The widely used BCG tuberculosis vaccine will be tested on frontline care workers in Britain for its effectiveness against COVID-19, researchers running the UK arm of a global trial said.
Bacillus Calmette-Guérin (BCG) vaccine, used to protect against tuberculosis, induces a broad innate immune-system response and has been shown to protect against infection or severe illness with other respiratory pathogens.
"BCG has been shown to boost immunity in a generalised way, which may offer some protection against COVID-19," Professor John Campbell, of the University of Exeter Medical School, said.
"We are seeking to establish whether the BCG vaccine could help protect people who are at risk of COVID-19. If it does, we could save lives by administering or topping up this readily available and cost-effective vaccination."
The UK study is part of an existing Australian-led trial, which launched in April and also has arms in the Netherlands, Spain and Brazil. The BCG vaccine is also being tested as a protection against COVID-19 in South Africa.
The British trial is recruiting volunteers ahead of winter months that officials have warned may be tough as the country grapples with a second wave of infections.
UK Prime Minister Boris Johnson has indicated that restrictions to curb the pandemic could be in place until spring.
The trial's UK arm, which is being run from Exeter, southwest England, is seeking to recruit 1,000 people who work in care homes and community healthcare nearby.
Globally, more than 10,000 healthcare staff will be recruited.