{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,28]],"date-time":"2026-10-28T05:23:43Z","timestamp":1793165023100,"version":"4.5.0"},"reference-count":44,"publisher":"MDPI AG","issue":"12","license":[{"start":{"date-parts":[[2025,11,30]],"date-time":"2025-11-30T00:00:00Z","timestamp":1764460800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Viruses"],"abstract":"<jats:p>Seasonal influenza is a major cause of morbidity and hospitalization in children, with the potential for severe complications and considerable socioeconomic impact. We conducted a retrospective observational study including 1046 children aged 0\u201314 years with laboratory-confirmed influenza who accessed the Paediatric Emergency Department of a tertiary center in Bologna, Italy, across three consecutive epidemic seasons (2022\u20132025). While the entire cohort was analysed, particular attention was given to children with severe complications requiring hospitalization, for whom more detailed clinical and laboratory data were available. Overall, 12.3% of patients required hospitalization, and 6.1% experienced complications, most frequently influenza-associated encephalopathy, lower respiratory tract infections and myositis. Influenza A predominated overall (82.0%), except for in the last season, which saw a predominance of influenza B (57.4%), closely associated with myositis and elevated creatine phosphokinase levels. Younger age was consistently associated with increased severity and hospitalization. Intensive care admissions were rare (0.8%), and no deaths were recorded. Our findings suggest that, although influenza is generally self-limiting, younger children are at higher risk of complications. These results highlight the importance of active surveillance, careful monitoring of clinical manifestations and targeted paediatric vaccination strategies to reduce the burden of seasonal influenza.<\/jats:p>","DOI":"10.3390\/v17121574","type":"journal-article","created":{"date-parts":[[2025,12,1]],"date-time":"2025-12-01T13:03:02Z","timestamp":1764594182000},"page":"1574","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":7,"title":["Burden and Clinical Characteristics of Influenza and Its Complications in Children Across Multiple Epidemic Seasons"],"prefix":"10.3390","volume":"17","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-7516-243X","authenticated-orcid":false,"given":"Arianna","family":"Dondi","sequence":"first","affiliation":[{"name":"Pediatric Unit, IRCCS Azienda Ospedaliero-Universitaria of Bologna, 40138 Bologna, Italy"},{"name":"Department of Medical and Surgical Sciences, Alma Mater Studiorum, University of Bologna, 40137 Bologna, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1727-5372","authenticated-orcid":false,"given":"Fiorentina","family":"Guida","sequence":"additional","affiliation":[{"name":"Pediatric Unit, IRCCS Azienda Ospedaliero-Universitaria of Bologna, 40138 Bologna, Italy"},{"name":"Department of Medical and Surgical Sciences, Alma Mater Studiorum, University of Bologna, 40137 Bologna, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ludovica","family":"Trombetta","sequence":"additional","affiliation":[{"name":"Speciality School of Paediatrics, Alma Mater Studiorum, University of Bologna, 40137 Bologna, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Maddalena","family":"De Peppo Cocco","sequence":"additional","affiliation":[{"name":"Speciality School of Paediatrics, Alma Mater Studiorum, University of Bologna, 40137 Bologna, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2596-2367","authenticated-orcid":false,"given":"Giulia","family":"Piccirilli","sequence":"additional","affiliation":[{"name":"Microbiology Unit, IRCCS Azienda Ospedaliero-Universitaria di Bologna, 40138 Bologna, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7755-9652","authenticated-orcid":false,"given":"Laura","family":"Andreozzi","sequence":"additional","affiliation":[{"name":"Pediatric Unit, IRCCS Azienda Ospedaliero-Universitaria of Bologna, 40138 Bologna, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Eleonora","family":"Battelli","sequence":"additional","affiliation":[{"name":"Pediatric Unit, IRCCS Azienda Ospedaliero-Universitaria of Bologna, 40138 Bologna, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0006-8860-5590","authenticated-orcid":false,"given":"Pasquale","family":"Castaldo","sequence":"additional","affiliation":[{"name":"Speciality School of Paediatrics, Alma Mater Studiorum, University of Bologna, 40137 Bologna, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ilaria","family":"Corsini","sequence":"additional","affiliation":[{"name":"Pediatric Unit, IRCCS Azienda Ospedaliero-Universitaria of Bologna, 40138 Bologna, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8175-5488","authenticated-orcid":false,"given":"Luca","family":"Pierantoni","sequence":"additional","affiliation":[{"name":"Pediatric Unit, IRCCS Azienda Ospedaliero-Universitaria of Bologna, 40138 Bologna, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Martina","family":"Franceschiello","sequence":"additional","affiliation":[{"name":"Microbiology Unit, IRCCS Azienda Ospedaliero-Universitaria di Bologna, 40138 Bologna, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5994-4749","authenticated-orcid":false,"given":"Liliana","family":"Gabrielli","sequence":"additional","affiliation":[{"name":"Microbiology Unit, IRCCS Azienda Ospedaliero-Universitaria di Bologna, 40138 Bologna, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Monia","family":"Gennari","sequence":"additional","affiliation":[{"name":"Pediatric Unit, IRCCS Azienda Ospedaliero-Universitaria of Bologna, 40138 Bologna, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Dalila","family":"Periccioli","sequence":"additional","affiliation":[{"name":"Speciality School of Paediatrics, Alma Mater Studiorum, University of Bologna, 40137 Bologna, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3093-363X","authenticated-orcid":false,"given":"Tiziana","family":"Lazzarotto","sequence":"additional","affiliation":[{"name":"Department of Medical and Surgical Sciences, Alma Mater Studiorum, University of Bologna, 40137 Bologna, Italy"},{"name":"Microbiology Unit, IRCCS Azienda Ospedaliero-Universitaria di Bologna, 40138 Bologna, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9895-5942","authenticated-orcid":false,"given":"Daniele","family":"Zama","sequence":"additional","affiliation":[{"name":"Pediatric Unit, IRCCS Azienda Ospedaliero-Universitaria of Bologna, 40138 Bologna, Italy"},{"name":"Department of Medical and Surgical Sciences, Alma Mater Studiorum, University of Bologna, 40137 Bologna, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Marcello","family":"Lanari","sequence":"additional","affiliation":[{"name":"Pediatric Unit, IRCCS Azienda Ospedaliero-Universitaria of Bologna, 40138 Bologna, Italy"},{"name":"Department of Medical and Surgical Sciences, Alma Mater Studiorum, University of Bologna, 40137 Bologna, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2025,11,30]]},"reference":[{"key":"ref_1","unstructured":"World Health Organization (2025, September 23). Influenza (Seasonal). WHO Fact Sheet, Available online: https:\/\/www.who.int\/news-room\/fact-sheets\/detail\/influenza-(seasonal)."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"528","DOI":"10.1038\/s41579-021-00535-6","article-title":"Transmissibility and Transmission of Respiratory Viruses","volume":"19","author":"Leung","year":"2021","journal-title":"Nat. Rev. Microbiol."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"605","DOI":"10.1542\/pir.2023-005962","article-title":"Influenza in Children and Adolescents: Epidemiology, Management, and Prevention","volume":"44","author":"Wolf","year":"2023","journal-title":"Pediatr. Rev."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"3","DOI":"10.1038\/s41572-018-0002-y","article-title":"Influenza","volume":"4","author":"Krammer","year":"2018","journal-title":"Nat. Rev. Dis. Primers"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"693","DOI":"10.1016\/S0140-6736(22)00982-5","article-title":"Influenza","volume":"400","author":"Uyeki","year":"2022","journal-title":"Lancet"},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"697","DOI":"10.1016\/S0140-6736(17)30129-0","article-title":"Influenza","volume":"390","author":"Paules","year":"2017","journal-title":"Lancet"},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"489","DOI":"10.1097\/INF.0000000000002610","article-title":"Comparative Severity of Influenza A and B Infections in Hospitalized Children","volume":"39","author":"Mattila","year":"2020","journal-title":"Pediatr. Infect. Dis. J."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"1188","DOI":"10.1017\/S1047951121004777","article-title":"Influenza Myocarditis in Paediatric Patients","volume":"32","author":"Dolader","year":"2022","journal-title":"Cardiol. Young"},{"key":"ref_9","doi-asserted-by":"crossref","unstructured":"Agyeman, P., and Duppenthaler, A. (2004). Influenza-Associated Myositis in Children. Infection, 32.","DOI":"10.1007\/s15010-004-4003-2"},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"32","DOI":"10.1016\/j.jpeds.2021.06.075","article-title":"Prevalence, Risk Factors, and Outcomes of Influenza-Associated Neurologic Complications in Children","volume":"239","author":"Antoon","year":"2021","journal-title":"J. Pediatr."},{"key":"ref_11","doi-asserted-by":"crossref","unstructured":"Lafond, K.E., and Nair, H. (2016). Global Role and Burden of Influenza in Pediatric Respiratory Hospitalizations, 1982\u20132012: A Systematic Analysis. PLoS Med., 13.","DOI":"10.1371\/journal.pmed.1002060"},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"e440","DOI":"10.1097\/INF.0000000000004090","article-title":"Epidemiology and Burden of Influenza in Children 0\u201314 Years over Ten Consecutive Seasons in Italy","volume":"42","author":"Barbieri","year":"2023","journal-title":"Pediatr. Infect. Dis. J."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"351","DOI":"10.1111\/irv.12925","article-title":"The Burden of Seasonal Influenza in Italy: A Systematic Review of Influenza-related Complications, Hospitalizations, and Mortality","volume":"16","author":"Giacchetta","year":"2022","journal-title":"Influenza Resp. Viruses"},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"1492","DOI":"10.1093\/cid\/cix1040","article-title":"Efficacy and Safety of Oseltamivir in Children: Systematic Review and Individual Patient Data Meta-Analysis of Randomized Controlled Trials","volume":"66","author":"Malosh","year":"2018","journal-title":"Clin. Infect. Dis."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"e2021050417","DOI":"10.1542\/peds.2021-050417","article-title":"Influenza Antiviral Treatment and Length of Stay","volume":"148","author":"Campbell","year":"2021","journal-title":"Pediatrics"},{"key":"ref_16","doi-asserted-by":"crossref","unstructured":"Committee on Infectious Diseases, O\u2019Leary, S.T., and Campbell, J.D. (2024). Recommendations for Prevention and Control of Influenza in Children, 2024\u20132025: Policy Statement. Pediatrics, 154, e2024068507.","DOI":"10.1542\/peds.2024-068507"},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"417","DOI":"10.1016\/j.jiph.2023.12.018","article-title":"Characterization of an Influenza B Virus Isolated from a Fatal Case of Myocarditis in a Pediatric Patient in Italy","volume":"17","author":"Puzelli","year":"2024","journal-title":"J. Infect. Public Health"},{"key":"ref_18","doi-asserted-by":"crossref","unstructured":"Committee on Infectious Diseases (2022). Recommendations for Prevention and Control of Influenza in Children, 2022\u20132023. Pediatrics, 150, e2022059275.","DOI":"10.1542\/peds.2022-059274"},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"956","DOI":"10.1001\/jamapediatrics.2015.1387","article-title":"Influenza A Virus Infection, Innate Immunity, and Childhood","volume":"169","author":"Coates","year":"2015","journal-title":"JAMA Pediatr."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"145","DOI":"10.1016\/j.jinf.2021.11.006","article-title":"Burden of Influenza Disease in Children under 2 Years of Age Hospitalized between 2011 and 2020 in France","volume":"84","author":"Tillard","year":"2022","journal-title":"J. Infect."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"1013","DOI":"10.15585\/mmwr.mm7029a1","article-title":"Changes in Influenza and Other Respiratory Virus Activity During the COVID-19 Pandemic\u2014United States, 2020\u20132021","volume":"70","author":"Olsen","year":"2021","journal-title":"MMWR Morb. Mortal. Wkly. Rep."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"108173","DOI":"10.1016\/j.ijid.2025.108173","article-title":"Changes of Dynamics of Influenza before and after COVID-19 Pandemic: A Global Study in Eight Regions","volume":"162","author":"Zhang","year":"2026","journal-title":"Int. J. Infect. Dis."},{"key":"ref_23","doi-asserted-by":"crossref","unstructured":"Chen, W., and Wang, H. (2025). Impact of COVID-19 Control Measures on Influenza Positivity among Patients with Acute Respiratory Infections, 2018\u20132023: An Interrupted Time Series Analysis. BMC Infect. Dis., 25.","DOI":"10.1186\/s12879-025-11279-6"},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"1500","DOI":"10.1093\/infdis\/jiab485","article-title":"Quantifying the Impact of COVID-19 Nonpharmaceutical Interventions on Influenza Transmission in the United States","volume":"224","author":"Qi","year":"2021","journal-title":"J. Infect. Dis."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"1511","DOI":"10.1093\/cid\/cix1060","article-title":"Seasonal Incidence of Symptomatic Influenza in the United States","volume":"66","author":"Tokars","year":"2018","journal-title":"Clin. Infect. Dis."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"340","DOI":"10.1126\/science.1154137","article-title":"The Global Circulation of Seasonal Influenza A (H3N2) Viruses","volume":"320","author":"Russell","year":"2008","journal-title":"Science"},{"key":"ref_27","unstructured":"Ribotta, V.G. (2025, November 28). Influenza Prevention and Control: Recommendations for the Season 2025\u20132026, Available online: https:\/\/www.salute.gov.it\/new\/it\/news-e-media\/notizie\/influenza-pubblicata-la-circolare-con-le-raccomandazioni-la-stagione-2025-2026\/."},{"key":"ref_28","unstructured":"Istituto Superiore di Sanit\u00e0 (2022). Influenza Vaccination Coverage in Italy, Season 2021\u20132022, Istituto Superiore di Sanit\u00e0."},{"key":"ref_29","unstructured":"Istituto Superiore di Sanit\u00e0 (2023). Influenza Vaccination Coverage in Italy, Season 2022\u20132023, Istituto Superiore di Sanit\u00e0."},{"key":"ref_30","unstructured":"Istituto Superiore di Sanit\u00e0 (2024). Influenza Vaccination Coverage in Italy, Season 2023\u20132024, Istituto Superiore di Sanit\u00e0."},{"key":"ref_31","unstructured":"Istituto Superiore di Sanit\u00e0 (2025). Influenza Vaccination Coverage in Italy, Season 2024\u20132025, Istituto Superiore di Sanit\u00e0."},{"key":"ref_32","doi-asserted-by":"crossref","unstructured":"Oh, Y.N., and Kim, S. (2019). Clinical Similarities between Influenza A and B in Children: A Single-Center Study, 2017\/18 Season, Korea. BMC Pediatr., 19.","DOI":"10.1186\/s12887-019-1862-3"},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"575","DOI":"10.1002\/jmv.27400","article-title":"Severe Influenza Virus Infection in Children Admitted to the PICU: Comparison of Influenza A and Influenza B Virus Infection","volume":"94","author":"Turanli","year":"2022","journal-title":"J. Med. Virol."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"12853","DOI":"10.1038\/s41598-019-49273-z","article-title":"Epidemiological and Clinical Characteristics of Children Hospitalized Due to Influenza A and B in the South of Europe, 2010\u20132016","volume":"9","author":"Vidal","year":"2019","journal-title":"Sci. Rep."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"530","DOI":"10.1007\/s00431-025-06338-8","article-title":"Characteristics of Children with Influenza Admitted to a Pediatric Hospital in Greece during the 2022\/2023 and 2023\/2024 Seasons","volume":"184","author":"Dimopoulou","year":"2025","journal-title":"Eur. J. Pediatr."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"e684","DOI":"10.1542\/peds.2014-0505","article-title":"Severe Complications in Influenza-like Illnesses","volume":"134","author":"Mistry","year":"2014","journal-title":"Pediatrics"},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"1930","DOI":"10.1093\/cid\/ciac296","article-title":"Epidemiology, Clinical Characteristics, and Outcomes of Influenza-Associated Hospitalizations in US Children over 9 Seasons Following the 2009 H1N1 Pandemic","volume":"75","author":"Kamidani","year":"2022","journal-title":"Clin. Infect. Dis."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"686","DOI":"10.1093\/infdis\/jit473","article-title":"Complications and Associated Bacterial Coinfections Among Children Hospitalized With Seasonal or Pandemic Influenza, United States, 2003\u20132010","volume":"209","author":"Dawood","year":"2014","journal-title":"J. Infect. Dis."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"599","DOI":"10.1007\/s00431-025-06450-9","article-title":"Increase in Benign Acute Childhood Myositis in the Post-COVID Era: A Retrospective Study from a Tertiary Pediatric Center","volume":"184","author":"Brisca","year":"2025","journal-title":"Eur. J. Pediatr."},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"4641","DOI":"10.1007\/s00431-024-05786-y","article-title":"Benign Acute Childhood Myositis: A Scoping Review of Clinical Presentation and Viral Etiology","volume":"183","author":"Majava","year":"2024","journal-title":"Eur. J. Pediatr."},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"24","DOI":"10.1016\/j.jpeds.2021.07.039","article-title":"Influenza-Associated Neurologic Complications in Hospitalized Children","volume":"239","author":"Frankl","year":"2021","journal-title":"J. Pediatr."},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"e13075","DOI":"10.1111\/irv.13075","article-title":"Neurological Complications Associated with Influenza in Hospitalized Children","volume":"17","author":"Jantarabenjakul","year":"2023","journal-title":"Influenza Resp. Viruses"},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"895","DOI":"10.1093\/cid\/ciy874","article-title":"Clinical Practice Guidelines by the Infectious Diseases Society of America: 2018 Update on Diagnosis, Treatment, Chemoprophylaxis, and Institutional Outbreak Management of Seasonal Influenzaa","volume":"68","author":"Uyeki","year":"2019","journal-title":"Clin. Infect. Dis."},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"e200009","DOI":"10.1590\/0074-02760200009","article-title":"Influenza A(H1N1)Pdm09 Infection and Viral Load Analysis in Patients with Different Clinical Presentations","volume":"115","author":"Perosa","year":"2020","journal-title":"Mem. Inst. 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