Children are routinely vaccinated against Haemophilus influenza type B or HiB, a bacterium that can cause meningitis and other serious problems.
The HIB vaccine is part of the standard vaccination schedule recommended by the Centers for Disease Control and is routinely administered to children in four doses before they reach fifteen months old.
The HIB vaccine has an addition benefit: it reduces the risk for acute lymphoblastic leukemia (ALL), the most common childhood cancer. According to the National Cancer Society, ALL accounts for 25% of cancer diagnosis among children 15 years old and young.
The cancer protection quality of the HIB vaccine has been well established in epidemiological studies. However, the reason underlying this effect was not understood until this study from the Univeristy of California San Francisco.
Scientists have recently discovered why the HIB vaccine reduces the risk for ALL in a new study published in Nature Immunology.
Many newborns carry genes that could potentially cause cancer in their blood cells, but only one in 10,000 will eventually develop ALL. However, researchers found that chronic inflammation caused by recurrent infections may cause additional genetic legions and promote their transformation to overt disease.
Researchers explained that infants have an immune system that is more “nimble” than in older people. If they become exposed to HIB early in life, their immune response is usually but not always fighting the bacterium without causing serious illness.
The study found that in some cases, HIB bacterium infection triggers an immune reaction which activates two enzymes.
They enzymes can cause mutations of blood cells, driving them into malignancy. When these malignancies occur, children are more likely to develop leukemia when they are 5 to 7 years old.
A professor of medicine at the University of California San Francisco asserts that the effect of the vaccine was a 20% reduction in risk for leukemia. Although it seems like a small reduction, it is significant in large populations. Whatever activates the immune system early in life reduces the risk for all.