{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,19]],"date-time":"2026-06-19T18:30:43Z","timestamp":1781893843203,"version":"3.54.5"},"reference-count":31,"publisher":"MDPI AG","issue":"15","license":[{"start":{"date-parts":[[2020,8,3]],"date-time":"2020-08-03T00:00:00Z","timestamp":1596412800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["IJERPH"],"abstract":"<jats:p>Ecological studies have suggested fewer COVID-19 morbidities and mortalities in Bacillus Calmette\u2013Gu\u00e9rin (BCG)-vaccinated countries than BCG-non-vaccinated countries. However, these studies obtained data during the early phase of the pandemic and did not adjust for potential confounders, including PCR-test numbers per population (PCR-tests). Currently\u2014more than four months after declaration of the pandemic\u2014the BCG-hypothesis needs reexamining. An ecological study was conducted by obtaining data of 61 factors in 173 countries, including BCG vaccine coverage (%), using morbidity and mortality as outcomes, obtained from open resources. \u2018Urban population (%)\u2019 and \u2018insufficient physical activity (%)\u2019 in each country was positively associated with morbidity, but not mortality, after adjustment for PCR-tests. On the other hand, recent BCG vaccine coverage (%) was negatively associated with mortality, but not morbidity, even with adjustment for percentage of the population \u2265 60 years of age, morbidity, PCR-tests and other factors. The results of this study generated a hypothesis that a national BCG vaccination program seems to be associated with reduced mortality of COVID-19, although this needs to be further examined and proved by randomized clinical trials.<\/jats:p>","DOI":"10.3390\/ijerph17155589","type":"journal-article","created":{"date-parts":[[2020,8,3]],"date-time":"2020-08-03T06:16:47Z","timestamp":1596435407000},"page":"5589","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":46,"title":["BCG Vaccination and Mortality of COVID-19 across 173 Countries: An Ecological Study"],"prefix":"10.3390","volume":"17","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-7395-5831","authenticated-orcid":false,"given":"Mitsuyoshi","family":"Urashima","sequence":"first","affiliation":[{"name":"Division of Molecular Epidemiology, The Jikei University School of Medicine, Tokyo 105-8461, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2322-3405","authenticated-orcid":false,"given":"Katharina","family":"Otani","sequence":"additional","affiliation":[{"name":"Division of Molecular Epidemiology, The Jikei University School of Medicine, Tokyo 105-8461, Japan"},{"name":"Advanced Therapies Innovation Department, Siemens Healthcare K.K., Tokyo 141-8644, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yasutaka","family":"Hasegawa","sequence":"additional","affiliation":[{"name":"Division of Molecular Epidemiology, The Jikei University School of Medicine, Tokyo 105-8461, Japan"},{"name":"Hitachi, Ltd. Research &amp; Development Group, Tokyo 185-8601, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Taisuke","family":"Akutsu","sequence":"additional","affiliation":[{"name":"Division of Molecular Epidemiology, The Jikei University School of Medicine, Tokyo 105-8461, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2020,8,3]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"2211","DOI":"10.1016\/S0140-6736(06)69895-4","article-title":"Estimation of potential global pandemic influenza mortality on the basis of vital registry data from the 1918-20 pandemic: A quantitative analysis","volume":"368","author":"Murray","year":"2006","journal-title":"Lancet"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"2534","DOI":"10.1056\/NEJMsa2011686","article-title":"Hospitalization and mortality among black patients and white patients with Covid-19","volume":"382","author":"Burton","year":"2020","journal-title":"N. 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