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OKLAHOMA CITY (KFOR) – In the race for a coronavirus cure, scientists from Australia are looking at a 100-year-old tuberculosis vaccine as a possible weapon against COVID-19.

For decades, BCG was used to treat tuberculosis, which is caused by a type of bacteria.

Some scientists believe it may boost immunity for other respiratory illnesses, but Dr. Linda Thompson, with the Oklahoma Medical Research Foundation, is skeptical.

“The effects of it diminish pretty quickly over time, so I could see if someone had recently been vaccinated with BCG and then encountered some other virus, they might have an enhanced immune response to it,” Thompson said.

The interest in BCG was sparked after countries where the vaccine is commonly used, such as Japan, had lower rates of COVID-19.

“But then if you go down to Spain, what stopped it in 1981, that means old people had the BCG vaccination and they have the highest rate of all,” Thompson said.

Dr. Thompson also warns the vaccine may actually be dangerous for the elderly and immune compromised individuals.

“Most people who are dying from it are dying because the immune system is too activated,” Thompson said.

“So if you gave someone BCG while they were actively infected with coronavirus, it could really be a disaster,” Thompson added.

She worries there may never be a vaccine for COVID-19, which is also the case for SARS and MERS.

“Sometimes when people are exposed to them, they make antibodies that actually increase the ability for the virus to enter human cells and that’s what was true for the SARS virus and that’s why there’s no SARS vaccine yet,” Thompson said.

The World Health Organization says two clinical trials are underway but say there is no evidence BCG will protect people against COVID-19.

It says it will evaluate the findings when they’re available.

Meanwhile, Dr. Thompson says a drug called remdesivir shows a lot of promise in treating the novel coronavirus.