2021 marks the hundredth year of the administration of the first dose of the BCG vaccine. The vaccine, which was invented by Albert Calmette and Camille Guerin at the Institut Pasteur de Lille, is primarily used to protect children from tuberculosis.
However, the vaccine has also shown a protective effect against other diseases, which is why trials are being conducted all over the world to test whether it could be effective against Covid-19.
According to Dr Camille Locht, research director of Inserm at the Institut Pasteur de Lille, the mechanism of the BCG vaccine has to do with the innate immune system.
"The BCG is able to train the cells of the innate immune system to make them more fit and active to fight against other diseases. This is why we think that by training the immune system with BCG, it will have a protective effect against organisms that have nothing to do with tuberculosis or BCG," Dr Locht told RFI.
This is the result of the presence of a live organism in the BCG vaccine. "Usually, vaccines are given as inactivated, dead organisms but in the case of the BCG, the vaccine has to be 'live' and multiply for a certain time in the organism that has been vaccinated to have its effect," Dr Locht says.
He adds that this versatile vaccine is also used as a medication against bladder cancer, preventing the recurrence of the disease if given early in the treatment.
"Due to the non-specific, protective effect offered by the BCG vaccine against other infectious diseases, it was obvious to think about its potential use against Covid-19."
The vaccine has proved its worth over the past 100 years in the fight against TB in children.
"It's the world's most widely used vaccine with more than three billion doses given to protect children against TB," Dr Locht says.
Creating this vaccine was a formidable challenge for its French inventors Albert Calmette and Camille Guerin who conducted 231 'passages' to attenuate the bovine tuberculosis bacillus from 1908 to 1921 at the Institut Pasteur de Lille.
The process of attenuation, which involved the use of potatoes and ox bile in the culture medium, survived the First World War before it became ready for use in humans.
Given the arduous task of developing the vaccine, it is only fair that the BCG or Bacillus Calmette-Guerin carries the name of its inventors.