The Strange Case of BCG and COVID-19: The Verdict Is Still up in the Air

Vaccines — Open Access Journal
http://www.mdpi.com/journal/vaccines
(Accessed 17 Oct 2020)

 

Open Access Perspective
The Strange Case of BCG and COVID-19: The Verdict Is Still up in the Air
by Radha Gopalaswamy, Natarajan Ganesan, Kalamani Velmurugan, Vivekanandhan Aravindhan and Selvakumar Subbian
Vaccines 2020, 8(4), 612; https://doi.org/10.3390/vaccines8040612 – 16 Oct 2020
Abstract
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