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Int J Environ Res Public Health
. 2020 Aug 3;17(15):E5589.
doi: 10.3390/ijerph17155589.
BCG Vaccination and Mortality of COVID-19 across 173 Countries: An Ecological Study
Mitsuyoshi Urashima 1 , Katharina Otani 1 2 , Yasutaka Hasegawa 1 3 , Taisuke Akutsu 1
Affiliations
- PMID: 32756371
- DOI: 10.3390/ijerph17155589
Abstract
Ecological studies have suggested fewer COVID-19 morbidities and mortalities in Bacillus Calmette-Gu?rin (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-more than four months after declaration of the pandemic-the 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. 'Urban population (%)' and 'insufficient physical activity (%)' 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 ≥ 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.
Keywords: BCG; Bacillus Calmette–Gu?rin; COVID-19; SARS-CoV-2; coronavirus disease 2019; ecological study; morbidity; mortality; urbanization; vaccination.