As the incurably naive that I am, I am still surprised when I realize that many people live with their backs turned to science. I am not referring here to the fact that they believe that science cannot offer answers to the fundamental questions of human existence (which it can, even if the ones it offers are not pleasant and require a lot of effort to understand them), but rather that they live backwards even to the proven benefits of science.
This is the case of the many people who have stopped believing or have never believed in the efficacy of vaccines, which has caused an upturn in diseases that were believed to be overcome.
For this reason, still determined to believe that what I write can be useful, today I want to talk about the unsuspected benefits discovered for one of the oldest vaccines in the world: tuberculosis. This vaccine was invented by the French physician Albert Calmette and his assistant Camille Guérin at the beginning of the 20th century.
The vaccine consists of a live bacillus that is the cause of bovine tuberculosis. This bacillus is as virulent as the human bacillus and causes severe tuberculosis in both humans and cattle. However, Calmette and Guérin set out to grow the bacillus in the laboratory, under various conditions, to try to get less virulent varieties that could be used as vaccines. They found that the bacillus could be cultivated in a kind of potato and glycerin-based soup, in which it lost part of its virulence. After subculturing the bacillus 239 times and analyzing its virulent properties for thirteen years, progressively selecting the least virulent bacilli, Calmette and Guérin achieved the variety of bacillus that bears their name (with the initials: BCG), which is much less virulent than the original and has been used as a vaccine against tuberculosis in hundreds of millions of people around the world.
The efficacy of this vaccine against meningitis tuberculosis is very high, but not so much against pulmonary tuberculosis. However, the vaccine has been used continuously since 1921. It is the oldest vaccine still in use, in the absence of a more effective one. Newer vaccines rarely include living organisms, however attenuated in virulence they may be, as there is always a risk that these organisms may mutate back to their original virulence and cause disease. For this reason, current vaccines consist of inert molecular components, isolated from a microorganism, against which the immune system reacts and generates protection against the entire microorganism. The vaccine BCG is an exception.
Perhaps because it is exceptional, the scientific community in recent years has been interested in studying more closely the health of people vaccinated with the bacillus. BCG. What has been discovered is surprising and concerns not only the protection that the vaccine confers against various forms of tuberculosis, but other unsuspected health benefits.
We can start with the impressive discovery that people with tuberculosis had a lower incidence of cancer. This led to another discovery, that the vaccine is quite effective in fighting bladder cancer and today more than three million bladder cancer patients have been successfully treated with direct injections of this vaccine into the bladder, which have been used since 1977. This vaccine is, therefore, one of the first immunotherapy strategies used against cancer. The mechanisms by which it works are not yet known with certainty. It is believed, however, that the fact that the vaccine contains a living organism stimulates the immune system in ways that vaccines made only of inert molecules cannot achieve.
The vaccine BCG It also produces benefits against allergic and autoimmune diseases. Among the first we have asthma, a disease that can sometimes lead to death. Well, those vaccinated with BCG they are protected from the development of asthma and also from other allergic diseases. The reason for this effect is better understood and is related to the development of the immune system in childhood, which can be negatively affected in environments with low levels of microorganisms, that is, excessively hygienic. This is what has been called the “hygiene hypothesis” which attempts to explain the clear increase in allergies in recent years in developed countries. Apparently, an excess of hygiene produces unwanted effects on the immune system, which, lacking real threats, reacts inappropriately to innocuous stimuli, such as pollen grains. The vaccine BCGbeing formed by a living microorganism, would correctly “educate” the developing immune system and prevent it from investing unnecessary energy in fighting non-existent enemies.
A similar protective effect of the vaccine has been observed against autoimmune diseases, in which the immune system makes the serious mistake of attacking the body’s own cells, mistaking them for enemies. These diseases include some of the severity of multiple sclerosis and also type 1 diabetes mellitus, a disease caused by the immune system’s attack on the insulin-producing beta cells of the pancreas. Elimination of these cells leads to the inability to manufacture insulin and consequently to diabetes.
The aforementioned are not the only beneficial effects of this amazing vaccine. Research continues and promises to reveal interesting secrets about the functioning of the immune system and its relationship with cancer and other diseases. As on so many other occasions it seems like a matter of magic, but it is just a matter of pure science.
Hashizume A. el al (2018). Enhanced expression of PD-L1 in non-muscle-invasive bladder cancer after treatment with Bacillus Calmette-Guérin. Oncotarget. 2018 Sep 25;9(75):34066-34078. doi: 10.18632/oncotarget.26122. (2) BCG, it can actually heal anything. Science and life 1214.
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