A recently published article in cell reports medicine showed that vaccination against Bacillus Calmette-Guerin (BCG) could provide a platform for protection against emerging variant coronavirus 2 (SARS-CoV-2) severe acute respiratory syndrome and other pathogenic infections in type 1 diabetics.

Study: Multiple BCG vaccinations to prevent COVID-19 and other infectious diseases in type 1 diabetes.  Credit: meeboonstudio/Shutterstock
Study: Multiple BCG vaccinations to prevent COVID-19 and other infectious diseases in type 1 diabetes. Credit: meeboonstudio/Shutterstock


Over the past 17 years, randomized clinical trials and epidemiological investigations have shown that the BCG vaccine against tuberculosis protects people from a wide range of infections such as upper respiratory tract infections, malaria, leprosy, bacterial and viral infections. In addition, the BCG vaccine could protect people from immunological diseases such as multiple sclerosis and type 1 diabetes.

There is a need for effective and safe platform vaccines to immunize against SARS-CoV-2 infections and other contagious pathogens. As the SARS-CoV-2 pandemic began, epidemiological studies began to find an association between neonatal BCG vaccination and lower mortality and morbidity from coronavirus disease 2019 (COVID-19), even in older adults decades after standard vaccinations for newborns in a country. by nation. In contrast, several global groups with different neonatal exposures, BCG strains, and other communities did not show these benefits.

Because adults or neonates in the United States (US) have never received the BCG vaccine, a randomized trial of BCG for potential COVID-19 protection provides a clear comparison in a vaccine-naïve US adult population.

About the study

In the current phase II/III, placebo-controlled, double-blind, randomized research, scientists evaluated the efficacy and safety of the multiple-dose BCG vaccinations for the prevention of COVID-19 and other infectious diseases in a SARS-CoV-2 unvaccinated, high-risk community -based group, over 15 months, from January 1, 2020 to April 2021.

The authors wanted to find out if the BCG vaccine would provide a platform vaccine approach to protect against a variety of infectious diseases such as SARS-CoV-2 infection in the at-risk population.

Adult type 1 diabetics were considered a high-risk group in the study. The team recruited 144 participants and randomly assigned 48 to the placebo and 96 to the BCG arms. In addition, no volunteer dropped out during the 15 months of research.

The present parallel study was derived from an ongoing randomized, double-blind study of BCG for the treatment of long-standing type 1 diabetes in adults. Therefore, at the outbreak of the SARS-CoV-2 pandemic in the USA on January 1, 2020, all participants were fully immunized with three BCG or placebo vaccinations.


The study results showed that in contrast to antigen-specific COVID-19 vaccinations, no participant experienced systemic side effects from BCG during the vaccination period. Localized skin reactions are a known side effect of BCG vaccine and typically begin between two and four weeks after vaccination. No excessive local reactions were documented as side effects. In particular, other SARS-CoV-2 vaccines were not available at the time of the study and did not impact the research.

The BCG vaccine was 92% effective against SARS-CoV-2 infection, with a cumulative incidence of 1% in BCG-treated subjects and 12.5% ​​in placebo-treated volunteers meeting the criteria for confirmed COVID-19 infection. Diagnosis based on symptoms and positive serologies. In addition, the team detected no polymerase chain reaction (PCR)-positive symptomatic subjects in the BCG arm, ie 0%, compared to five symptomatic, PCR-positive participants in the placebo cohort, ie 10.4%.

Looking only at the PCR data, these results showed 100 percent efficacy of the BCG vaccine against SARS-CoV-2 infection at a later probability of 0.99. In addition, there were no SARS-CoV-2-related deaths in either the placebo group or the BCG group.

The researchers found that with the exception of the COVID-19 viral epitope II, virtually all SARS-CoV-2 domains included in the heatmap comparisons showed a noticeably greater accumulation of antibody reactivity in the placebo cohort compared to the BCG -Arm exhibited. In addition, BCG vaccination reduced the duration and severity of all infectious disease symptoms compared to the placebo group.

In addition, the study data showed that all contagious disease symptoms of BCG recipients were similar or less severe than those of their household members. On the other hand, most placebo participants experienced more severe illness compared to their household members. BCG recipients typically experienced milder symptoms than placebo recipients or household controls without diabetes.


In conclusion, the study showed that the BCG vaccine provided effective protection against COVID-19 and comprehensive protection against other infectious diseases in adults with type 1 diabetes in the United States.

The study results also showed that given its comprehensive protection against other infections, the BCG vaccination is efficient, safe, inexpensive and potentially protective against the ever-evolving SARS-CoV-2 strain of the COVID-19 pandemic. The authors mentioned that while the effectiveness of the BCG vaccine may take one to two years to manifest, immunity could last for decades.

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