Coronavirus: could century-old vaccine protect health workers on front line in fight against Covid-19?

Medicine commonly used to guard against tuberculosis is being trialled in Australia

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A tuberculosis vaccine has been given to healthcare workers in Melbourne to find out if it will protect them against coronavirus.

Bacillus Calmette-Guerin, or BCG, has been used widely for about 100 years and there is a growing appreciation for its other health benefits.

Not only is it a common immunotherapy for early-stage bladder cancer, it also seems to train the body to better fight infections.

With a Covid-19 vaccine at least a year away, the World Health Organisation said it was important to know whether BCG could be used to guard against the disease.

The WHO encouraged international groups to collaborate with a study led by Nigel Curtis, head of infectious diseases research at the Murdoch Children's Research Institute in Melbourne.

“It can boost the immune system so that it defends better against a whole range of different infections, a whole range of different viruses and bacteria in a lot more generalised way,” Mr Curtis said.

He is also a professor of paediatric infectious diseases at the University of Melbourne and heads the infectious diseases unit at the city’s Royal Children’s Hospital.

Hospital staff who volunteered to be part of a six-month trial in Australia that involves 4,000 healthcare workers will either be vaccinated against seasonal influenza and TB, or the flu only. Vaccines will be administered at random.

A placebo vaccine will not work as a control in this case because BCG typically causes a localised skin reaction that leaves a scar, making it obvious which group received the TB vaccine.

Similar research is being conducted in the Netherlands.

On Saturday, Mr Curtis said he was in discussion with potential trial sites in other Australian cities, as well as Boston in the US.

Although the inexpensive TV vaccine, which is used to immunise about 130 million newborns worldwide each year, may offer a broader group of people protection against Covid-19, the priority is healthcare workers who are at higher risk from being infected while caring for coronavirus patients.

“We need to think of every possible way that we can protect healthcare workers,” Mr Curtis said.

“And there’s going to be a particular need to reduce the amount of time that our healthcare workers are absent.”

Studies in infants in Africa have shown BCG offers protection against TB and other paediatric infections.

It works by enhancing the body’s innate immune system – specifically white blood cells that target non-specific pathogens before an antibody response has kicked in, usually days later.

Blood samples taken at the start and end of the trial will determine who was infected with coronavirus, while participants will log any symptoms during the trial period.

The study’s data monitoring committee will review the results after three months to look for any signs the approach works.

“We wouldn’t be doing this if we didn’t think that this might work,” Mr Curtis said.

“We cannot guarantee that this will work and, of course, the only way to find out is with our trial.”