An old tuberculosis vaccine, known to boost the immune system, failed to prevent health workers from contracting Covid, scientists reported Thursday.
But the trial was shorter and smaller than originally planned, and the researchers said the results did not rule out other potential benefits associated with the vaccine known as bacillus Calmette-Guérin BCG. .
of A study published in The New England Journal of Medicine, It was the largest clinical trial of a vaccine’s potential to protect against Covid infection. BCG was developed in the early 1900s to combat tuberculosis, but since then it has also been shown to confer protection against other illnesses, including respiratory diseases.
The healthcare worker trial began in March 2020, early in the pandemic. At the time, there was no effective treatment for Covid, and a new vaccine against the highly contagious disease seemed a distant fantasy. The hope was that old vaccines might be reused to save lives.
Six months after vaccination with BCG, however, there was no significant difference between the two groups of healthcare workers: 14.7% of those vaccinated with BCG developed symptomatic Covid infection, whereas saline 12.3% of those who received placebo injections became ill.
Five participants in each group were hospitalized and one participant who received placebo died. The difference was not statistically significant.
The rapid development of mRNA vaccines made it impossible to complete the BCG trial as designed, as healthcare workers were among the first in line to obtain newly available mRNA shots.
The goal of the BCG trial was to follow 10,000 participants from five countries (Australia, the Netherlands, Spain, the UK, and Brazil) for 12 months, but the new paper found that 4,000 adults were followed for 6 months. only been reported.
An mRNA vaccine is an “absolute miracle of modern science,” said Dr. Nigel Curtis, the trial’s principal investigator and professor of pediatric infectious diseases at the University of Melbourne, Australia. “But from a trial standpoint, it was pretty disastrous.”
Larger trials were needed to see if the vaccine would prevent not just infections, but hospitalizations and deaths from Covid.
Vaccines are still widely used in developing countries where many babies die before their first birthday. Scientists have found that BCG vaccination reduces infant mortality. appears to reduce the incidence of disease in
“The conclusion of our study that BCG does not protect health care workers from mild or moderate Covid is true,” Dr. Curtis said.
But it could still be promising, he added. BCG is still a very important concept for infants. ”
Additional analyzes of data collected from vaccinated HCWs are ongoing. Dr. Curtis said the vaccine’s efficacy may vary depending on the virus or bacteria it fights.
The BCG vaccine contains live modified bacteria that have been cultured for decades in laboratories around the world, introducing mutations that have led to many strains. strains and inoculation methods may lead to inconsistent results in other studies.
One of the most successful so far is Small study in adults with type 1 diabetes I received multiple BCG shots before the pandemic to improve my blood sugar levels and reduce infections.
That study found that those who received BCG had far fewer Covid infections than those who received placebo injections.
