Researchers at Baylor College of Medicine in the US have started a clinical trial to assess tuberculosis vaccine, bacille Calmette-Guerin (BCG), for its activity against Covid-19.

In addition to Baylor College, four other institutions have opened enrolment for the BCG vaccine trial.

BCG vaccination mitigates the rate of other infections, according to Baylor College infectious diseases medicine assistant professor Dr Andrew DiNardo.

The BCG vaccine was found to help trigger an immune response against yellow fever and influenza. DiNardo noted that the vaccine may lead to 30% to 50% improvement in immune response against a pathogen such as SARS-CoV-2.

Molecular evidence also shows that BCG alters the body’s responds to a pathogen. It was found to rearrange DNA organisation to facilitate expression of different genes.

The clinical trial will test the vaccine in healthcare workers who treat Covid-19 patients and are at high risk of exposure to the virus. The vaccine will be compared to placebo.

Participants will be tracked using a questionnaire on a smartphone every few days over six months.

Baylor College researchers are working with multidisciplinary teams at Texas A&M University, University of Texas MD Anderson Cancer Center, Cedars-Sinai Medical Center in Los Angeles and Harvard University.

DiNardo said: “It is a very well-known and safe vaccine available now that might be able to work as a buffer until a Covid-19 vaccine is developed, which could take 18 months.

“When a Covid-19 vaccine comes out, the BCG vaccine should be tested with it to see if it improves the efficacy.”

A separate team at Baylor College is conducting a trial to compare two BCG strains for bladder cancer treatment. BCG vaccination is also being tested for its ability to improve the immune response and outcomes in this patient population.