Known for more than a century, would the BCG vaccine be effective against Covid-19 in patients less well protected by the mRNA vaccine? This is what American researchers suggest according to which Repeated BCG injections could help reduce the risk of Covid-19 in type 1 diabetic patients. Focus on the conclusions of their work.
What is the BCG vaccine?
Developed more than a century ago, BCG vaccine refers to a live attenuated vaccine, that is to say composed of live but weakened tuberculosis bacilli. Administered intradermally, this vaccine strongly limits the risk of developing tuberculosis infection and helps prevent serious forms in children. With an effectiveness ranging from 75 to 85%, this vaccine must be administered to infants during the second month of life or from birth if a case is detected in those around them.
To know ! Certain cases contraindicate vaccination, such as extensive skin disease, immunosuppression, HIV seropositivity or treatments based on corticosteroids or immunosuppressants (chemotherapy).
In the early days of the Covid-19 pandemic, a line of research was raised according to which the BCG vaccine could be effective against SARS-Cov-2 in the general population. But the controversial results of studies carried out on an international scale as well as the development of the mRNA vaccine have overturned this hypothesis.
Four years later, American researchers from Massachusetts General Hospital are relaunching the debate by focusing on the effectiveness of the BCG vaccine against Covid-19 in patients at risk and with type 1 diabetes.
BCG vaccine and effective anti-infectious protection in type 1 diabetic patients
Scientists were particularly interested in type 1 diabetic patients after observing the lack of significant protection against SARS-CoV-2 conferred by mRNA vaccines in this particular population.
To carry out their research, American scientists therefore developed two phase 2 and 3 clinical trials including 141 patients from the cohort BCG Trial implemented before the Covid-19 pandemic. None of these patients had received BCG vaccine in childhood. Among the 141 participants:
- 93 were randomized to the “BCG group” with multiple intradermal injections: five doses (30%) or six doses (70%) of the Tokyo strain of BCG.
- 48 were randomized to the “placebo group” with dummy injections.
Regarding the injection protocol, the participants received:
- 3 injections, during the 26 months preceding the Covid-19 pandemic.
- 2 injections during the first wave of Covid-19.
- A final injection during the second phase of the pandemic (with circulation of the Beta, Gamma, Delta and Omicron variants).
After analyzing the data, the scientists were able to observe the following results:
- BCG vaccine 92% effective against Covid-19 in phase 2 trial and efficacy of 43.2% in the phase 3 trial.
- Effectiveness of 54.3% over the 34 months studied.
- No interference between BCG vaccination and the effectiveness of Covid vaccines.
- Fewer infections of all types in participants of the BCG group.
Published in the journal iSciencethese results show that multiple injections of the BCG vaccine would significantly protect type 1 diabetic patients from infection by Covid-19 but also from other infections whether viral, bacterial or fungal.
Long-lasting protection against infectious diseases
For the authors of this study, the BCG vaccine is interesting in that it could protect patients for decades against any variant of Covid-19, influenza, respiratory syncytial virus and other infectious diseases.
Next step for American researchers? Have BCG vaccination authorized in their country in type 1 diabetic patients, particularly at risk for all infectious diseases. They also aim to check whether the BCG vaccine can better protect them against severe forms of Covid-19. To be continued!
Déborah L., Doctor in Pharmacy
Sources
– The BCG trail against Covid relaunched in type 1 diabetic patients. www.lequotidiendumedecin.fr. Accessed May 30, 2024.
– Late in the US pandemic, multi-dose BCG vaccines protect against COVID-19 and infectious diseases. www.cell.com. Accessed May 30, 2024.
