Research ArticleCORONAVIRUS

Mandated Bacillus Calmette-Guérin (BCG) vaccination predicts flattened curves for the spread of COVID-19

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Science Advances  05 Aug 2020:
Vol. 6, no. 32, eabc1463
DOI: 10.1126/sciadv.abc1463

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  • Is nitric oxide the underlying effector molecule for BCG mediated protection against Covid-19?
    • Shawn J. Green, Scientist, Lindquist Institute at Harbor-UCLA Medical Center

    The clinical outcomes of inhaled nitric oxide gas and BCG immunotherapy may offer insight as to coronavirus’ vulnerability. Both approaches that are intended to restore pulmonary function and slow viral replication may be working through the same effector molecule, nitric oxide.

    Several medical device companies have received FDA’s blessing for emergency expanded access to offer inhaled nitric oxide gas for treating Covid-19. During the 2003 SARS outbreak, inhalation of nitric oxide improved lung oxygenation and shortened the length of ventilatory support (1). Aside from improving lung function, nitric oxide also showed direct antiviral activity (2).

    Trials are also underway to test BCG’s ability to rev-up the innate immunity with the hope to provide protection against SARS-CoV-2. BCG is a weakened, live bacterium, bacillus Calmette-Guérin that is a distant relative of the pathologic mycobacterium that cause leprosy and tuberculosis, TB. BCG has been administrated for decades to newborns in many countries as a vaccine against TB with inconsistent outcomes. However, several countries have observed nearly a 50% reduction in mortality in children vaccinated with BCG, an effect that is too big to be explained by protection against TB alone (3). There is also suggestive evidence that countries with a BCG policy in place had slower growth of both cases and deaths resulting from Covid-19 as compared to countries that do not vaccinate with BCG as suggeste...

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    Competing Interests: None declared.
  • RE: BCG vaccine plausible protection in COVID19: We can’t ignore M. tuberculosis burden
    • Ranjeet Singh Mahla, Senior Research Fellow, Indian Institute of Science Education and Research (IISERB) Bhopal

    Dear Editor,

    In their observational study, Berg et al. (1) have shown an inverse correlation between mandatory BCG vaccination and COVID19 burden. Flattening of the COVID19 incidence curve during the first 30 days since the country reported official index cases, the underlying confounders limit this observation. The underlying non-pharmaceutical measures, such as mandatory face masking, enforced lockdown, and movement restriction, are country-specific standards—more than BCG vaccination immune protection, country specific pharmaceutical and non pharmaceutical measures have impacted COVID19 burden. If BCG vaccination protects against COVID19, nations with mandatory BCG vaccination must experience a low COVID19 burden. That is not the scenario. Except for the USA, the other countries severely impacted by COVID19, such as India, Brazil, South Africa, and Russia, adopted to mandatory BCG vaccination policy have no beneficiary outcomes for the experienced unprecedented mortalities and morbidities caused by SARS-Cov2 infection.

    World Health Organization (WHO) does not recommend using the BCG vaccine in COVID19 management, as there is no direct evidence that BCG vaccination protects against COVID19 (2). In high-risk settings where the tuberculosis burden is high, every newborn gets BCG vaccine administration to protect disseminated form of tuberculosis. If left untreated, the disease is many folds deadlier than COVID19. As World experienced a new pandemic, tubercu...

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    Competing Interests: None declared.

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