{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,23]],"date-time":"2026-08-23T14:29:24Z","timestamp":1787495364368,"version":"build-2736575974"},"reference-count":25,"publisher":"Springer Science and Business Media LLC","issue":"1","license":[{"start":{"date-parts":[[2021,5,26]],"date-time":"2021-05-26T00:00:00Z","timestamp":1621987200000},"content-version":"tdm","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0"},{"start":{"date-parts":[[2021,5,26]],"date-time":"2021-05-26T00:00:00Z","timestamp":1621987200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0"}],"content-domain":{"domain":["link.springer.com"],"crossmark-restriction":false},"short-container-title":["Sci Rep"],"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:p>The coronavirus disease of 2019 (COVID-19) has caused a global pandemic and led to nearly three million deaths globally. As of April 2021, there are still many countries that do not have COVID-19 vaccines. Before the COVID-19 vaccines were developed, some evidence suggested that an influenza vaccine may stimulate nonspecific immune responses that reduce the risk of COVID-19 infection or the severity of COVID-19 illness after infection. This study evaluated the association between influenza vaccination and the risk of COVID-19 infection. We conducted a retrospective cross-sectional study with data from July 1, 2019, to June 30, 2020 with the Claims data from Symphony Health database. The study population was adults age 65 years old or older who received influenza vaccination between September 1 and December 31 of 2019. The main outcomes and measures were odds of COVID-19 infection and severe COVID-19 illness after January 15, 2020. We found the adjusted odds ratio (aOR) of COVID-19 infection risk between the influenza-vaccination group and no-influenza-vaccination group was 0.76 (95% confidence interval (CI), 0.75\u20130.77). Among COVID-19 patients, the aOR of developing severe COVID-19 illness was 0.72 (95% CI, 0.68\u20130.76) between the influenza-vaccination group and the no-influenza-vaccination group. When the influenza-vaccination group and the other-vaccination group were compared, the aOR of COVID-19 infection was 0.95 (95% CI, 0.93\u20130.97), and the aOR of developing a severe COVID-19 illness was 0.95 (95% CI, 0.80\u20131.13). The influenza vaccine may marginally protect people from COVID-19 infection.<\/jats:p>","DOI":"10.1038\/s41598-021-90068-y","type":"journal-article","created":{"date-parts":[[2021,5,26]],"date-time":"2021-05-26T06:04:00Z","timestamp":1622009040000},"update-policy":"https:\/\/doi.org\/10.1007\/springer_crossmark_policy","source":"Crossref","is-referenced-by-count":40,"title":["Influenza vaccination and the risk of COVID-19 infection and severe illness in older adults in the United States"],"prefix":"10.1038","volume":"11","author":[{"given":"Kelly","family":"Huang","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Shu-Wen","family":"Lin","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Wang-Huei","family":"Sheng","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4597-4859","authenticated-orcid":false,"given":"Chi-Chuan","family":"Wang","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"297","published-online":{"date-parts":[[2021,5,26]]},"reference":[{"key":"90068_CR1","unstructured":"World Health Organization. WHO Coronavirus Disease (COVID-19) Dashboard, https:\/\/covid19.who.int\/ (2020)."},{"key":"90068_CR2","first-page":"159","volume":"82","author":"P Wu","year":"2021","unstructured":"Wu, P. et al. COVID-19 patients with recent influenza A\/B infection: A retrospective study. J. Infect. 82, 159\u2013198 (2021).","journal-title":"J. Infect."},{"key":"90068_CR3","doi-asserted-by":"publisher","first-page":"1364","DOI":"10.1016\/j.chest.2020.05.580","volume":"158","author":"L Jehi","year":"2020","unstructured":"Jehi, L. et al. Individualizing risk prediction for positive coronavirus disease 2019 testing: results from 11,672 patients. Chest 158, 1364\u20131375 (2020).","journal-title":"Chest"},{"key":"90068_CR4","doi-asserted-by":"publisher","first-page":"471","DOI":"10.3390\/vaccines8030471","volume":"8","author":"M Noale","year":"2020","unstructured":"Noale, M. et al. The association between influenza and pneumococcal vaccinations and SARS-Cov-2 infection: Data from the EPICOVID19 web-based survey. Vaccines (Basel) 8, 471 (2020).","journal-title":"Vaccines (Basel)"},{"key":"90068_CR5","doi-asserted-by":"publisher","first-page":"14","DOI":"10.21101\/cejph.a6573","volume":"29","author":"B Erismis","year":"2021","unstructured":"Erismis, B. et al. Annual influenza vaccination effect on the susceptibility to COVID-19 infection. Cent. Eur. J. Public Health. 29, 14\u201317 (2021).","journal-title":"Cent. Eur. J. Public Health."},{"key":"90068_CR6","doi-asserted-by":"crossref","unstructured":"Zanettini, C. et al. Influenza Vaccination and COVID19 Mortality in the USA. medRxiv : the preprint server for health sciences, 2020.2006.2024.20129817, doi:10.1101\/2020.06.24.20129817 (2020).","DOI":"10.1101\/2020.06.24.20129817"},{"key":"90068_CR7","doi-asserted-by":"publisher","first-page":"535","DOI":"10.3390\/vaccines8030535","volume":"8","author":"M Amato","year":"2020","unstructured":"Amato, M. et al. Relationship between influenza vaccination coverage rate and COVID-19 outbreak: An Italian ecological study. Vaccines (Basel) 8, 535 (2020).","journal-title":"Vaccines (Basel)"},{"key":"90068_CR8","first-page":"bmjebm-2020-111","volume":"11","author":"G Fink","year":"2020","unstructured":"Fink, G. et al. Inactivated trivalent influenza vaccine is associated with lower mortality among Covid-19 patients in Brazil. BMJ Evid. Based Med. 11, bmjebm-2020-111549 (2020).","journal-title":"BMJ Evid. 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COVID-19 and the elderly: Insights into pathogenesis and clinical decision-making. Aging Clin. Exp. Res. 32, 1599\u20131608 (2020).","journal-title":"Aging Clin. Exp. Res."},{"key":"90068_CR12","unstructured":"Centers for Disease Control and Prevention. Older Adults. https:\/\/www.cdc.gov\/coronavirus\/2019-ncov\/need-extra-precautions\/older-adults.html (2020)."},{"key":"90068_CR13","unstructured":"COVID-19 Research Database. https:\/\/covid19researchdatabase.org\/"},{"key":"90068_CR14","unstructured":"Centers for Disease Control and Prevention. Key Facts About Seasonal Flu Vaccine, https:\/\/www.cdc.gov\/flu\/prevent\/keyfacts.htm (2020)."},{"key":"90068_CR15","unstructured":"Centers for Disease Control and Prevention. IIS: NDC Lookup Crosswalk, https:\/\/www2a.cdc.gov\/vaccines\/iis\/iisstandards\/vaccines.asp?rpt=ndc (2020)."},{"key":"90068_CR16","unstructured":"Ball, R. 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The original Article has been corrected.","order":6,"name":"change_details","label":"Change Details","group":{"name":"ArticleHistory","label":"Article History"}},{"value":"The authors declare no competing interests.","order":1,"name":"Ethics","group":{"name":"EthicsHeading","label":"Competing interests"}}],"article-number":"11025"}}