Washington: As the world waits for the coronavirus vaccine, scientists, in the meantime, are evaluating two tried-and-true vaccines for Tuberculosis and polio to see if they can offer limited protection against the coronavirus.
Tests are already underway to see if the TB vaccine can slow the novel coronavirus. While other researchers writing in a scientific journal Thursday propose using the polio vaccine, which once was melted on children's tongues, Washington Post reported.
Vaccines developed against TB and polio has already been used in millions of people and could offer a low-risk way to rev up the body's first line of defence -- the innate immune system -- against a broad array of pathogens, including the coronavirus.
The tuberculosis vaccine is also called bacillus Calmette-Guerin and known by the shorthand BCG. The trials for tuberculosis vaccine have begun in the United States, the Netherlands and Australia.
"This is the only vaccine in the world that can be given to combat COVID-19 right now," said Jeffrey D. Cirillo, a professor of microbial pathogenesis and immunology at Texas A&M Health Science Center, who is leading a trial of the tuberculosis vaccine.
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Vaccines are designed to teach the immune system to develop a memory of a particular pathogen but over the years, vaccines that use live, weakened pathogens have been shown to have potent off-target effects.
They can activate other components of the immune response to beat back other infections, including respiratory diseases.
Washington Post reported that the idea is not to prevent COVID-19 altogether but to lessen the severity of the pathogen and prepare the innate immune system to fight against the virus.
The trials started after research comparing rates of coronavirus infections in countries that widely use the tuberculosis vaccine against those that do not initially draw attention to the idea that the inoculation could offer protection.
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If shown effective, those vaccines could potentially protect against the second wave of coronavirus, according to the Post.
A professor of medicine at Columbia University Medical Center said that BCG can improve people's ability to fight off other pathogens.
Azra Raza said that the low death rates from coronavirus disease in Pakistan and other countries shocked her. She pointed out that Pakistan's population is widely vaccinated with BCG.
"It's not like they're not getting the infection," she said. "The rate of positive infections is high. But they're just not dying. It is raging through, but they're not dying of it."
But comparisons among the countries shows that some nations with different BCG use had fewer cases of COVID-19 are far from conclusive.
Many other factors such as differences in testing and health care systems -- and even migration of people between countries with different BCG vaccine policies -- could account for some of the differences.
For example, Brazil has a raging outbreak despite widely using the BCG vaccine.
A study of deaths in Israel depicts a different picture.
"The BCG vaccine was routinely administered to all newborns in Israel as part of the national immunization program between 1955 and 1982," the study said.
"Since 1982, the vaccine has been administered only to immigrants from countries with a high prevalence of tuberculosis."
There is no significant difference between those who received the vaccine and those who did not.
"Facts have a nasty habit of overturning circumstantial evidence," Raza said, adding that the only way to prove it is through future prospective trials.
Michael J. Buchmeier, a professor in the division of infectious diseases at the University of California at Irvine, said there was a risk that such vaccines could have the opposite of the intended effect, making the immune response too strong.
"In its extreme," Buchmeier said, this results in the cytokine storm that can have catastrophic effects on the body.
(ANI)
