Australian researchers are fast-tracking large-scale human testing to see if a vaccine used for decades to prevent tuberculosis can protect health workers from COVID-19, they announced Friday.

The trial of the BCG vaccine will be conducted with 4,000 health workers in hospitals around Australia to determine if it can reduce COVID-19 symptoms, the researchers at the Murdoch Children's Research Institute in Melbourne said.

"Although originally developed against tuberculosis, and still given to over 130 million babies annually for that purpose, BCG also boosts humans' 'frontline' immunity, training it to respond to germs with greater intensity," they said in a statement.

"We hope to see a reduction in the prevalence and severity of COVID-19 symptoms in healthcare workers receiving the BCG vaccination," said lead researcher Nigel Curtis.

He said the 4,000 subjects would be enrolled in the trial within weeks under a fast-tracked process with the approval of state and federal health authorities. "The clock is definitely ticking," he said.

Similar trials are being conducted in several other countries including the Netherlands, Germany and the United Kingdom.

"This trial will allow the vaccine's effectiveness against COVID-19 symptoms to be properly tested, and may help save the lives of our heroic frontline healthcare workers," said Kathryn North, director of the Murdoch Institute.

She said the hope was that improving people's "innate" immunity against COVID-19 symptoms would buy time to develop a specific vaccine against the disease.

"These trials will allow the rapid advancement of the most promising candidates to clinical practice, giving us the most number of shots on goal against COVID-19 as possible," she said.

© Agence France-Presse