BCG has been the most extensively administered vaccine in medical history since its debut in 1921.
The BCG vaccination is an avirulent TB strain Mycobacterium bovis that was previously used to protect against tuberculosis. BCG is on the World Health Organization’s List of Essential Medicines and is administered to around 100 million children worldwide each year. BCG is also one of the cheapest treatments, with many countries charging less than $1 for each dosage. Multiple doses of the Bacillus Calmette-Guerin (BCG) vaccine protect against COVID-19 and other infectious disorders, according to researchers at Massachusetts General Hospital (MGH).
Researchers discovered that 12.5% of placebo-treated individuals and 1% of BCG-treated individuals met the criteria for confirmed COVID-19 in a double-blind, placebo-controlled study of patients with type 1 diabetes conducted at the start of the pandemic (before COVID-specific vaccines were available), yielding vaccine effectiveness of 92%. The BCG-vaccinated group also showed protective benefits against various infectious illnesses, such as fewer symptoms, less severe disease, and fewer contagious disease episodes per patient. There were no systemic adverse effects due to BCG.
The broad-based infection protection provided by BCG implies that, in addition to COVID-19, it may give protection against future SARS-CoV-2 variants and other infections. The researchers hope that the findings will inspire a more extensive investigation of the effects of the BCG vaccination in type 1 diabetic patients, who are thought to be among the most vulnerable populations to COVID-19.
“Multiple studies have demonstrated that persons with type 1 diabetes who are identified with COVID-19 are at higher risk of serious disease. We discovered that three doses of BCG given before the outbreak of COVID-19 and other infectious disorders avoided infection and reduced severe symptoms. “Unlike the antigen-specific vaccinations now being used to prevent COVID-19, the mechanism of action of BCG is not restricted to a single virus or infection,” explains Denise Faustman, MD, Ph.D., head of the Immunobiology Laboratory at Massachusetts General Hospital.
The COVID study participants had previously participated in a clinical trial assessing the efficacy of the BCG vaccination for type 1 diabetes. Prior to the pandemic’s commencement in early 2020, participants in the test group had gotten numerous immunizations.
“This data set is unusual and fascinating since the patients were all immunized with many doses of BCG before the outbreak. They had no past TB exposure or BCG immunization prior to the experiment. This removes the primary confounding issues that have hampered previous experiments. “The findings reinforce the concept that BCG takes time to have a clinical effect, but once it does, the benefits may be quite long-lasting and permanent,” says Hazel Dockrell, an infectious diseases expert who was not formally involved in the study.
The COVID-19 experiment had the following results: a COVID-19 infection rate, COVID-19-associated symptoms, a decrease in overall infectious illness, and SARS-CoV-2 antibody levels, presence, and intensity. The type 1 diabetes results were not blinded as part of this investigation but will be when the trial concludes in 2023.
The 144 adult type diabetics studied in the COVID-19 experiment (96 BGC treated and 48 placeboes) were part of an ongoing Phase IIb clinical trial investigating BCG as a therapy for individuals with established type 1 diabetes. For 15 months, patients were monitored for COVID-19-related outcomes.
Parvathy Sukumaran 
