IN NOVEL RESULTS published from a double-blind, placebo-controlled study of patients with Type 1 diabetes, researchers demonstrated a protective effect of Bacillus Calmette–Guerin (BCG) vaccine. The BCG vaccine is an anti-virulent tuberculosis strain which has historically been given to protect against tuberculosis. The vaccine is considered extremely safe, very affordable at less than a dollar a dose in most of the world, and is the most widely administered vaccine in the history of medicine.
The trial, conducted at the beginning of the COVID-19 pandemic, found that 12.5% of placebo-treated individuals compared to just 1.0% of BCG-treated individuals met the criteria for confirmed COVID-19 infection. The BCG-treated individuals further exhibited protection against other infectious diseases, with few less severe symptoms, and a lower number of infectious disease-related events.
Multiple studies throughout the pandemic demonstrated that individuals with Type 1 diabetes are at increased risk of severe illness when infected with COVID-19. The participants in the trial had been enrolled to test the efficacy of BCG vaccine for Type 2 diabetes.
“We found that three doses of BCG administered prior to the start of the pandemic prevented infection and limited severe symptoms form COVID-19 and other infectious diseases,” stated Denise Faustman, Director of Immunobiology Laboratory, Massachusetts General Hospital, Boston, USA. “This data set is unique and exciting because the patients were all vaccinated with multiple doses of BCG prior to the onset of the epidemic. Prior to the trial they had no known exposure to tuberculosis or prior BCG vaccination.”
Unlike the antigen-specific COVID-19 vaccines which are currently used to prevent COVID-19, the mechanism of action of BCG is not specific to a particular virus or infection. Furthermore, the results support the idea that BCG vaccination takes time to have clinical effect, but that its impact may well be lasting and durable.