Researchers in the United Kingdom said on Sunday they were testing whether a widely-used tuberculosis vaccine can protect front-line health care workers from COVID-19.
Professor John Campell is the study's lead researcher at the University of Exeter Medical School.
"It's an incredibly safe vaccine. We know that that's the case. It's still given to 120 million babies, each year."
Bacillus Calmette-Guérin vaccine, or BCG, helped eradicate TB in the UK. But it also has been shown to stimulate an immune response that can protect against other illnesses as well.
"And that's been demonstrated in previous experimental work. And that's really important because these are called the 'off-target' effects. They're not against TB, but it's using the vaccine as a sort of booster to the immune system more generally."
The UK study is part of an existing Australian-led trial, which launched in April, and also has arms in the Netherlands, Spain and Brazil.
The BCG vaccine is also being tested against COVID-19 in South Africa.
In the United Kingdom, researchers are hoping to enroll 1,000 people who work in health care.
Dr. Sam Hill has a general practice, and volunteered.
"Personally, I don't want to get really ill this winter, but also with a business to run, and patients to look after, if I can get better from COVID quickly and get back to work, then that's a real benefit for me."
Professor Campbell said he didn't expect the BCG trial to result in a miracle cure, but said anything that grants even a bit of protection from the pandemic was a tool in healthcare workers' kit.
"It may be that the BCG could buy us very, very valuable time and protect healthcare and protect global economies and protect individuals and families who are at risk."