ST. PAUL, Minn. (AP) — The School Nurse Organization of Minnesota is urging students to add meningitis vaccinations to their back-to-school check list.

Public health officials recommend an initial shot at ages 11 to 12, with a booster dose by age 18. The nurses' group says 40 percent of teens in Minnesota haven't been properly vaccinated and are at risk.

The nurses say that while the start of the school year is a busy time for students and their parents, it's also prime time for spreading infections, which can be passed on by common activities in school, such as sharing a water bottle.

The Centers for Disease Control and Prevention says while bacterial meningitis is spread through respiratory means, viral meningitis can be spread by improper hand washing after using the bathroom or changing a diaper.