Some vaccines may protect children against cancer
The findings, published in The Journal of Pediatrics, showed that children born in areas where most children had been vaccinated for hepatitis B had about 20 percent lower odds of all types of childhood cancer than those born in areas where fewer were vaccinated.
In particular, those born in areas with high use both of polio vaccine and a vaccine series that included hepatitis B and polio, among other diseases, had 30 percent to 40 percent lower odds of getting acute lymphoblastic leukemia -- a type of leukemia that is most common in childhood.
Michael Scheurer, from the Baylor College of Medicine in Houston, Texas, and one of the study authors, warned that despite the apparent relationship, which should become clearer with future research, it's not a situation of "get your kids vaccinated and they won't get cancer."
Previous studies have shown mixed results. One theory is that some common infections may increase a child's risk of leukemia because of the effect they have on the developing immune system.
Vaccinations, theoretically, should then cut down on that cancer risk -- unless the vaccine itself closely enough mimics a natural infection.