{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,28]],"date-time":"2026-07-28T09:07:02Z","timestamp":1785229622609,"version":"3.55.0"},"reference-count":30,"publisher":"Public Library of Science (PLoS)","issue":"5","license":[{"start":{"date-parts":[[2025,5,13]],"date-time":"2025-05-13T00:00:00Z","timestamp":1747094400000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"The National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University","award":["2021KFJJ06"],"award-info":[{"award-number":["2021KFJJ06"]}]},{"name":"Hunan Provincial Natural Foundation of China","award":["2021JJ30040"],"award-info":[{"award-number":["2021JJ30040"]}]}],"content-domain":{"domain":["www.plosone.org"],"crossmark-restriction":false},"short-container-title":["PLoS One"],"abstract":"<jats:sec id=\"sec018\">\n<jats:title>Background<\/jats:title>\n<jats:p>The Bacillus Calmette-Gu\u00e9rin (BCG) vaccine has shown potential non-specific protection against infectious diseases through \u201ctrained immunity\u201d, which may offer cross-protection against viral infections. However, there is no consensus on whether BCG vaccination could prevent COVID-19 or reduce its symptoms.<\/jats:p>\n<\/jats:sec>\n<jats:sec id=\"sec019\">\n<jats:title>Methods<\/jats:title>\n<jats:p>PubMed, Cochrane Library, Embase and Web of Science were searched for randomized controlled trials on BCG vaccination and COVID-19 prevention, covering studies from the inception of each database to 2 May 2024. We included studies where participants, not infected with COVID-19, were vaccinated with BCG or placebo. We excluded non-randomized trials, studies without full texts, unrelated interventions, and those not reporting relevant outcomes. Clinical data on COVID-19 infection, severity, hospitalization, mortality, and other adverse events, were extracted and analyzed. The DerSimonian\u2013Laird random-effects model and the Cochrane Collaboration\u2019s risk of Bias Tool were used for analysis and risk of bias assessment.<\/jats:p>\n<\/jats:sec>\n<jats:sec id=\"sec020\">\n<jats:title>Results<\/jats:title>\n<jats:p>A total of 12 RCTs involving 18,086 patients were finally included. For the prophylactic effect of BCG on COVID-19, pooled results showed no statistically significant difference between BCG and placebo (pooled RR 1.02; 95%CI: 0.91\u20131.14). There was no statistically significant difference between non-health care workers (pooled RR 0.91; 95%CI: 0.67\u20131.24) and health care workers (pooled RR 1.03; 95%CI: 0.93\u20131.15). Regarding COVID-19 severity, no significant difference were found for asymptomatic (pooled RR 1.18; 95%CI: 0.81\u20131.72), mild to moderate (pooled RR 0.99; 95%CI: 0.84\u20131.17), severe COVID-19 (pooled RR 1.25; 95%CI: 0.92\u20131.70), hospitalization (pooled RR 0.93; 95%CI: 0.58\u20131.50) or all-cause mortality (pooled RR 0.60; 95%CI: 0.18\u20131.95) between BCG and placebo groups. Subgroup analysis also showed no significant difference between BCG and placebo in non-health care workers or health care workers.<\/jats:p>\n<\/jats:sec>\n<jats:sec id=\"sec021\">\n<jats:title>Conclusions<\/jats:title>\n<jats:p>Vaccination of BCG could not effectively prevent COVID-19 infection or decrease COVID-19 symptoms both in non-health care workers and health care workers.<\/jats:p>\n<\/jats:sec>","DOI":"10.1371\/journal.pone.0321511","type":"journal-article","created":{"date-parts":[[2025,5,13]],"date-time":"2025-05-13T19:32:46Z","timestamp":1747164766000},"page":"e0321511","update-policy":"https:\/\/doi.org\/10.1371\/journal.pone.corrections_policy","source":"Crossref","is-referenced-by-count":10,"title":["Efficacy of BCG vaccination against COVID-19 in health care workers and non-health care workers: A meta-analysis of randomized controlled 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