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Using BCG vaccine to enhance non-specific protection of health care workers during the COVID-19 pandemic: a randomized controlled trial.

The Journal of infectious diseases

Authors: Anne Marie Rosendahl Madsen, Frederik Schaltz-Buchholzer, Sebastian Nielsen, Thomas Benfield, Morten Bjerregaard-Andersen, Lars Skov Dalgaard, Christine Dam, Sisse Bolm Ditlev, Gulia Faizi, Mihnaz Azizi, Zainab Nadhim Hameed, Isik Somuncu Johansen, Poul-Erik Kofoed, Tyra Grove Krause, Gitte Schultz Kristensen, Ellen Christine Leth Loekkegaard, Christian Backer Mogensen, Libin Mohamed, Emilie Sundhaugen Oedegaard, Anne Ostenfeld, Marcus Kjaer Soerensen, Christian Wejse, Mihai G Netea, Peter Aaby, Christine Stabell Benn

BACKGROUND: The BCG (Bacillus Calmette-Guérin) vaccine can induce non-specific protection against unrelated infections. We aimed to test the effect of BCG on absenteeism and health of Danish health care workers (HCWs) during the COVID-19 pandemic.

METHODS: A single-blinded randomized controlled trial including 1,221 HCWs from nine Danish hospitals. Participants were randomized 1:1 to standard dose BCG or placebo. Primary outcome was days of unplanned absenteeism. Main secondary outcomes were incidence of COVID-19, all-cause hospitalization, and infectious disease episodes.

RESULTS: There was no significant effect of BCG on unplanned absenteeism. Mean number of days absent per 1000 workdays was 20 in the BCG group and 17 in the placebo group (RR 1.23, 95% credibility interval: 0.98 to 1.53). BCG had no effect on incidence of COVID-19 or all-cause hospitalization overall. In secondary analyses BCG re-vaccination was associated with higher COVID-19 incidence (HR 2.47, 95% confidence interval (CI): 1.07 to 5.71), but also reduced risk of hospitalization (HR 0.28, CI: 0.09 to 0.86). The incidence of infectious disease episodes was similar between randomization groups (HR 1.09, CI: 0.96 to 1.24).

CONCLUSIONS: In this relatively healthy cohort of HCWs, there was no overall effect of BCG on any of the study outcomes.

© The Author(s) 2023. Published by Oxford University Press on behalf of Infectious Diseases Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

PMID: 37774494

Participating cluster members