Australian scientists think the key to stopping the COVID-19 pandemic could lie in a century-old tuberculosis vaccine.
Since 1921, the Bacillus Calmette–Guérin (BCG) vaccine has been used to prevent tuberculosis, which is caused by a bacteria - not a virus.
But researchers at the University of Sydney think it can be adapted to fight off SARS-CoV-2, the virus which has infected more than 10 million people and killed more than half-a-million since emerging in China late last year.
Their invention - the BCG:CoVac vaccine - combines the BCG vaccine with proteins from the surface of the SARS-CoV-2 virus, teaching the immune system what they look like so it can respond if the real thing ever shows up.
"These initial results are very promising," said Jamie Triccas of the university's School of Medical Sciences.
"BCG:CoVac is making the type of immune response that we predict is needed to control SARS-CoV-2 infection in humans. We are currently determining how well the antibodies generated after vaccination can 'block' the virus from infecting cells and thus provide protection from disease."
The BCG vaccine is given to around 100 million children every year. It's available in New Zealand too for kids deemed at high risk of the disease, which kills around 1.5 million people every year, mostly in Africa and south Asia.
There's currently high demand for the vaccine, according to the Auckland Regional Public Health Service, perhaps because it's also effective at preventing other infections - perhaps even COVID-19, though the data is unclear on that.
In addition to using proteins specific to the coronavirus, BCG:CoVac doesn't appear to trigger inflammatory responses, which often hold up other vaccine candidates.
The Australian scientists are currently testing how long their combination vaccine provides protection in mice, before human trials.
"Our on-going studies will determine how long the immune response lasts after vaccination in animal models. This is important information for future human testing of our vaccine," said Dr Claudio Counoupas, research scientist at the Centenary Institute and research co-leader.