoV-2 and the quadrivalent influenza vaccine and were documented to be infected with both viruses within a 12-month time interval. The visual analogue scale (VAS-5) was used to assess parents'/patients' evaluation comparing the two infections.

In cases of IAV infection, a significantly higher prevalence of prolonged high fever, upper and lower respiratory symptoms, and secondary infections was observed. The majority (74.8%) of patients and/or parents assessed IAV as a more severe clinical syndrome compared with SARS-CoV-2.

The clinical burden of IAV was found to be greater than that of SARS-CoV-2 infection in the same unvaccinated children. This variation in clinical severity may provide a reference for effective vaccination policies; however, underlying mechanisms that could explain this difference require further evaluation.

Since the 2019 worldwide pandemic, Severe Acute Respiratory Syndrome coronavirus 2 responsible for COVID-19 disease, not only had global economic repercussions but millions of individuals health were also put at risk. Like any other respiratory illness, COVID-19 has a variety of presentations and radiological features. While COVID-19 infections in the pediatric population generally present with better prognosis and lower mortality rates when compared to those of adults, in the vulnerable populations however, severe presentations are often more frequent and can have catastrophic consequences. This paper will specifically address pediatric presentations of COVID-19 including those suffering from multisystem inflammation, along with their radiologic manifestations and image findings.

It is already well known that infants and children infected with COVID-19 develop mild to moderate forms of the disease, with fever and oropharyngeal congestion being the most common symptoms. However, there are instances when patients claim to be experiencing respiratory symptoms. Because of the repeated lung examinations required in these situations, non-irradiating imaging techniques are preferred. This study's objective is to ascertain the value of lung ultrasonography (LUS) in the medical management of these specific cases.

Infants and children under two years old with SARS-CoV-2 infection were evaluated using LUS. Patients with other respiratory pathologies were excluded by using specific tests. The LUS score (LUSS) was correlated with biomarkers and clinical findings using the Mann-Whitney U test and Spearman's rank correlation rho.

The LUSS for each patient varied from 1 to 8 points out of a maximum of 36 points. The arithmetic mean was 4.47 ± 2.36 (S.D), while the 95% CI for the arithmetic mean was 3.33 to 5.61. Sparse B-lines were present in all enrolled infants and children (100%), while only 36.84% developed alveolar syndrome (confluent B-lines). The lung changes were correlated with their biomarkers, specifically inflammatory markers. The correlation between LUSS and LDH, D-dimers, and IL-6 was a strongly positive one with rho = 0.55 (p = 0.001, 95% CI 0.13 to 0.80) between the LUSS and D-dimer levels and rho = 0.60 (p = 0.03, 95% CI 0.04 to 0.87) between LUSS and D-dimer levels at symptomatic infants and children (with respiratory involvement).

Infants and children under the age of two are prone to develop mild forms of COVID-19 disease with a B-line pattern on LUS, although inflammatory markers have elevated blood levels. Despite the small sample, D-dimer levels and O2 saturation were correlated with LUSS in patients with respiratory involvement, while similar results were also found in the entire lot.