Researchers at the Murdoch Children’s Research Institute have demonstrated that the BCG tuberculosis vaccine can strengthen the immune system for more than a year after administration. The findings appear in a study published in Science Advances, offering new insight into how early vaccination shapes lifelong health in children.
In a randomized controlled trial conducted with 130 infants in Melbourne, one group received the BCG vaccine within ten days of birth while the other did not. At fourteen months, scientists observed significant differences in gene activity within the monocytes of vaccinated children compared with those who were not vaccinated. Monocytes are immune cells that mature into tissue-resident macrophages, which play specialized roles in different organs and bodily tissues. The study notes off-target effects of BCG that were first described in Africa, where vaccinated children showed lower mortality rates. The guiding concept is trained immunity, wherein the vaccine reprograms monocyte genes to heighten the immune system’s responsiveness to a range of infections beyond tuberculosis.
Earlier research on immunostimulation following BCG vaccination primarily involved adults, with observations limited to 1 to 3 months after vaccination. Those findings did not consistently translate to children, who are the main recipients of BCG in many regions. This Melbourne study stands as the first clear demonstration that a dose given in infancy can induce long-term changes in the infant immune system and provides additional confirmation for the trained immunity concept.
The researchers emphasize that the next phase will examine how this early trained immunity may influence health outcomes later in life, including adolescence and adulthood, and whether it affects the risk of future infections or inflammatory conditions. They plan to follow participants further to map long-term immune trajectories and potential clinical consequences, shedding light on lifelong health implications.
Collaborative efforts underpinning the study include partners from Radboud University in the Netherlands, the INTRIM consortium focused on immune education, the University of Melbourne, the Walter and Eliza Hall Institute of Medical Research, and the University of Bonn in Germany. The collaboration highlights growing international interest in how early immune interventions can shape lifelong health and resilience, with potential implications for vaccination policy and child health programs in Canada and the United States. These insights may influence future guidelines on early infant vaccination strategies and the broader aim of strengthening child health systems globally.