When babies in the African countries of Guinea Bissau and Uganda were given the tuberculosis vaccine, something remarkable happened.
Instead of the vaccine only protecting against the target bacteria – Myocbacterium tuberculosis – the tuberculosis vaccine offered broad protection against a range of unrelated infections, including respiratory infections and serious complications such as sepsis.
The team administered the Bacille Calmette-Guérin (BCG) vaccine to 63 infants within ten days of their birth and compared their progress to a control group of 67 infants who did not receive the BCG vaccine.
The researchers took blood samples from the infants and examined circulating white blood cells called monocytes in both groups.
Monocytes are part of the human body’s innate immune system, which provides the first line of defense against pathogens and is not specific to any one disease.
Looking at these monocytes, researchers found distinct epigenetic differences – changes to the way genes are expressed or control which genes are active and which are switched off – between the vaccinated group and the unvaccinated group that lasted on average around 14 months after vaccination.
In vaccinated babies, the BCG vaccine reprogrammed or ‘trained’ monocytes to be more responsive to pathogens in general, and this epigenetic signature was passed down to the next generation of monocytes for more than a year after vaccination.
“For the first time, we have shown how the BCG vaccine can have long-lasting effects on the immune system of infants,” says Boris Novakovic, senior author and molecular biologist at the Murdoch Children’s Research Institute (MCRI) in Melbourne, Australia.
The researchers also used an in vitro experiment to explore these epigenetic changes in detail.
They isolated monocytes from healthy adults and exposed the cells to two types of the BCG vaccine and detected distinct changes in different types of epigenetic modifications.
These included DNA methylation – molecular tags adoring the DNA sequence – and histones – bulky proteins around which DNA strands are wound.
Monocytes respond to pathogens using receptors on the cell’s outside surface.
When these receptors contact a pathogen, it triggers the monocyte cell to ‘eat’ the pathogen (phagocytosis), which also causes a cascade of events inside the cell where one protein switches on another protein and so on, until this triggers a change in the gene expression of the cell.
Putting monocytes on high alert makes them more responsive to all infections, not just tuberculosis.
It was previously thought that the innate immune system had no way of remembering previous infections, unlike the adaptive immune system (which uses T cells and specific antibodies to remember the pathogens it has encountered before).
Over the last decade, scientists have discovered that the innate immune system can actually produce a non-specific memory, called ‘trained immunity’.
“That’s been the breakthrough,” Novakovic told ScienceAlert.
It’s not just the BCG vaccine that makes the innate immune system hyperresponsive. Other live attenuated vaccines that use a weakened form of the virus to protect against diseases such as polio, measles, and smallpox have a similar effect.
Conditions that put stress on the body, such as obesity and high cholesterol, or injuries, also make the innate immune system more responsive. That’s not always a good thing.
In countries where infant mortality is high, vaccinating against tuberculosis, measles, or smallpox may have a beneficial effect in protecting infants against a range of other infections.
In an Australian context where babies rarely die of infectious diseases, there is greater interest in the potential use of the BCG vaccine to prevent allergies and eczema in kids, Novakovic said.
The thinking is that the BCG vaccine may have a beneficial effect on the developing immune system.
A study from MCRI researchers published in Allergy last year found that BCG vaccination had a modest beneficial effect in preventing eczema in infants predisposed to developing the common skin condition.
The epigenetics study was published in Science Advances
News
AI therapy may help with mental health, but innovation should never outpace ethics
Mental health services around the world are stretched thinner than ever. Long wait times, barriers to accessing care and rising rates of depression and anxiety have made it harder for people to get timely help. As a result, governments and health care providers are [...]
Global life expectancy plunges as WHO warns of deepening health crisis Post-COVID
The World Health Organization (WHO) has sounded the alarm on the long-term health repercussions of the COVID-19 pandemic in its newly released World Health Statistics Report 2025. The report reveals a staggering decline in global [...]
Researchers map brain networks involved in word retrieval
How are we able to recall a word we want to say? This basic ability, called word retrieval, is often compromised in patients with brain damage. Interestingly, many patients who can name words they [...]
Melting Ice Is Changing the Color of the Ocean – Scientists Are Alarmed
Melting sea ice changes not only how much light enters the ocean, but also its color, disrupting marine photosynthesis and altering Arctic ecosystems in subtle but profound ways. As global warming causes sea ice in the [...]
Your Washing Machine Might Be Helping Antibiotic-Resistant Bacteria Spread
A new study reveals that biofilms in washing machines may contain potential pathogens and antibiotic resistance genes, posing possible risks for laundering healthcare workers’ uniforms at home. Washing healthcare uniforms at home could be [...]
Scientists Discover Hidden Cause of Alzheimer’s Hiding in Plain Sight
Researchers found the PHGDH gene directly causes Alzheimer’s and discovered a drug-like molecule, NCT-503, that may help treat the disease early by targeting the gene’s hidden function. A recent study has revealed that a gene previously [...]
How Brain Cells Talk: Inside the Complex Language of the Human Mind
Introduction The human brain contains nearly 86 billion neurons, constantly exchanging messages like an immense social media network, but neurons do not work alone – glial cells, neurotransmitters, receptors, and other molecules form a vast [...]
Oxford study reveals how COVID-19 vaccines prevent severe illness
A landmark study by scientists at the University of Oxford, has unveiled crucial insights into the way that COVID-19 vaccines mitigate severe illness in those who have been vaccinated. Despite the global success of [...]
Annual blood test could detect cancer earlier and save lives
A single blood test, designed to pick up chemical signals indicative of the presence of many different types of cancer, could potentially thwart progression to advanced disease while the malignancy is still at an early [...]
How the FDA opens the door to risky chemicals in America’s food supply
Lining the shelves of American supermarkets are food products with chemicals linked to health concerns. To a great extent, the FDA allows food companies to determine for themselves whether their ingredients and additives are [...]
Superbug crisis could get worse, killing nearly 40 million people by 2050
The number of lives lost around the world due to infections that are resistant to the medications intended to treat them could increase nearly 70% by 2050, a new study projects, further showing the [...]
How Can Nanomaterials Be Programmed for Different Applications?
Nanomaterials are no longer just small—they are becoming smart. Across fields like medicine, electronics, energy, and materials science, researchers are now programming nanomaterials to behave in intentional, responsive ways. These advanced materials are designed [...]
Microplastics Are Invading Our Arteries, and It Could Be Increasing Your Risk of Stroke
Higher levels of micronanoplastics were found in carotid artery plaque, especially in people with stroke symptoms, suggesting a potential new risk factor. People with plaque buildup in the arteries of their neck have been [...]
Gene-editing therapy shows early success in fighting advanced gastrointestinal cancers
Researchers at the University of Minnesota have completed a first-in-human clinical trial testing a CRISPR/Cas9 gene-editing technique to help the immune system fight advanced gastrointestinal (GI) cancers. The results, recently published in The Lancet Oncology, show encouraging [...]
Engineered extracellular vesicles facilitate delivery of advanced medicines
Graphic abstract of the development of VEDIC and VFIC systems for high efficiency intracellular protein delivery in vitro and in vivo. Credit: Nature Communications (2025). DOI: 10.1038/s41467-025-59377-y. https://www.nature.com/articles/s41467-025-59377-y Researchers at Karolinska Institutet have developed a technique [...]
Brain-computer interface allows paralyzed users to customize their sense of touch
University of Pittsburgh School of Medicine scientists are one step closer to developing a brain-computer interface, or BCI, that allows people with tetraplegia to restore their lost sense of touch. While exploring a digitally [...]
