Researchers at Texas A&M University in the US are asking hundreds of frontline medical workers to participate in a Phase 4 clinical trial of a widely used tuberculosis vaccine that could blunt the devastating effects of COVID-19.

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The researchers hope to demonstrate that the Bacillus Calmette-Guerin (BCG) vaccine mitigates the effects of the virus, allowing fewer people to be hospitalised or to die from COVID-19.

Texas A&M is the first US institution in the clinical trial to have federal clearance for testing on humans. Healthcare workers will be the first people eligible for clinical trials. Recruitment of 1,800 volunteers to participate in the trial is already underway, the university said in a statement. "It's not going to prevent people from getting infected," said Jeffrey Cirillo, Professor at the Texas A&M Health Science Center.

"This vaccine has the very broad ability to strengthen your immune response. We call it ‘trained immunity.' "This could make a huge difference in the next two to three years while the development of a specific vaccine is developed for COVID-19."

The Texas A&M Chancellor recently offered $2.5 million to make sure the work of Dr. Cirillo can move forward as quickly as possible. "If there was ever a time to invest in medical research, it is now," the Chancellor said.

BCG is used to treat bladder cancer in the US. Cirillo said repurposing the existing bladder cancer vaccine, called TICE BCG, could result in bringing a COVID-19 treatment to the public in the fastest possible way. Because the drug is already approved by the FDA, Cirillo can skip the first three phases of clinical trials usually required before testing on people, since this vaccine has already passed those phases. The vaccine could be widely available for use against COVID-19 in just six months because it has already been proven safe for other uses, according to the researchers.