Link between BCG vaccination and Covid-19 mortality

US, WASHINGTON (ORDO NEWS) — Massive tuberculosis vaccination may explain the reduced mortality from coronavirus in some countries. However, there are exceptions to this rule that scientists have not yet figured out. In addition, the biochemical mechanisms of such protection are not known.

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A group of scientists from the Technological University of New York reported that mortality from Covid-19 infection is inversely correlated with the prevalence of tuberculosis vaccination. An article about this is available in the MedRxiv preprint archive.

The Covid-19 pandemic spanned almost the entire world, but its development varies by country. This may be due to accounting methods and conditions for testing patients, cultural standards, strict quarantine measures and the quality of medical infrastructure.

In a new article, scientists suggest that differences may also be affected by national BCG vaccine policies.

BCG is a safe and inexpensive tuberculosis vaccine made from a weakened strain of live bacteria Mycobacterium bovis. It also has proven effectiveness in the fight against other diseases caused by mycobacteria: in particular, with leprosy and Buruli ulcer.

According to American scientists, BCG vaccination gives the body certain advantages in the fight against coronavirus. Comparing tuberculosis vaccination policies in different countries, researchers found that countries without a universal vaccination policy (such as the Netherlands, Italy, and the United States) are much more affected by a pandemic than countries where the vaccine has been used for a long time and regularly.

Among the latter, researchers mention Brazil, where universal tuberculosis vaccination has been used since 1920, and Japan: BCG has been widely used there since the late 1940s. At the same time, states in which a universal vaccination policy was formed relatively recently (for example, Iran, where the widespread use of BCG began only in 1984), have a particularly high mortality rate among the elderly population.

The assumption made in the article can explain the low mortality rate in some poor states – for example, in the post-Soviet space and in Eastern Europe. It is worth noting that in many regions with a low level of per capita income so far there has not been a single death from Covid-19.

However, the authors took into account the fact that this may be due to poor quality of diagnostics or intentional underestimation of statistical indicators, therefore they excluded such “anomalies” from their study.

However, the final conclusion about the effectiveness of the BCG vaccine is too early to draw. Firstly, an article by researchers from the Technological University of New York has not yet been reviewed and has not been accepted by any reputable scientific publication.

Secondly, clinical trials are needed to confirm the efficacy of the TB vaccine. Now such a study is being started by scientists from the Murdoch Children’s Research Institute in Melbourne.

The work of American researchers also does not explain why the correlation between widespread BCG vaccination and reduced mortality from coronavirus has not been observed in China, where long-term immunization has been used.

In addition, many scientists question the fact that a childhood vaccination can help older people get the disease. Tuberculosis protection is fully operational for 10-15 years, and its effectiveness after this period has not been precisely determined.

At the same time, this fact alone is not enough to completely destroy the theoretical constructs about the role of BCG: for example, there is an earlier study in which Native Americans vaccinated in the 1930s found effective anti-tuberculosis protection 60 years after vaccination.

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The article is written and prepared by our foreign editors from different countries around the world – material edited and published by Ordo News staff in our US newsroom press.