The vaccine against tuberculosis (tb) is studied against the coronavirus

Le vaccin contre la tuberculose est étudié contre le coronavirus

Photo: Rodger Bosch Archive Agence France-Presse

The vaccine BCG (bacillus Calmette and Guérin) exists since tens of years, and scientists have found over time that it seems to generate a protection which goes beyond the single tb.

Researchers around the world are trying to determine if the vaccine against tuberculosis could confer a certain protection against SARS-CoV-2, the virus responsible for the disease coronavirus (COVID-19).

Studies on this subject are, in particular, carried out in France, Spain, the netherlands and Australia.

The vaccine BCG (bacillus Calmette and Guérin) exists since tens of years, and scientists have found over time that it seems to generate a protection which goes beyond the single tb.

“There are results that come from both experimental studies in animals and studies in humans, smaller in scale until now, that suggest that vaccination with the BCG vaccine could strengthen the immune system (…) to help respond more effectively to other infections, so bacterial infections and viral infections that are not necessarily related to the mycobacteria that cause tb,” explained Marie-Claude Rousseau, a professor and epidemiologist at the Institut national de la recherche scientifique (INRS) who studied the OCG for the past fifteen years.

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We are talking here about the phenomenon of “immunity-driven,” which was discovered a few years ago, said Ms. Rousseau.

The immune cells that represent the first line of defense of the body appear to undergo changes that make them more effective when they encounter an infectious agent, even if it is not one of tuberculosis.

“In most cases, the vaccines will lead to the production of specific antibodies against the virus for which they were designed, said Ms. Rousseau. In the case of BCG, the vaccine leads to an increase of the cellular immune response and to an increase in the humoral immune response.

“The cellular immune response, it is really the activation of the first line of defense of the immune system, and this response-there does not work with antibodies that are specific to them. It works by the activation of cells that are involved in the immune response and non-specific.”

Studies conducted in developing countries, for example, have found a lower mortality rate in children who had been vaccinated by the BCG.

Two reports from the world Health Organization have concluded in recent years with a protective effect of BCG, especially as the mortality rates in the developing countries is mainly linked to infectious diseases.

“It is obvious a little indirect, which is beginning to be a little convincing, said Ms. Rousseau. Different studies (…) suggest (…) that there might be a protection against different viral infections.”

The clinical trials will tell us in the short term if the fact of giving this vaccine to health care workers or older people to help prevent infection or to decrease the severity of the disease, she concluded.

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