BCG Vaccine Shows Potential to Boost SARS-CoV-2 Immunity in Animal Models
Researchers at McGill University explored how the Bacillus Calmette-Guérin (BCG) vaccine interacts with a SARS-CoV-2 vaccine in mice. The findings, shared on bioRxiv, are preliminary until confirmed by peer-reviewed publication.
In the study, the BCG vaccine by itself did not shield the mice from SARS-CoV-2. Comparisons of lung tissue from vaccinated and unvaccinated animals showed no protective difference attributable to BCG alone.
When the intranasal SARS-CoV-2 vaccine was tested, it offered protection to mice, but after six months the viral load in the lungs was similar between those that had been vaccinated and those that had not. Notably, animals that received BCG beforehand exhibited a marked reduction in virus particles compared with their unvaccinated counterparts.
The researchers suggest that BCG may prime the immune system to respond more effectively to the SARS-CoV-2 vaccine, enhancing control of the virus within the respiratory tract.
Additionally, the combination of BCG with the coronavirus vaccine appeared to increase overall effectiveness. The team believes that BCG could pave the way for simpler vaccination schedules in certain situations, without sacrificing protection.
These results add to a broader conversation about how existing vaccines might influence responses to new pathogens. While the data come from animal studies, they contribute to ongoing investigations into vaccine strategies that could support longer-lasting immunity and more flexible immunization approaches. The work is reported with attribution to the investigators and institutions involved, and further validation in humans is needed before any clinical recommendations can be made.