A recent study by Massachusetts General Hospital (MGH) researchers showed the effectiveness of repeated doses of the Bacillus Calmette-Guerin (BCG) vaccine in protecting against COVID-19 and other infectious diseases.
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), the researchers found that 12.5% of placebo-treated individuals and 1% of BCG-treated individuals met the criteria for confirmed COVID-19, yielding vaccine effectiveness of 92%.
The BCG-vaccinated group also displayed protective effects against other infectious diseases, including fewer symptoms, lesser severity and fewer infectious disease events per patient.
No BCG-related systemic adverse events occurred.
BCG’s broad-based infection protection suggests that, in addition to COVID-19, may potentially provide protection against new SARS-CoV-2 variants and other pathogens.
As one of the populations thought to be most susceptible to COVID-19, type 1 diabetes patients, the researchers are hopeful the findings will motivate a larger-scale investigation of the effects of the BCG vaccine in this population.
Since its debut in 1921, the BCG vaccination—which uses an avirulent tuberculosis strain of Mycobacterium Bovis to protect against tuberculosis—has been the most commonly used vaccine in medical history.
BCG is administered to over 100 million children a worldwide year and is thought to be quite safe. It is included on the World Health Organization’s list of essential medicines. BCG is also one of the least expensive medications, with many regions of the world charging less than $1 per dose.
“Multiple studies have shown that adults with type 1 diabetes who are diagnosed with COVID-19 are at increased risk of severe illness.
We found that three doses of BCG administered prior to the start of the pandemic prevented infection and limited severe symptoms from COVID-19 and other infectious diseases.
Unike the antigen-specific vaccines currently in use to prevent COVID-19, BCG’s mechanism of action is not limited to a specific virus or infection,” says Denise Faustman, MD, PhD, director of the Immunobiology Laboratory at Massachusetts General Hospital.
“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.
This eliminates the major confounding factors that have limited other trials.
“The results support the idea that BCG needs time to have a clinical effect, but its effects may then be very lasting and durable” says Hazel Dockrell, London School of Hygiene & Tropical Medicine, an infectious diseases expert who was not officially involved in the study.
The 144 adult type diabetics (96 BGC treated and 48 placebo) analyzed in the COVID-19 trial were part of an ongoing Phase IIb clinical trial testing BCG as a treatment for adults with established type 1 diabetes.
Patients were followed for COVID-19-related outcomes for 15 months.
Outcomes for the COVID-19 trial included: COVID-19 infection rate, COVID-19 related symptoms, reduction overall infections disease and SARS-CoV-2 antibody-level presence and intensity.
The type 1 diabetes outcomes were not unblinded as part of this study and will be unblinded at the completion of the trial in 2023.
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Source: Technology Networks