MINNEAPOLIS (WCCO) – The Minnesota Department of Health confirmed Thursday that the University of Minnesota student sickened with measles had been vaccinated.

Last week, the Centers for Disease Control (CDC) had reported six of the original 52 people who contracted the virus at Disneyland had gotten the shot as well.

READ MORE: Sharon Gless On Book 'Apparently There Were Complaints: Cagney & Lacey 'Changed The History Of Television For Women'

So, how can you get sick if you’ve had the vaccine? Good Question.

“We think vaccines protect us 100 percent of the time, but that just isn’t true,” Lynn Bahta, the immunization clinical consultant with the Department of Health, said.

According to the CDC, the measles vaccine is 95 percent effective after one dose. Its effectiveness jumps to 99 percent after two doses. It’s one the most effective vaccines that exist.

“The measles vaccine worked for thousands upon thousands of people in Disneyland,” Dr. Bill Pomputius said.

Pomputius is the medical director of Infectious Disease and Immunology at the Children’s Hospitals and Clinics of Minnesota.

“If the vaccine were not a good vaccine, we would have seen thousands of cases,” Pomputius said.

READ MORE: Rep. Ilhan Omar 'Very Confident' Pelosi Will Take Action Against Lauren Boebert After Anti-Muslim Remarks

The measles vaccine is a live, but weakened, virus that provokes the immune system to produce antibodies against it. But, in a small of cases, people’s immune systems don’t respond how they should and experts don’t exactly understand why.

“We wish we knew,” Bahta said. “We just don’t have an answer as to why some people respond and some people don’t.”

These non-responders can be people with normal immune systems or people with compromised immune systems who aren’t aware of the problems.

Pomputius also points out some of those who contracted the virus might have only had one dose of the shot. People can get a blood test at their doctor’s office if they’re unsure of their immunization status.

The CDC says just about 90 percent of people are vaccinated against measles.  But if you’re exposed to the very contagious virus without the vaccine, there’s a 90 percent chance you’ll get sick.

“What you’re trying to do is create big buffers of immunized people between the people who remain susceptible,” Pomputius said, referring to the concept as community immunity, where the virus is kept in check when 90 percent to 95 percent of people are vaccinated.

MORE NEWS: Minnesota DNR Certifies New Muskie State Record, Previous Record Dates Back To 1957

“We look out for each other,” he said. “We protect each other by protecting ourselves.”

Heather Brown