MADISON, Wis. -

Getting kids back to school is just one priority for parents. Another is making sure kids are caught up on their vaccinations.

Many schools report that the biggest gap in school immunizations is with the Tdap, a vaccine that boosts protection against tetanus, diphtheria, and pertussis (whooping cough) and is required for entry into the sixth grade.

In July, the Madison Metropolitan School District sent 1,200 letters to parents of incoming sixth-graders who still needed their Tdap boosters. Other districts will be taking similar actions over the next couple of months.

"Whooping cough is particularly hard on kids. While it looks like a common cold in the beginning, severe coughing soon follows. Even with treatment, extreme coughing fits may last several weeks," said Immunization Specialist for Public Health-Madison and Dane County Diane McHugh, RN.

In 2012, Dane County reported 588 cases of whooping cough. While the number went down to 115 cases last year, the potential for another outbreak exists, particularly if kids are not receiving vaccinations.

Parents can look up their child's immunization record by going to the Wisconsin Immunization Registry online at www.dhfswir.org or by calling their health care provider.

PHMDC offers free vaccines for children with MA or BadgerCare or without health insurance.

For more information about vaccines, visit www.cdc.gov/vaccines.