(Ohio News Network)  Classes are back in session for many and that means exposure to a lot of new germs from other kids. Doctors say their vaccinations should be up to date.

Dr. Michael Brady is the associate medical director at Nationwide Children's Hospital in Columbus. He is also chairperson of the national AAP committee on infectious diseases.  He says "in general, vaccines are very safe. Side effects are rare and rarely serious."

One of things that has been a problem for vaccines is that many of these diseases now are very rare, because of the vaccines are so successful. They haven't been eradicated, but controlled, and many of them could come back if people don't get their immunizations.  That's one of the things that people don't understand.

Brady says "most of the vaccines are probably in the range of about 90 to 95% effective at preventing someone who gets exposed to the infection from getting the particular disease.  Some of them are a little bit more, some of them are a little bit less."

The Centers for Disease Control and Prevention released a report in 2014 that showed vaccines given to infants and young children over the past two decades will prevent 322 million illnesses, 21 million hospitalizations and 732,000 deaths over the course of their lifetimes.

The American Academy of Pediatrics recommended immunization schedule for children birth to 18 years is available