Study examines healthcare workers’ susceptibility to COVID-19 variants

By Melissa Coade

Thursday June 10, 2021

tuberculosis vaccine
We’ll see if the tuberculosis vaccine will work on a new COVID-19 variant. (Image: Adobe/Alexey Novikov)

A new trial examining positive effects of tuberculosis vaccine on COVID-19 immune response among healthcare workers will now also consider people’s susceptibility to getting sick from the virus when exposed to a new variant.

The Australian-led study will look at the susceptibility to SARS-CoV-2 variants that people who have either recovered from COVID-19 or received a vaccine may have.

The researchers will analyse the immune response of Brazilian healthcare workers who have received a COVID-19 specific vaccine. The call has also been made for healthcare volunteers (already participating in BRACE) in Victoria and South Australia to join the trial. 

The research is a sub-study of the Murdoch Children’s Research Institute’s (MCRI) BRACE randomised controlled clinical trail – the world’s largest study assessing if the Bacille Calmette-Guérin (BCG) vaccine (which was developed 100 years ago to prevent tuberculosis) can help protect against COVID-19.

The trial will specifically examine whether the BCG vaccine ‘reduces the incidence of symptomatic and severe COVID-19 in healthcare workers’ or reduce the impact of other respiratory illnesses and allergic diseases. 

The sub-study trial, known as BCOS, will also look at whether immune responses to Pfizer, AstraZeneca and CoronaVac vaccines are improved in addition to receiving the BCG vaccine

More than 6,800 healthcare workers across 36 settings in Australia, Brazil, the Netherlands, Spain and the UK have enrolled to participate in the BRACE trial since it commenced in March 2020. 

For BCOS, a total of 2,400 healthcare workers across three trial sites in Brazil are being actively monitored and tested for COVID-19. Scientists will examine biomarkers of the trial participants to see if there is any indication whether someone remains at risk of contracting the virus if exposed to a COVID-19 variant.

According to BRACE trial principal investigator Associate Professor Julio Croda, the sub-study trial is a unique way to understand the ‘risks and determinants of susceptibility to reinfection with SARS-CoV-2 variants and the P.1 variant especially.

“This research is critical to designing effective approaches to help protect people,” Croda said.

MCRI head of infectious diseases research group Professor Nigel Curtis said the potential impact of SARS-CoV-2 variants is a serious issue facing the world in 2021, with new variants emerging – for which vaccine-induced and natural immune responses may not be as effective.

“There is concern that herd immunity may be undermined. If this happens, SARS-CoV-2 will continue to spread and cause disease,” Curtis said.

The BCOS researchers are now recruiting other BRACE trial participants to see whether they experience any ‘better or prolonged immune response’ when receiving the BCG vaccine together with another COVID-19 specific vaccine.

MCRI Director Professor Kathryn North added that the participants would be followed-up every three months with questionnaires and blood collection and phone-calls. Trial participants would also undertake self-reporting via a smartphone app.

“A deeper understanding of immune responses to COVID-19-specific vaccines will be important to the global effort to contain this pandemic,” North said. 

The study has received philanthropic funding from the Bill & Melinda Gates Foundation, Sarah and Lachlan Murdoch, Minderoo Foundation, The Royal Children’s Hospital Foundation, South Australian government, NAB Foundation, The Calvert Jones Foundation, UHG Foundation, Modara Pines Charitable Foundation, Health Services Union NSW, Peter Sowerby Foundation, South Australia Ministry of Health, Epworth Health, Swiss National Science Foundation and individual donors.


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