In the early days of the COVID-19 pandemic, when prevention seemed light years away, many scientists began testing to see whether a tuberculosis vaccine developed in the early 1900s could protect people by strengthening the immune system. could.
The Bacillus-Calmette-Guerin vaccine has long been known to have widespread effects on the immune system, and is still given to infants in developing countries and countries where TB is prevalent.
Scientists observed several years ago that vaccines train the immune system to respond to a variety of infectious diseases, including viruses, bacteria and parasites, and reduce infant mortality.
As new threats such as monkeypox and polio re-emerge and the coronavirus continues to evolve, the ability of older vaccines to provide universal protection against infectious diseases has sparked renewed interest among scientists.
Now the results of clinical trials conducted during the pandemic are coming in, and the findings, while mixed, are encouraging.
The latest results, published Monday in Cell Medicine Reports, come from a trial that began before Covid-19 emerged. It was designed to see whether multiple BCG injections could benefit people with type 1 diabetes, who are more susceptible to infections.
In January 2020, as the pandemic began, investigators began tracking COVID infections among the trial’s 144 participants. They all had type 1 diabetes; Two-thirds had received at least three BCG doses before the pandemic. The remaining one-third had received multiple placebo injections.
Scientists are still evaluating the vaccine’s long-term effects on type 1 diabetes. But they assigned an independent group to look at Covid infections among the participants for 15 months before any of them had received the Covid vaccines.
The results were dramatic: Only one of the 96 people who received the BCG dose – or less than 1 percent – developed COVID, compared to six of the 48 participants who received the dummy shots – or 12.5 percent.
Although the trial was relatively small, “the results are as dramatic as those of the Moderna and Pfizer mRNA vaccines,” said Dr. Dennis Faustman, the study’s lead author and director of immunobiology at Massachusetts General Hospital.
Read more on the coronavirus pandemic
People with type 1 diabetes are especially prone to infections. “We saw a big reduction in bladder infections, fewer flu and fewer colds, lower respiratory tract infections and fewer sinus infections, which are very common in diabetics,” Dr. Faustman said.
The vaccine is “resetting the host’s immune response to be more alert, to be more primary, not lethargic.”
Another trial of BCG in 300 older Greek adults, all of whom had health problems such as heart or lung disease, found that the BCG vaccine reduced COVID-19 infections by two-thirds and the rates of other respiratory infections. reduced.
According to the study, published in July in Frontiers in Immunology, only two individuals who received the vaccine were hospitalized with Covid-19, while six received placebo shots.
“We have seen clear immunological effects of BCG, and it is tempting to ask whether we can use it – or other vaccines that induce training effects on immunity – against a new pathogen that may emerge in the future, which is unknown.” And we do not have a vaccine for it,” said Dr. Mihai Netia, co-lead author of the paper and professor at Radboud University Medical Center in the Netherlands.
He called the results of the type 1 diabetes trial “very strong” but urged caution, noting that other tests have had disappointing results. A Dutch study of nearly 1,500 health care workers who were vaccinated with BCG found no reduction in covid infection, and a South African study of 1,000 health care workers found no effect of BCG on the incidence or severity of covid.
The results of the largest-ever trial of BCG, an international study that followed more than 10,000 health care workers for a year in Australia, the Netherlands, the UK, Spain and Brazil, are still being analyzed and are expected to be out in the next few months. hopefully. The study also followed health care workers when they received the COVID vaccine to see if BCG improved their responses.
“BCG is a controversial area – there are believers and nonbelievers,” said that trial’s principal investigator, Dr Nigel Curtis, professor of pediatric infectious diseases at the University of Melbourne in Australia and leader of the Murdoch Children’s Research Institute’s infectious disease group. , (Dr. Curtis calls himself an “agnostic”.)
“No one argues that there are off-target effects, but how profound is this, and does this translate into clinical effects? And is it limited to newborns, whose immune systems are more sensitive.” ? These are very different questions,” Dr. Curtis said.
Several factors may explain the disparate findings. BCG is made from a live attenuated virus that has been cultivated in laboratories around the world for decades, introducing mutations to different strains.
Dr. Faustman’s lab uses the Tokyo strain, which is known to be particularly potent, Dr. Curtis said. His own study used the Denmark strain, which is the easiest to obtain. The number of doses may also have an effect on immunity, as many vaccines require repeated vaccinations to maximize protection.
Dr. Faustman said his work has shown that it takes time for the vaccine to have maximum effect. The patients with type 1 diabetes received several BCG shots prior to the pandemic in their study.
In any case, scientists interested in BCG’s ability to provide universal, broad-spectrum protection against pathogens have redefined their goals. They are no longer looking to stop Covid-19, because existing vaccines are very effective.
Instead, they want to develop tools for use in the next pandemic, which could be another coronavirus, a deadly new strain of influenza, or an unknown pathogen.
“It’s more for the future,” said Dr Neta, who has called for larger clinical trials of BCG and other vaccines demonstrating broad protective effects.
“If we had known this early in the COVID-19 pandemic, we would have been able to have a major protective effect on the population during the first year of the pandemic.”
The Open Source Pharma Foundation, a global non-profit that seeks to develop affordable new therapies in areas of greatest need, is interested in repurposing off-patent vaccines for use in current and future pandemics. Chairman and Co-Founder Jayakumar Menon said.
“Imagine if we could use existing vaccines to curb the pandemic – that would change world history,” Mr Menon said, adding that BCG is not the only vaccine with widespread effects on the immune system.
“These narrow, very specific vaccines, such as Pfizer or Moderna mRNA vaccines, are placed very tightly on the spike protein of the virus that causes COVID-19, but if that protein is mutated – which it does – you lose efficacy. lose,” said Mr. Menon said.
Alternative? “A broad universal vaccine that works on innate immunity has this strong moat that repels all comers,” he said.
(This story has not been edited by seemayo staff and is published from a rss feed)