Princeton University has begun vaccinating nearly 6,000 students to try to stop an outbreak of type B meningitis in an unusual federal government-endorsed administration of a drug not generally approved for use in the United States.

Seven students and one prospective student who was visiting campus have been stricken by potentially life-threatening type B meningococcal disease since March. None of the cases has been fatal.

Scores of students were lined up in a campus center when the vaccinations became available Monday. Nearly 2,000 received shots the first day. Vaccines are being given through Thursday, and a booster dose will be given in February.

The vaccinations were recommended by the U.S. Centers for Disease Control and Prevention. The vaccine is being made available to all undergraduates, as well as graduate students who live in dorms and employees with certain medical conditions. Taking it is voluntary.

Under New Jersey law, all students who live in dorms are required to have a meningitis vaccine, but it does not prevent the B strain, which responds differently to vaccines from other strains. The strain is the most common in Europe and accounted for one-third of the meningitis cases reported in the U.S. last year by the CDC. Princeton's is the first outbreak of the B strain worldwide this year.

On campus Monday, students were amused at the presence of reporters interested in whether they had gotten a shot, or planned to.

"It's hard to take it seriously even though I know it's a serious situation," Ryan McDonnell, a 20-year-old junior, said after receiving the vaccine. "I never considered not getting it."

He said that the experience, including filling out a consent form and waiting 15 minutes after the shot was given, took less than 30 minutes.

Another 20-year-old junior, Jimmy van Thron, said he was planning to get the vaccine in coming days.

"My mom's a pediatrician, and she told me to," he said.  "So, gotta do what mom says."

With the most recent case reported in November, the CDC said there was a strong likelihood of more cases despite steps taken by the university, including encouraging students not to share cups. The agency says it's important as many students as possible get vaccinated to help halt the outbreak. The disease can be spread through kissing, coughing or lengthy contact.

The Food and Drug Administration authorized the use of a vaccine, Bexsero, that has been approved for use in Canada, Europe and Australia but is not yet licensed in the U.S.

Made by Switzerland-based Novartis, Bexsero is the only vaccine designed to ward off the strain. It is in the approval pipeline in the United States. The CDC said it does not consider it experimental.

Thomas Clark, chief of the meningitis branch of the CDC, was on campus Monday to oversee the vaccinations.

He said that with a disease outbreak, the agency always considers vaccinations if they are available. He said the agency considered it initially over the summer and moved forward after there were new cases of the B strain in the fall.

"It tends to cause outbreaks that smolder," he said. "They don't explode."

More than 8,000 people were safely vaccinated as part of studies that resulted in its approval in the other nations where it is now licensed, the CDC said. Since the vaccine does not include live bacteria, it cannot give someone meningococcal disease, or meningitis.

The illness can cause swelling of the membranes covering the brain and spinal cord. It's fairly rare in the U.S., but those who get it develop symptoms quickly and can die in a couple of days. About 10 to 15 percent of cases are fatal. Survivors can suffer mental disabilities, hearing loss and paralysis.