Why a Century-Old Vaccine Offers New Hope Against Pathogens

In the early days of the Covid-19 pandemic, prevention seemed light years away, but researchers wondered whether a tuberculosis vaccine developed in the early 1900s could protect people by boosting their immune systems. To confirm, several scientists started testing.

The Bacillus-Calmette-Guerin vaccine has long been known to have wide-ranging effects on the immune system and is still administered to infants in developing and tuberculosis-endemic countries.

Scientists observed many years ago that vaccines train the immune system to respond to various infections such as viruses, bacteria and parasites and appear to reduce infant mortality. rice field.

As new threats such as monkeypox and polio reemerge and coronaviruses continue to evolve, the potential for old vaccines to provide universal protection against infectious diseases has sparked renewed interest among scientists. I’m here.

Results from clinical trials conducted during the pandemic are now available, and although the results are mixed, they are promising.

The latest results, published Monday in Cell Medicine Reports, come from trials that began before the emergence of Covid-19.It was Designed to see if multiple BCG injections have been given It may help people with type 1 diabetes who are prone to infection.

In January 2020, when the pandemic began, investigators began tracking Covid infections in 144 trial participants. All were her type 1 diabetes. Two-thirds said he had at least three doses of her BCG before the pandemic. The remaining one-third of her had multiple placebo injections.

Scientists are still evaluating the long-term effects of the vaccine on type 1 diabetes itself. investigated for Covid infection.

The results were dramatic. Only 1 of his 96 (less than 1%) who received BCG developed her Covid, whereas 6 of her 48 (12.5%) who received a dummy shot developed her I got Covid.

Although the trial was relatively small, “the results are as dramatic as those of Moderna’s and Pfizer’s mRNA vaccines,” said lead author of the trial and chief of immunobiology at Massachusetts General Hospital. Dennis Faustmann, Ph.D.

People with type 1 diabetes are particularly susceptible to infections. “There was a significant reduction in bladder infections and a reduction in flu, colds, respiratory tract infections, and sinus infections that are common in diabetics,” added Dr. Faustmann.

The vaccine “seems to reset the host’s immune response to make it more agile and more prepared, rather than sluggish.”

Another trial of BCG in 300 older Greeks with health problems such as heart disease and lung disease found that BCG vaccine reduced Covid-19 infections The incidence of other respiratory infections was also reduced by two-thirds.

A study published in July in Frontiers in Immunology found that only two people who received the vaccine were hospitalized with Covid-19, compared to six who received placebo injections.

“We have seen clear immunological effects of BCG. We are tempted to ask if BCG can be used, or if other vaccines that induce a training effect on immunity can be used.” Lead author Dr. Mihai Netea, professor at Radboud University Medical Center in the Netherlands, said:

He called the type 1 diabetes trial results “very strong,” but cautioned that other trials had disappointing results. Dutch study of about 1,500 health workers People vaccinated with BCG showed no reduction in Covid infections, a South African study 1,000 healthcare workers No effect of BCG on Covid incidence or severity was found.

As a result of BCG’s largest trial, International study tracking over 10,000 healthcare workers Australia, the Netherlands, the UK, Spain and Brazil are still under analysis for a year and will be projected in the coming months. The study followed health care workers after receiving the Covid vaccine to see if BCG improved their response.

“BCG is a controversial field. There are believers and non-believers,” said the principal investigator of the trial, a professor of pediatric infectious diseases at the University of Melbourne in Australia and an infectious disease researcher at the Murdoch Institute for Pediatrics. Group leader Nigel Curtis, Ph.D. (Dr. Curtis calls himself an “agnostic.”)

“No one claims there are off-target effects, but how severe are they and do they lead to clinical effects? And are they limited to newborns, whose immune systems are more susceptible?” See? Those are very different questions,” Dr. Curtis said.

There are many factors that could explain the different findings. BCG consists of live, attenuated viruses that have been cultured for decades in laboratories around the world, introducing mutations that create different strains.

Dr. Curtis said Dr. Faustmann’s lab uses the Tokyo strain, which is believed to be particularly potent. In his own research, he used the easiest Danish strain he had available. The number of doses given can also affect immunity, as many vaccines require repeated doses to maximize protection.

Dr. Faustmann said her research shows that vaccines take time to reach their full potential. Her type 1 diabetic who participated in her study had received several of her BCG injections before the pandemic.

In any case, scientists interested in the potential of BCG to provide universal, broad-spectrum protection against pathogens changed its purpose. Current vaccines are so effective that they no longer look to prevent Covid-19.

Instead, they want to develop tools for use in the next pandemic. It could be another coronavirus, a deadly swine flu, or an unknown pathogen.

Dr. Netea has called for large-scale clinical trials of BCG and other vaccines, which have demonstrated broad protective efficacy, he said.

“Had we known this at the beginning of the Covid-19 pandemic, we could have had a significant protective effect on the population in the first year of the pandemic.”

Open Source Pharma Foundation, a global nonprofit seeking to develop affordable new treatments in areas of greatest need, will repurpose off-patent vaccines for use in current and future pandemics is interested in doing so, said its chairman and co-founder Jaykumar Menon.

“If we could use an existing vaccine to curb a pandemic, it would change the history of the world,” Menon said, adding that BCG is not the only vaccine with a broad impact on the immune system.

“Like Pfizer’s and Moderna’s mRNA vaccines, these limited, highly specific vaccines reach the spike protein of the virus that causes Covid-19 very tightly, but when that protein mutates,[When it mutates]it loses potency,” he said. Menon said.

What are the alternatives? “Broad universal vaccines that act on innate immunity will build this fortified moat that repels all invaders,” he said.

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