Could old vaccines for tuberculosis and polio help fight COVID-19?

Researchers are hopeful that vaccines used to combat tuberculosis and polio could be used to treat COVID-19. 

The Washington Post reports that tests are already underway to see if the tuberculosis vaccine, which was developed in the early 20th century, can slow COVID-19. Other researchers propose using the polio vaccine, which was developed in the 1950s. 

These vaccines would not replace the actual COVID-19 vaccines currently being developed around the world. Instead, they could be used to strengthen immune systems and reduce the severity of symptoms. The Post reports that “vaccines that use live, weakened pathogens have been shown to have potent off-target effects, activating other components of the immune response to beat back other infections, including respiratory diseases.” 

Jeffrey D. Cirillo, a professor of microbial pathogenesis and immunology at Texas A&M Health Science Center, told the newspaper that the TB vaccine called BCG is “the only vaccine in the world that can be given to combat COVID-19 right now.” 

Azra Raza, a professor of medicine at Columbia University Medical Center, said the wide use of the BCG vaccine in Pakistan might be why the country has a low death rate from COVID-19.

“It’s not like they’re not getting the infection,” Raza told the Post. “The rate [of positive infections] is high. But they’re just not dying. It is raging through, but they’re not dying of it.”

However, the phenomenon in Pakistan hasn’t always been replicated in other countries where the BCG vaccine is still given to the public. For example, Brazil still has a severe COVID-19 outbreak despite widespread use of the BCG vaccine. 

Dr. Robert Gallo, the director of the Institute of Human Virology at the University of Maryland School of Medicine, advocates in the journal Science for the review of how the polio vaccine could combat COVID-19. He and his colleagues want funding and approval to start clinical trials.

Their hypothesis refers to a three-year controlled trial in Russia in the 1960s that found that “giving adults doses of the oral poliovirus vaccine cut deaths due to seasonal influenza and acute respiratory diseases three-fold,” according to NBC News

Not all researchers agree that either vaccine would be useful in combating COVID-19, but no one will know for sure unless scientists conduct clinical trials. 

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Sources: Washington Post, NBC News, Science

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