{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,4]],"date-time":"2026-09-04T20:27:29Z","timestamp":1788553649672,"version":"build-2803163510"},"reference-count":40,"publisher":"Cambridge University Press (CUP)","license":[{"start":{"date-parts":[[2026,7,29]],"date-time":"2026-07-29T00:00:00Z","timestamp":1785283200000},"content-version":"unspecified","delay-in-days":209,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0"}],"content-domain":{"domain":["cambridge.org"],"crossmark-restriction":true},"short-container-title":["Epidemiol. Infect."],"published-print":{"date-parts":[[2026]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:p>Evidence describing paediatric COVID-19 and influenza co-infection is limited because influenza circulation was minimal during the early COVID-19 pandemic. We used the National Clinical Cohort Collaborative, a multicentre electronic health record repository, to describe the characteristics and clinical outcomes of paediatric COVID-19 and influenza co-infections in the United States from March 2020\u2013April 2024. We defined co-infection as COVID-19 and influenza identified &lt;7\u00a0days apart. We reported demographics, pre-existing diagnoses, and clinical outcomes and used generalized estimating equation models. We defined clinical outcomes as Severe\/Moderate disease (hospitalization, critical care, or death) versus emergency department\/outpatient encounters. We repeated analyses using varying co-infection definitions to assess robustness of findings. Among 1.53 million patients, 10,277 were co-infected, and 647 (6%) were hospitalized. Co-infections occurred predominantly among children aged &lt;12\u00a0years. The most common pre-existing diagnoses were obesity (24%), asthma (10%), and congenital\/genetic conditions (5%). The risk for Severe\/Moderate disease was greatest among persons aged 0\u20134\u00a0years (adjusted risk ratio (aRR) 3.05; 95% confidence interval (CI): 2.35\u20133.97) and those with \u22652 pre-existing diagnoses (aRR 2.89; 95% CI: 2.43\u20133.43). Similar distributions of disease severity were observed across varying co-infection definitions. This study provides a large-scale epidemiological characterization of paediatric COVID-19 and influenza co-infection and successfully implemented a practical EHR-based co-infection case definition for future analyses.<\/jats:p>","DOI":"10.1017\/s0950268826101915","type":"journal-article","created":{"date-parts":[[2026,7,29]],"date-time":"2026-07-29T09:26:45Z","timestamp":1785317205000},"update-policy":"https:\/\/doi.org\/10.1017\/policypage","source":"Crossref","is-referenced-by-count":1,"title":["Epidemiological characteristics of paediatric COVID-19 and influenza co-infections in the United States, 2020\u20132024"],"prefix":"10.1017","volume":"154","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-8235-167X","authenticated-orcid":false,"given":"Ozair H.","family":"Naqvi","sequence":"first","affiliation":[{"name":"University of Oklahoma Health Sciences"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Aaron M.","family":"Wendelboe","sequence":"additional","affiliation":[{"name":"University of Arkansas for Medical Sciences"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"William H.","family":"Beasley","sequence":"additional","affiliation":[{"name":"University of Oklahoma Health Sciences"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Donna L.","family":"Tyungu","sequence":"additional","affiliation":[{"name":"University of Oklahoma Health Sciences"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Kai","family":"Ding","sequence":"additional","affiliation":[{"name":"University of Oklahoma Health Sciences"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Katrin G.","family":"Kuhn","sequence":"additional","affiliation":[{"name":"University of Oklahoma Health Sciences"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"James J.","family":"Cheng","sequence":"additional","affiliation":[{"name":"University of Oklahoma Health Sciences"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"A. Jared","family":"Anzalone","sequence":"additional","affiliation":[{"name":"University of Nebraska Medical Center"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Amanda E.","family":"Janitz","sequence":"additional","affiliation":[{"name":"University of Oklahoma Health Sciences"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"56","published-online":{"date-parts":[[2026,7,29]]},"reference":[{"key":"S0950268826101915_r3","doi-asserted-by":"publisher","DOI":"10.15585\/mmwr.mm7241a2"},{"key":"S0950268826101915_r17","doi-asserted-by":"publisher","DOI":"10.1093\/ije\/dyab081"},{"key":"S0950268826101915_r38","doi-asserted-by":"publisher","DOI":"10.2196\/38196"},{"key":"S0950268826101915_r28","unstructured":"[28] Centers for Disease Control and Prevention (CDC). (2024) COVID-NET: National Center for Immunization and Respiratory Diseases; Coronavirus and Other Respiratory Viruses Division. https:\/\/www.cdc.gov\/covid\/php\/covid-net\/index.html#:~:text=A%20case%20is%20defined%20as,days%20before%20or%20during%20hospitalization. accessed December 20, 2025"},{"key":"S0950268826101915_r27","unstructured":"[27] Centers for Disease Control and Prevention (CDC). (2024) COVID Data Tracker. U.S. Department of Health and Human Services (CDC). https:\/\/covid.cdc.gov\/covid-data-tracker. accessed December 20, 2025"},{"key":"S0950268826101915_r1","doi-asserted-by":"publisher","DOI":"10.1016\/j.ajem.2016.12.001"},{"key":"S0950268826101915_r22","doi-asserted-by":"publisher","DOI":"10.1542\/peds.2022-060640"},{"key":"S0950268826101915_r24","doi-asserted-by":"publisher","DOI":"10.5281\/zenodo.11194108"},{"key":"S0950268826101915_r19","doi-asserted-by":"publisher","DOI":"10.1093\/cid\/ciac296"},{"key":"S0950268826101915_r15","doi-asserted-by":"publisher","DOI":"10.1093\/jamia\/ocad057"},{"key":"S0950268826101915_r32","doi-asserted-by":"publisher","DOI":"10.1136\/bmjhci-2019-100054"},{"key":"S0950268826101915_r14","doi-asserted-by":"publisher","DOI":"10.5281\/zenodo.15185586"},{"key":"S0950268826101915_r12","doi-asserted-by":"publisher","DOI":"10.1371\/journal.pmed.1001885"},{"key":"S0950268826101915_r30","doi-asserted-by":"publisher","DOI":"10.1001\/jamanetworkopen.2021.43151"},{"key":"S0950268826101915_r40","doi-asserted-by":"publisher","DOI":"10.1016\/S2352-4642(24)00236-0"},{"key":"S0950268826101915_r9","doi-asserted-by":"crossref","first-page":"467","DOI":"10.1097\/INF.0000000000004258","article-title":"Risk factors for poor outcomes in children hospitalized with virus-associated acute lower respiratory infections: A systematic review and meta-analysis","volume":"43","author":"Zin","year":"2024","journal-title":"Pediatric Infectious Disease Journal"},{"key":"S0950268826101915_r4","doi-asserted-by":"publisher","DOI":"10.1542\/peds.2017-2918"},{"key":"S0950268826101915_r16","doi-asserted-by":"publisher","DOI":"10.1542\/peds.2022-059037"},{"key":"S0950268826101915_r5","volume-title":"Pneumonia and Influenza Mortality Surveillance Hyattsville","year":"2024"},{"key":"S0950268826101915_r6","doi-asserted-by":"publisher","DOI":"10.15585\/mmwr.mm7150a4"},{"key":"S0950268826101915_r7","doi-asserted-by":"publisher","DOI":"10.1016\/j.jcvp.2021.100036"},{"key":"S0950268826101915_r23","doi-asserted-by":"publisher","DOI":"10.5281\/zenodo.11194167"},{"key":"S0950268826101915_r25","volume-title":"The Researcher\u2019s Guide to N3C: A National Resource for Analyzing Real-World Health Data","author":"O\u2019Neil","year":"2023"},{"key":"S0950268826101915_r13","unstructured":"[13] Pfaff, E. (2022) COVID-19 Phenotype Documentation, Version 4.0: N3C Phenotype & Data Acquisition Workstream. https:\/\/github.com\/National-COVID-Cohort-Collaborative\/Phenotype_Data_Acquisition\/wiki\/Latest-Phenotype. accessed December 20, 2025"},{"key":"S0950268826101915_r26","unstructured":"[26] Centers for Disease Control and Prevention (CDC) (2023) Influenza Activity in the United States during the 2022\u20132023 Season and Composition of the 2023\u20132024 Influenza Vaccine: National Center for Immunization and Respiratory Diseases (NCIRD). https:\/\/www.cdc.gov\/flu\/whats-new\/22-23-summary-technical-report.html. accessed December 20, 2025"},{"key":"S0950268826101915_r21","doi-asserted-by":"publisher","DOI":"10.5281\/zenodo.11194018"},{"key":"S0950268826101915_r31","first-page":"1","article-title":"The R package geepack for generalized estimating equations","volume":"15","author":"H\u00f8jsgaard","year":"2005","journal-title":"Journal of Statistical Software"},{"key":"S0950268826101915_r39","doi-asserted-by":"publisher","DOI":"10.1016\/S1473-3099(22)00544-8"},{"key":"S0950268826101915_r18","doi-asserted-by":"publisher","DOI":"10.1007\/978-0-387-87959-8_4"},{"key":"S0950268826101915_r33","doi-asserted-by":"publisher","DOI":"10.1016\/S0140-6736(10)61380-3"},{"key":"S0950268826101915_r36","doi-asserted-by":"publisher","DOI":"10.1038\/s41366-022-01094-3"},{"key":"S0950268826101915_r10","doi-asserted-by":"publisher","DOI":"10.3390\/pathogens11040445"},{"key":"S0950268826101915_r35","doi-asserted-by":"publisher","DOI":"10.1038\/ijo.2011.208"},{"key":"S0950268826101915_r8","doi-asserted-by":"publisher","DOI":"10.1016\/j.ijid.2023.08.021"},{"key":"S0950268826101915_r2","doi-asserted-by":"publisher","DOI":"10.15585\/mmwr.mm7029a1"},{"key":"S0950268826101915_r37","doi-asserted-by":"publisher","DOI":"10.15585\/mmwr.mm7338a1"},{"key":"S0950268826101915_r34","doi-asserted-by":"publisher","DOI":"10.1542\/peds.2017-4105"},{"key":"S0950268826101915_r20","doi-asserted-by":"publisher","DOI":"10.1186\/1471-2431-14-199"},{"key":"S0950268826101915_r11","doi-asserted-by":"publisher","DOI":"10.1093\/jamia\/ocaa196"},{"key":"S0950268826101915_r29","unstructured":"[29] Centers for Disease Control and Prevention (CDC). (2024) Influenza Hospitalization Surveillance Network (FluSurv-NET): National Center for Immunization and Respiratory Diseases (NCIRD). https:\/\/www.cdc.gov\/flu\/weekly\/influenza-hospitalization-surveillance.htm.] accessed December 20, 2025"}],"updated-by":[{"DOI":"10.1017\/s0950268826101988","type":"correction","label":"Correction","source":"publisher","updated":{"date-parts":[[2026,7,29]],"date-time":"2026-07-29T00:00:00Z","timestamp":1785283200000}}],"container-title":["Epidemiology and Infection"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.cambridge.org\/core\/services\/aop-cambridge-core\/content\/view\/S0950268826101915","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,7,29]],"date-time":"2026-07-29T09:26:58Z","timestamp":1785317218000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.cambridge.org\/core\/product\/identifier\/S0950268826101915\/type\/journal_article"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026]]},"references-count":40,"alternative-id":["S0950268826101915"],"URL":"https:\/\/doi.org\/10.1017\/s0950268826101915","relation":{},"ISSN":["0950-2688","1469-4409"],"issn-type":[{"value":"0950-2688","type":"print"},{"value":"1469-4409","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026]]},"assertion":[{"value":"\u00a9 The Author(s), 2026. Published by Cambridge University Press","name":"copyright","label":"Copyright","group":{"name":"copyright_and_licensing","label":"Copyright and Licensing"}},{"value":"This is an Open Access article, distributed under the terms of the Creative Commons Attribution licence (http:\/\/creativecommons.org\/licenses\/by\/4.0), which permits unrestricted re-use, distribution and reproduction, provided the original article is properly cited.","name":"license","label":"License","group":{"name":"copyright_and_licensing","label":"Copyright and Licensing"}},{"value":"This content has been made available to all.","name":"free","label":"Free to read"}],"article-number":"e105"}}