{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,18]],"date-time":"2026-09-18T10:05:41Z","timestamp":1789725941441,"version":"4.0.1"},"reference-count":12,"publisher":"Oxford University Press (OUP)","issue":"9","license":[{"start":{"date-parts":[[2026,8,27]],"date-time":"2026-08-27T00:00:00Z","timestamp":1787788800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by-nc-nd\/4.0\/"}],"funder":[{"DOI":"10.13039\/100014588","name":"Sanofi-Pasteur","doi-asserted-by":"publisher","id":[{"id":"10.13039\/100014588","id-type":"DOI","asserted-by":"publisher"}]},{"name":"THRIVE COIN"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"published-print":{"date-parts":[[2026,9,1]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:sec>\n                    <jats:title>Background<\/jats:title>\n                    <jats:p>Influenza outbreaks in US nursing homes contribute substantially to morbidity, mortality, and operational strain. Recombinant influenza vaccine may reduce transmission in long-term care settings, but high-quality evidence to support this effect is limited. The purpose of this study was to compare the risk of influenza outbreaks (influenza confirmed: 1 or more laboratory-confirmed cases; influenza suspected: 2 or more influenza-like illness cases) among nursing homes randomized to recombinant quadrivalent influenza vaccine (RIV4) vs standard-dose egg-based inactivated quadrivalent influenza vaccine (IIV4).<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>This study was a pragmatic, cluster-randomized clinical trial conducted across 2 influenza seasons (n = 965 facilities in 2019\u20132020 and n = 1023 in 2020\u20132021) in Medicare-certified US nursing homes. Nursing homes with \u226550 long-stay residents and high proportions of adults aged \u226565 years were eligible and assigned to RIV4 or IIV4 for resident and staff vaccination. The outcome was facility-reported influenza outbreaks, assessed by monthly logs.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>During the 2019\u20132020 season, RIV4-assigned facilities experienced fewer suspected (148 [30.6%] vs 178 [37.0%]) and laboratory-confirmed (177 [36.6%] vs 214 [44.5%]) influenza outbreaks than IIV4 facilities. The adjusted relative risk (RR) for confirmed outbreaks was 0.82 (95% CI, 0.71\u20130.96). In 2020\u20132021, confirmed outbreaks were rare (16 vs 15), and no significant differences were observed. Coronavirus disease 2019 outbreak risk did not differ between groups in either season.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusions<\/jats:title>\n                    <jats:p>RIV4 reduced influenza outbreak occurrence in US nursing homes during a season with moderate influenza activity in older adults. No differences were observed during the low-circulation 2020\u20132021 season. These findings suggest that recombinant influenza vaccines may provide clinically meaningful facility-level benefits in long-term care settings during seasons with substantial influenza circulation.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.1093\/ofid\/ofag522","type":"journal-article","created":{"date-parts":[[2026,8,25]],"date-time":"2026-08-25T11:39:09Z","timestamp":1787657949000},"source":"Crossref","is-referenced-by-count":0,"title":["Recombinant Influenza Vaccine and Influenza Outbreaks in US Nursing Homes: Results From a Pragmatic Cluster-Randomized Clinical Trial"],"prefix":"10.1093","volume":"13","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-5056-0431","authenticated-orcid":false,"given":"Kevin W","family":"McConeghy","sequence":"first","affiliation":[{"name":"Transformative Health Systems Research to Improve Veteran Equity and Independence Center of Innovation (THRIVE COIN), Veterans Affairs Providence Health Care System , Providence, Rhode Island ,","place":["USA"]},{"name":"Department of Health Services, Policy & Practice, Brown University School of Public Health , Providence, Rhode Island ,","place":["USA"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7924-0140","authenticated-orcid":false,"given":"H","family":"Edward Davidson","sequence":"additional","affiliation":[{"name":"Insight Therapeutics LLC , Norfolk, Virginia ,","place":["USA"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9451-084X","authenticated-orcid":false,"given":"Lisa","family":"Han","sequence":"additional","affiliation":[{"name":"Insight Therapeutics LLC , Norfolk, Virginia ,","place":["USA"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5503-7888","authenticated-orcid":false,"given":"David H","family":"Canaday","sequence":"additional","affiliation":[{"name":"Department of Medicine and Division of Infectious Disease, Case Western Reserve University , Cleveland, Ohio ,","place":["USA"]},{"name":"Geriatric, Research, Education and Clinical Center (GRECC), Louis Stokes Cleveland VA Medical Center , Cleveland, Ohio ,","place":["USA"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7062-6920","authenticated-orcid":false,"given":"Yasin","family":"Abul","sequence":"additional","affiliation":[{"name":"Department of Medicine, The Warren Alpert Medical School of Brown University , Providence, Rhode Island ,","place":["USA"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1122-0071","authenticated-orcid":false,"given":"Kaleen N","family":"Hayes","sequence":"additional","affiliation":[{"name":"Transformative Health Systems Research to Improve Veteran Equity and Independence Center of Innovation (THRIVE COIN), Veterans Affairs Providence Health Care System , Providence, Rhode Island ,","place":["USA"]},{"name":"Department of Health Services, Policy & Practice, Brown University School of Public Health , Providence, Rhode Island ,","place":["USA"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6000-6859","authenticated-orcid":false,"given":"Stefan","family":"Gravenstein","sequence":"additional","affiliation":[{"name":"Transformative Health Systems Research to Improve Veteran Equity and Independence Center of Innovation (THRIVE COIN), Veterans Affairs Providence Health Care System , Providence, Rhode Island ,","place":["USA"]},{"name":"Department of Medicine, The Warren Alpert Medical School of Brown University , Providence, Rhode Island ,","place":["USA"]}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"286","published-online":{"date-parts":[[2026,8,27]]},"reference":[{"key":"2026091805312766700_ofag522-B1","doi-asserted-by":"crossref","first-page":"83","DOI":"10.15585\/mmwr.mm7406a2","article-title":"Interim estimates of 2024-2025 seasonal influenza vaccine effectiveness - 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