[Sciences] The TB-BCG vaccine, why I love vaccines and how certain vaccines give us immunity for life.


A couple of days ago, I had to have a physical exam for some administrative process. Among the different steps of the physical exam, I had to have a TB test. TB stands for tuberculosis. It is caused by an infectious agent, Mycobacterium tuberculosis. Mycobacterium genus contains some nasty germs inside including tuberculosis and foremost the one causing the leprosy. These are germs usually associated with poor hygiene but highly contagious.
M. tuberculosis is one of the particular bacteria that is very challenging to grow in cultures and until modern molecular biology technique, differential coloration using the Ziehl-fucsin technique (using malachite green) was used for identifying these germs from the population.
In the pre-antibiotic era, the only solution that was working at some point, as we called in Europe “sanatorium” consisting of fresh, high-altitude air with a good nutrition would help the “natural immunity” fight off the infection as well as strict law enforcement against “spitting in public area”. The arrival of streptomycin and the development of attenuated vaccines called “bacille de Calmette-Guerin” (thus the acronym BCG) and resulted in a huge decrease in cases of tuberculosis worldwide, leading to the closure sanatorium all over the world.
The BCG was a very popular vaccines and according my French immunization record, my last shot was dated from 1985, with a BCG test realized in 1993. This test, as seen in the picture, consist of an sub-cutaneous injection of tuberculin, a protein present on M. tuberculosis (both the virulent and BCG alike). These surface proteins act as a “passport” for our immune system, If the immune system recognize your plate is not valid, it will pull the foreign agent aside as if you fail to have valid document at the US Custom Border Protection booth. Its job is to kill and destroy anything that is not holding the right “passport”. This is were vaccines are important, they act as fake illegal aliens and train your immune system to recognize nasty agents. Thus, if one real threat appeared, it will able to immediately induce an appropriate response and neutralize the threat, but also insert into the server the useful information for newer generations of CBP agents to recognize the threat. This is the memory lymphocytes B-cells and T-cells that will persist more and less longer and these are the direct output of the vaccination process.
Thats bring me back to my injection, my body have for a good twenty years never in contact of such germ or such proteins and never get reminded about it. I got the test injected, it just took 24 hours to have a massive inflammation (hot, red, swollen and painful spot) to show that my whole immune system went completely on alert and identified a threat. This twenty years after encountering the agent.

I never had a chance to see a sanatorium in my life and tell us something about the impact of vaccines on public health. If such medical institutions and other diseases (like measles, mumps, rubella, whooping cough, polio, shingles…..) appears old or harmless, it is because vaccines have done a tremendous job in protecting us against these diseases. Do we still hear about sanatorium, iron lungs? No more, because vaccines worked and work to protect us. And because when everybody is vaccinated, the germs have no safe house to propagate and spread, this is what we call “herd immunity”. By protecting ourselves, we also protect those who cannot be protected because they are too young to get their first shot or face an immune compromised body due to various reasons.
However, the recent call of “anti-vaxxers” held a fallacious number of celebrities holding no credentials in biomedical sciences or public health, except holding abilities to talk with the gluteal muscles or known for a “ho-la-la” career have beem spearheading a movement to associate vaccines with death, autism and other conditions. This of course resulted in the recent increase in cases of measles and other diseases we considered eradicated (but were just hiding and kept at bay). It shows that deliberately breaching our protection and the “herd immunity” by standing on fallacious and pseudoscientific claims can have rapid and damaging effects on global health, including several cases of fatalities in various part of the world. You have to sit down and think about that some states like Oregon and Washington have vaccination rates plummeted so much that they went below some developing countries.
Vaccines work, vaccines are keeping us safe for diseases that were so devastating 50 years ago that vaccines were victim of their success and wiped out them from collective memories.   I love my vaccines and remind everyone to check your immunization records, be sure you have yours up-to-date. And foremost, vaccinates your damn kids, they will say thank you later in their life!



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