{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,1,7]],"date-time":"2026-01-07T23:33:11Z","timestamp":1767828791657,"version":"3.49.0"},"reference-count":38,"publisher":"MDPI AG","issue":"1","license":[{"start":{"date-parts":[[2022,12,30]],"date-time":"2022-12-30T00:00:00Z","timestamp":1672358400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Innovative Medicines Initiative 2 Joint Undertaking","award":["777363"],"award-info":[{"award-number":["777363"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Vaccines"],"abstract":"<jats:p>Following an extremely low incidence of influenza during the first waves of the ongoing COVID-19 pandemic, the 2021\/22 Northern Hemisphere winter season saw a resurgence of influenza virus circulation. The aim of this study was to describe epidemiology of severe acute respiratory infections (SARIs) among Italian adults and estimate the 2021\/22 season influenza vaccine effectiveness. For this purpose, a test-negative case-control study was conducted in a geographically representative sample of Italian hospitals. Of 753 SARI patients analyzed, 2.5% (N = 19) tested positive for influenza, most of which belonged to the A(H3N2) subtype. Phylogenetic analysis showed that these belonged to the subclade 3C.2a1b.2a.2, which was antigenically different from the 2021\/22 A(H3N2) vaccine component. Most (89.5%) cases were registered among non-vaccinated individuals, suggesting a protective effect of influenza vaccination. Due to a limited number of cases, vaccine effectiveness estimated through the Firth\u2019s penalized logistic regression was highly imprecise, being 83.4% (95% CI: 25.8\u201397.4%) and 83.1% (95% CI: 22.2\u201397.3%) against any influenza type A and A(H3N2), respectively. Exclusion of SARS-CoV-2-positive controls from the model did not significantly change the base-case estimates. Within the study limitations, influenza vaccination appeared to be effective against laboratory-confirmed SARI.<\/jats:p>","DOI":"10.3390\/vaccines11010083","type":"journal-article","created":{"date-parts":[[2022,12,30]],"date-time":"2022-12-30T03:31:17Z","timestamp":1672371077000},"page":"83","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":8,"title":["Surveillance of Severe Acute Respiratory Infection and Influenza Vaccine Effectiveness among Hospitalized Italian Adults, 2021\/22 Season"],"prefix":"10.3390","volume":"11","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-2677-0551","authenticated-orcid":false,"given":"Donatella","family":"Panatto","sequence":"first","affiliation":[{"name":"Department of Health Sciences (DISSAL), University of Genoa, 16132 Genoa, Italy"},{"name":"Interuniversity Research Center on Influenza and Other Transmissible Infections (CIRI-IT), 16132 Genoa, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9608-8892","authenticated-orcid":false,"given":"Alexander","family":"Domnich","sequence":"additional","affiliation":[{"name":"Hygiene Unit, San Martino Policlinico Hospital-IRCCS for Oncology and Neurosciences, 16132 Genoa, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1043-1256","authenticated-orcid":false,"given":"Maria","family":"Chironna","sequence":"additional","affiliation":[{"name":"Interdisciplinary Department of Medicine, University of Bari, 70124 Bari, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2057-9745","authenticated-orcid":false,"given":"Daniela","family":"Loconsole","sequence":"additional","affiliation":[{"name":"Interdisciplinary Department of Medicine, University of Bari, 70124 Bari, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5775-2276","authenticated-orcid":false,"given":"Christian","family":"Napoli","sequence":"additional","affiliation":[{"name":"Sant\u2019Andrea Hospital, University La Sapienza, 00189 Rome, Italy"},{"name":"Department of Medical Surgical Sciences and Translational Medicine, \u201cSapienza\u201d University of Rome, 00189 Rome, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Alessandra","family":"Torsello","sequence":"additional","affiliation":[{"name":"Sant\u2019Andrea Hospital, University La Sapienza, 00189 Rome, Italy"},{"name":"Department of Medical Surgical Sciences and Translational Medicine, \u201cSapienza\u201d University of Rome, 00189 Rome, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5877-3095","authenticated-orcid":false,"given":"Ilaria","family":"Manini","sequence":"additional","affiliation":[{"name":"Department of Molecular and Developmental Medicine, University of Siena, 53100 Siena, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7595-4974","authenticated-orcid":false,"given":"Emanuele","family":"Montomoli","sequence":"additional","affiliation":[{"name":"Department of Molecular and Developmental Medicine, University of Siena, 53100 Siena, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5681-3455","authenticated-orcid":false,"given":"Elena","family":"Pariani","sequence":"additional","affiliation":[{"name":"Department of Biomedical Sciences for Health, University of Milan, 20133 Milan, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1716-6624","authenticated-orcid":false,"given":"Silvana","family":"Castaldi","sequence":"additional","affiliation":[{"name":"Department of Biomedical Sciences for Health, University of Milan, 20133 Milan, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2433-9610","authenticated-orcid":false,"given":"Andrea","family":"Orsi","sequence":"additional","affiliation":[{"name":"Department of Health Sciences (DISSAL), University of Genoa, 16132 Genoa, Italy"},{"name":"Interuniversity Research Center on Influenza and Other Transmissible Infections (CIRI-IT), 16132 Genoa, Italy"},{"name":"Hygiene Unit, San Martino Policlinico Hospital-IRCCS for Oncology and Neurosciences, 16132 Genoa, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8463-8487","authenticated-orcid":false,"given":"Giancarlo","family":"Icardi","sequence":"additional","affiliation":[{"name":"Department of Health Sciences (DISSAL), University of Genoa, 16132 Genoa, Italy"},{"name":"Interuniversity Research Center on Influenza and Other Transmissible Infections (CIRI-IT), 16132 Genoa, Italy"},{"name":"Hygiene Unit, San Martino Policlinico Hospital-IRCCS for Oncology and Neurosciences, 16132 Genoa, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"name":"on behalf of the IT-BIVE-HOSP Network Study Group","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2022,12,30]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1173","DOI":"10.3201\/eid2407.171270","article-title":"Progress and remaining gaps in estimating the global 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