Parents, before you snap up those discounted notebooks, pencil-and-pen multi-packs, and that new hot-character backpack, do this first:

Get your kids immunized. Now.

Under new Pennsylvania state health rules, parents must see to it that their children have the required vaccinations by the first day of school.

"If you don't do that, your child may not be able to start school. And more importantly, your child may not be protected against serious diseases," said Philadelphia Health Commissioner Thomas A. Farley in a Tuesday joint news conference with city school Superintendent William R. Hite Jr.

Unlike the old eight-month grace period, the current rules allow children to be granted a waiver of up to five days to get a required dose of a vaccine. That deadline can be extended if a doctor provides a medical plan explaining when the vaccines will be provided.

The new regulations also call for additional vaccines. Now, students entering the 12th grade must receive a second dose of the meningococcal conjugate vaccine, or MCV, to protect against meningitis. Students were already required to get a dose of the vaccine before entering the seventh grade.

In addition, children are now required to receive four doses of the polio vaccine. In the past, the state requirement called for "three or more" doses.

Pennsylvania also requires vaccination against tetanus, diphtheria, acellular pertussis, measles, mumps, rubella, hepatitis B, and chickenpox.

The new rules don't specify penalties for districts that don't enforce the requirements, said a state Health Department spokesman. But they are supposed to prohibit noncompliant children from attending school.

There are a few exceptions: In Pennsylvania, parents can seek to have their children exempted from vaccinations for religious, medical or philosophical reasons.

The state and school districts have been trying to avoid turning students away by getting the word out about the new mandate.

"Our nurses have been actively reaching out to families all summer to ensure that immunizations are up to date, but we still have a number of students who are at risk of exclusion," said Douglas Young, spokesman for the Lower Merion School District. "Unless the Department of Health grants an extension, we imagine there will be many students across the state who may not be permitted to come to school."

Philadelphia and other districts have been using tools like robocalls to remind parents and guardians to get their kids the required shots.

"Our school nurses also worked before the end of school in June to notify those families with needs to contact their pediatrician and work with them this summer on update vaccines and to make sure that we have update information on file," said Patricia McGlone, spokeswoman for the Downingtown Area School District.

In Radnor, school officials plan to review cases of noncompliant students on an individual basis to determine if those youngsters will be excluded from school, according to district spokesman Michael Petitti.

The state does not require children to be immunized against human papillomavirus (HPV). However, David Cognetti, co-director of Thomas Jefferson University Hospital's Center for Head and Neck Surgery, is hoping that parents take advantage of their visit to a clinic or doctor's office and also get their children protected with this potentially life-saving vaccine.

Cognetti, an associate professor with the Sidney Kimmel Medical College, said over 85 percent of the sexually active population will be exposed to HPV at some point in life.

When the vaccine became available years ago, providers advised that it be administered before the beginning of sexual activity, usually around middle-school age. However, now federal health officials recommend that the vaccine series be given to individuals through age 26 for its life-saving properties.

"It's a message that can't be repeated often enough," Cognetti said.