Human trials for a tuberculosis vaccine thought to boost immune systems in the fight against coronavirus are underway in Australia but despite the promising outlook, the World Health Organisation (WHO) has warned against using the vaccine outside of clinical settings.
WHO has released a statement reminding countries around the world that the Bacille Calmette-Guérin vaccine (BCG) used to fight tuberculosis infection is not recommended for preventing coronavirus.
It acknowledged that while experimental trials had been conducted and two related to fighting coronavirus were underway, their relevance to the pandemic was still unknown.
“Two clinical trials addressing this question are underway, and WHO will evaluate the evidence when it is available,” a WHO scientific briefing outlined on April 12.
“In the absence of evidence, WHO does not recommend BCG vaccination for the prevention of COVID-19. WHO continues to recommend neonatal BCG vaccination in countries or settings with a high incidence of tuberculosis.”
One such trial, the BRACE trial, is happening in Australia and is being led by the Murdoch Children’s Research Institute. Human trials, which started on March 30, are being conducted among 4,000 healthcare workers across the country with 1,500 workers already being recruited.
The trial’s lead researcher, Professor Nigel Curtis, told Gizmodo Australia it agreed with the WHO’s statement urging countries not to use the vaccine outside of clinical trials.
“We strongly agree with the WHO that BCG in relation to protecting against COVID-19 should only be used in randomised clinical trials,” Professor Curtis said in an email.
Back in March, Professor Curtis told reporters in a research briefing he had been approached by the WHO to see whether the vaccine, which had shown promising results against other diseases, might be useful in this situation.
“More than a month ago when COVID-19 was first detected in China, I was contacted by the WHO [World Health Organisation] who asked whether we thought the beneficial off-target effects of BCG might be helpful to protect frontline healthcare workers in China,” Professor Curtis said.
“Healthcare workers are at high risk and are very vulnerable. There have already been deaths of healthcare workers [globally]… and so we felt this was an ideal group of individuals to try and protect using the BCG vaccine.”
While the BCG vaccine isn’t designed as a cure for coronavirus, the hope is that it can boost the immune systems of healthcare workers treating coronavirus patients on the frontline. Professor Curtis told Gizmodo Australia that seven sites for the trial had been confirmed so far — Melbourne’s Royal Children’s Hospital, South Australia’s Royal Adelaide Hospital, Flinders Medical Centre and the Women’s and Children’s Hospital as well as Perth Children’s Hospital, Fiona Stanley Hospital, and Sir Charles Gairdner Hospital in Western Australia.
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WHO’s statement pointed to a review that found a potential correlation regarding the amount of cases between countries that had high usage of the vaccine and those that didn’t but said there could be a number of other contributing factors affecting this finding.
“The review yielded three preprints (manuscripts posted online before peer-review), in which the authors compared the incidence of COVID-19 cases in countries where the BCG vaccine is used with countries where it is not used and observed that countries that routinely used the vaccine in neonates had less reported cases of COVID-19 to date,” WHO’s scientific brief read.
“Such ecological studies are prone to significant bias from many confounders, including differences in national demographics and disease burden, testing rates for COVID-19 virus infections, and the stage of the pandemic in each country.”
In Australia, tuberculosis vaccines haven’t been administered to children in decades due to the drop in prevalence of the deadly bacterial disease. Professor Curtis said only children under five who were travelling to countries where tuberculosis is prevalent could get the vaccine so there was no risk of people rushing out and scoring their own for self-inoculation.
For now, Australia’s trial of the BCG’s effectiveness remains underway with interim results expected by June or July before the full trial is completed at the six-month mark.
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