How a vaccine against tuberculosis a century-old could help to combat the novel coronavirus


(CNN) — While researchers are struggling to find new medicines and vaccines for covid-19, a vaccine that has more than a century old has attracted the interest of some researchers.

The vaccine Bacillus Calmette-Guerin (BCG), which was first developed to fight tuberculosis, is being studied in clinical trials around the world as a way to fight the new coronavirus.

Tuberculosis and infection by covid-19 are two very different diseases: to start with, the first is caused by a type of bacteria, while covid-19 is caused by a virus. But the BCG vaccine could help people develop immune responses to other things in addition to tuberculosis, causing “off-target effects,” according to Dr. Denise Faustman, director of immunobiology at Massachusetts General Hospital and associate professor of medicine at Harvard Medical School.

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“In other words, in the format of a clinical trial, people began to get a positive benefit of receiving the vaccine had nothing to do with tuberculosis,” he said.

Faustman has studied how the BCG vaccine affects people with type 1 diabetes for many years. She is interested in how their off-target effects change the immune system in a beneficial way for people with autoimmune diseases such as type 1 diabetes.

Although the exact mechanism for these off-target effects of the BCG vaccine is not clear, it is believed that the vaccine can cause a boost non-specific immune response.

There are currently no vaccines or treatments approved by the Food and Drug Administration of United States for the new coronavirus. Even if you have the hope that the BCG vaccine will prove to be effective against covid-19, as with any of the treatments and vaccines in development, Dr. William Schaffner, infectious disease specialist at the Faculty of Medicine of Vanderbilt University, admits that the concept is a little unconventional.

“I believe that the BCG vaccine is something equivalent to a pass Hail Mary,” said Schaffner. “It’s a concept so original that one would like to be optimistic, but we’ll have to wait and see.”

Several countries around the world are starting human clinical trials to evaluate the efficacy of the BCG vaccine, such as Australia and the Netherlands.

Faustman and her colleagues are preparing for the trials in Boston, where she is currently under a review process of several steps. Once approved, she and the members of your team expect to enroll about 4,000 health workers in the trial.

Test the first experimental vaccine anticoronavirus 0:28

The vaccine has been available for more than 100 years and has proven to be relatively safe, ” said Faustman.

“BCG is presented by the World Health organization as the vaccine safest ever developed in the world,” he said. “More than 3,000 million people loa have been received”.

Although several countries, including the united States, not given regularly to the BCG vaccine, it is still widely used in developing countries.

Researchers have attempted to analyse whether these countries with the regular administration of the BCG vaccine have lower rates of mortality related to covid-19. A study conducted by researchers in New York found an association between the policy of universal BCG vaccination in the countries and the reduction of the morbidity and lethality of Covid-19. The study has not been peer-reviewed nor published in a medical journal.

But, why China has had a high morbidity and lethality by covid-19 although a policy universal BCG from the 1950s? The study said China had a policy weakened during the Cultural Revolution in the 1960s and 1970s, which could have created “a group of potential hosts that would be affected and propagate covid-19”.

In addition, China has not been a steep increase in its curve compared to other countries without universal policies, such as Italy, Spain and the united States, ” said Faustman. He also added that different BCG vaccine strains may have different rates of effectiveness.

One of the main limitations of this study is to compare data from different countries, who have different time schedules for covid-19 and different capacities to perform testing.

“It was a comparison of 30,000 feet of the occurrence of infections by covid-19 in countries that used intensively the BCG vaccine and those who do not,” said Vanderbilt’s Schaffner. “We should not draw any conclusion from that, because … the countries are very different. And, therefore, there can be many other reasons that determine the frequency with which covid has happened in those countries.

“The study provides further stimulus to research more specific, such as clinical trials that will be carried out”.

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