The Allegheny County Health Department is requiring several new immunizations for schoolchildren this year, so parents might want to check with their pediatricians to make sure their children are up to date.

For the 2008-09 school year, the health department is requiring a meningitis vaccine for students in grades 7-12. In the past, the vaccine was required only for college students in Pennsylvania.

Another new requirement for students in grades 7-12 is a booster of the vaccine for tetanus, diphtheria and pertussis. Health department spokesman Guillermo Cole said the most important component of this vaccine is the pertussis, or whooping cough, immunity.

"There is evidence that the pertussis or whooping cough vaccine does wear off after time. We've seen cases of whooping cough in teens and adults," Mr. Cole said.

The other two new requirements are for students in grades K-12 and they are for an additional dose of vaccines for mumps and chicken pox. The exception is for those who have had the chicken pox disease.

"The additional doses are on top of the initial dose that you get when you are younger, before you start school," Mr. Cole said.

Mr. Cole said no one should be surprised about the new immunization requirements since the health department has made information about the new vaccine requirements available to physicians and school districts for the past year.

He said school districts have shared the information with parents -- with many districts sending home letters and posting the information on their Web sites -- and pediatricians have been administering the shots as children come in for physicals.

The health department has a free clinic for families who don't have health insurance to cover the cost of the immunizations.

The walk-in clinic is at 3441 Forbes Ave. in Oakland and operates from 9 a.m. to 4 p.m. Monday, Tuesday, Thursday and Friday, and from 1-8 p.m. Wednesday. Children must be accompanied by a parent or guardian and have immunization records, Mr. Cole said.

Though the health department requires students to be immunized, state law permits parents who have strong religious, personal or medical reasons not to have their children vaccinated to get an exemption.

"They have to make that declaration and it has to be on the record and in the student's file," Mr. Cole said.

He said "a very small percentage of people" choose not to immunize their children. One group that has protested childhood immunization are some parents of autistic children who believe some immunizations could be responsible for autism in young children. Research has not proven whether vaccinations could be responsible for the disorder.

Mr. Cole said the small number of students who enter school without immunizations do not pose any risk to the rest of the student population.

"The student who is not vaccinated is at increased risk of getting a disease, but it poses no threat to the other students because the number is so small," Mr. Cole said.