{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,26]],"date-time":"2026-09-26T12:37:47Z","timestamp":1790426267601,"version":"4.1.0"},"reference-count":39,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2021,8,5]],"date-time":"2021-08-05T00:00:00Z","timestamp":1628121600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["frontiersin.org"],"crossmark-restriction":true},"short-container-title":["Front. Pediatr."],"abstract":"<jats:p><jats:bold>Background:<\/jats:bold> The containment measures adopted during COVID-19 pandemic have influenced the epidemiology of other respiratory viruses.<\/jats:p><jats:p><jats:bold>Aim:<\/jats:bold> We analyzed the modification of the incidence and etiology of lower respiratory tract infections (LRTIs) in young children during COVID-19 pandemic.<\/jats:p><jats:p><jats:bold>Methods:<\/jats:bold> Case series of all children under 2 years old hospitalized at a tertiary care Hospital in the Center of Milan, Italy diagnosed with LRTIs in three consecutive winter seasons (from the 1st of November to the last day of February in 2018\/2019, 2019\/2020 and 2020\/2021). We compared the number of hospitalizations and viral detections in the 2020\/2021 with the average of 2018\/2019 and 2019\/2020 (pre-COVID-19) using the Poisson distribution.<\/jats:p><jats:p><jats:bold>Results:<\/jats:bold> we enrolled 178 patients (66 from 2018\/2019, 96 from 2019\/2020, 16 from 2020\/2021) 94 males (53%) and 84 females (47%), with a median (IQR) age of 5 (2\u201313) months. The number of hospitalizations during the 2020\/2021 season was 80% lower than the average of the pre-COVID-19 seasons (16 vs. 81, <jats:italic>p<\/jats:italic>&amp;lt;<jats:italic>0<\/jats:italic>.001). Overall, 171 (96%) patient's nasopharyngeal aspirate (NPA) detected at least one virus (110, 64%, single-detection, 61, 36%, co-detections). In 2020\/2021 we observed the disappearance of Respiratory Syncytial virus (0 vs. 54, <jats:italic>p<\/jats:italic> &amp;lt; 0.001), Influenza virus (0 vs. 6.5, <jats:italic>p<\/jats:italic> = 0.002), Metapneumovirus (0 vs. 8, <jats:italic>p<\/jats:italic> &amp;lt; 0.001), Parainfluenza viruses (0 vs. 3.5, <jats:italic>p<\/jats:italic> = 0.03) and a significant reduction of Adenovirus (2 vs. 7, <jats:italic>p<\/jats:italic> = 0.03), Bocavirus (2 vs. 7.5, <jats:italic>p<\/jats:italic> = 0.02) and Enterovirus (1 vs. 5, <jats:italic>p<\/jats:italic> = 0.04). No significant difference was found for Rhinoviruses (14 cases vs. 17, <jats:italic>p<\/jats:italic> = 0.2), other Coronaviruses (0 vs. 2, <jats:italic>p<\/jats:italic> = 0.1), and Cytomegalovirus (1 vs. 1, <jats:italic>p<\/jats:italic> = 0.7).<\/jats:p><jats:p><jats:bold>Conclusions:<\/jats:bold> We observed a striking reduction in hospitalizations due to LRTIs and a modification of the etiology, with enveloped viruses mainly affected.<\/jats:p>","DOI":"10.3389\/fped.2021.721005","type":"journal-article","created":{"date-parts":[[2021,8,5]],"date-time":"2021-08-05T05:45:58Z","timestamp":1628142358000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":56,"title":["Disappearance of Seasonal Respiratory Viruses in Children Under Two Years Old During COVID-19 Pandemic: A Monocentric Retrospective Study in Milan, Italy"],"prefix":"10.3389","volume":"9","author":[{"given":"Giulio","family":"Ippolito","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Adriano","family":"La Vecchia","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Giulia","family":"Umbrello","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Giada","family":"Di Pietro","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Patrizia","family":"Bono","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Stefano","family":"Scalia 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