Public health officials are constantly reminding us about the importance of vaccines, but in schools, where disease can spread easily, it's a must.

In Sudbury, thousands of parents are learning just how high the stakes are when their children's shots aren't up-to-date. 

Olivia Papineau is a grade-nine honour roll student, but she's facing a twenty-day school suspension.

Chelsea Papineau is Olivia’s mother and received notice from public health officials.

"We got a letter in the mail from the health unit stating that Olivia was due for a DPT vaccination, it's a booster, and if she did not get it by the deadline, she will be suspended." said Papineau.

It's part of a yearly review mandated by the health ministry to ensure all Ontario students aged four to seventeen have all their shots.

"The end goal is to protect the school population against diseases that could be prevented by vaccines." said Sudbury Public Health nurse Alain Paquette.

He says large groups in tight quarters make schools a perfect storm for the spread of disease.

Olivia is one of about 4,000 Sudbury students who are put on notice each year and for many, it's simply a matter of updating records.

"And then other times, it's yeah, you know, that teenage booster. It's been over 10 years since their last one and that's normal, so it's very easily forgotten." said Paquette.

Paquette says within six weeks, the number of students facing suspension usually drops to about 700.

For some parents though, it's a race to get their child immunized in time, which can be a challenge.

"When I did call to make the appointment, the health unit was not able to take us. As well, we tried to make an appointment with our family doctor and they were full also. So, the answer we were given was to go to a walk-in clinic." said Papineau.

Once the needle goes in, Olivia will be free and clear.  The vaccination must be reported to the nearest Public Health agency so the records can be updated.

There are still some parents who, for various reasons, choose not to have their children vaccinated. In that case, the health ministry requires them to complete an online information session, which explains the risks of opting out and offers advice on how best to research vaccines and their effects.