A team of researchers has discovered a common childhood vaccine may prevent acute lymphoblastic leukemia (ALL), the most common type of childhood cancer.

The Haemophilus influenzae Type b (Hib) vaccine not only prevents bacterial ear infections and meningitis, but also offers protection against ALL, which accounts for approximately 25 percent of cancer diagnoses among children younger than 15 years, Medical Xpress reports.

University of California-San Francisco researchers, who reported their findings in the journal Nature Immunology, noted the Hib vaccine is routinely given to children in four doses before 15 months of age as part of the standard vaccination schedule recommended by the Centers for Disease Control and Prevention is

The researchers found recurrent Hib infections can put certain immune-system genes into overdrive, converting "pre-leukemia" blood cells — present in a surprisingly large number of newborns — into full-blown cancer.

"These experiments help explain why the incidence of leukemia has been dramatically reduced since the advent of regular vaccinations during infancy," said Markus Müschen, M.D., professor of laboratory medicine at UCSF and senior author of the study.

"Hib and other childhood infections can cause recurrent and vehement immune responses, which we have found could lead to leukemia, but infants that have received vaccines are largely protected and acquire long-term immunity through very mild immune reactions."