The strange case of bcg and covid-19: The verdict is still up in the air

Radha Gopalaswamy, Natarajan Ganesan, Kalamani Velmurugan, Vivekanandhan Aravindhan, Selvakumar Subbian

Research output: Contribution to journalArticlepeer-review

7 Scopus citations


COVID-19, caused by a novel coronavirus, SARS-CoV-2, contributes significantly to the morbidity and mortality in humans worldwide. In the absence of specific vaccines or therapeutics available, COVID-19 cases are managed empirically with the passive immunity approach and repurposing of drugs used for other conditions. Recently, a concept that bacilli Calmette–Guerin (BCG) vaccination could confer protection against COVID-19 has emerged. The foundation for this widespread attention came from several recent articles, including the one by Miller et al. submitted to MedRxiv, a pre-print server. The authors of this article suggest that a correlation exists between countries with a prolonged national BCG vaccination program and the morbidity/mortality due to COVID-19. Further, clinical BCG vaccination trials are currently ongoing in the Netherlands, Australia, the UK, and Germany with the hope of reducing mortality due to COVID-19. Although BCG vaccination helps protect children against tuberculosis, experimental studies have shown that BCG can also elicit a non-specific immune response against viral and non-mycobacterial infections. Here, we summarize the pros and cons of BCG vaccination and critically analyze the evidence provided for the protective effect of BCG against COVID-19 and highlight the confounding factors in these studies.

Original languageEnglish (US)
Article number612
Pages (from-to)1-9
Number of pages9
Issue number4
StatePublished - Dec 2020

All Science Journal Classification (ASJC) codes

  • Immunology
  • Pharmacology
  • Drug Discovery
  • Infectious Diseases
  • Pharmacology (medical)


  • BCG
  • COVID-19
  • Pandemic
  • SARS-CoV-2
  • Trained immunity
  • Tuberculosis


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