CORVALLIS, Ore. — Mass vaccination clinics for meningococcal disease began at Oregon State University on Tuesday.

All university students in Corvallis who are 25 years or younger must get the vaccine. Six students have been diagnosed with the disease since the fall of 2016.

Officials say 10 to 15 percent of meningococcal cases result in death. A student at the University of Oregon died in 2015 from the disease.

Photos: Vaccinations at Oregon State University

The Centers for Disease Control describes the disease as “any illness caused by the type of bacteria called Neisseria meningitidis, also known as meningococcus. … They include infections of the lining of the brain and spinal cord (meningitis) and bloodstream infections (bacteremia or septicemia).”

Three or more infections of the disease in one year qualifies as an outbreak.