Clinical Characteristics of Paediatric RSV, Influenza, and SARS-CoV-2 Infections: Insights from Three Consecutive Seasons.

BACKGROUND: The purpose of this study was to retrospectively analyse the clinical presentation of RSV, Influenza, and SARS-CoV-2 infections in children across three consecutive seasons (2022/2023; 2023/2024; and 2024/2025). METHODS: Of the 321 hospitalised patients, 129 (36%) tested positive for RSV, 110 (38%) for Influenza, and 82 (26%) for SARS-CoV-2. Children were aged ≤ 17 years (median: 15 months). The data were statistically analysed using the χ2 test, multinomial multivariable logistic regression, OR (odds ratio), and 95% CI (confidence interval). RESULTS: Significant independent predictors of RSV infection were auscultatory abnormalities (OR: 15.9 [1.49-169]) and hospital admission ≥ 4 days after symptom onset (OR: 32.5 [1.19-907]). Among RSV-positive patients, compared with those aged < 6 months, those aged 7-24 months were more likely to present with higher CRP levels (OR 1.06 [1.003-1.13]), reduced appetite (OR 6.7 [1.62-27.67]), and longer duration of fever (OR 7.22 [1.47-35.59]), while in children > 24 months, only a longer duration of fever remained significant (OR 16.82 [2.14-162.4]). In Influenza, reduced appetite was the only characteristic feature in the 7-24-month age group (OR 13.55 [1.79-102.81]). In COVID-19, children aged 7-24 months more frequently had higher CRP levels (OR 1.108 [1.001-1.226]) and chronic diseases (OR 7.59 [1.115-51.64]), whereas in those >24 months, only CRP was significant (OR 1.16 [1.047-1.31]). CONCLUSIONS: RSV was associated with severe respiratory manifestations and later hospital admission, whereas Influenza and SARS-CoV-2 were characterised by milder courses with predominant upper respiratory symptoms. Observed age- and virus-specific patterns highlight the importance of continued surveillance and comparative research on major respiratory viruses in children.