BANGOR – Labor Day weekend marks the end of another too-short summer and the beginning of another school year. Along with all the other back-to-school preparations, parents should remember to make sure their children are up-to-date on their required vaccines.

For youngsters starting kindergarten or elementary school, the list includes four vaccines:

. Diphtheria-Pertussis (whooping cough)-Tetanus

. Measles-Mumps-Rubella (German measles)

. Polio

. Varicella (chicken pox)

Middle school students need DPT and MMR booster shots as well.

Students who start school without these immunizations have 90 days to get caught up. After that, parents may have to withdraw their children from classes, unless they document their religious or philosophic objections.

States and the federal agencies monitor vaccine compliance in 2-year-olds and in pupils entering kindergarten.

Some states, including Maine, also keep track of vaccines for students entering middle school. Maine has traditionally ranked high, but the state’s rating has fallen in recent years.

Last year, only about 86 percent of Maine 2-year-olds had received all their recommended shots – still higher than the 84 percent national average but lower than top-ranked Massachusetts at 92 percent, according to the 2006 Kids Count Data Book published by the Annie E. Casey Foundation. Kindergarten vaccine compliance in Maine was about 94 percent the same period, slightly below the national average of about 95 percent, according to data compiled by the federal Centers for Disease Control and Prevention. Middle schools in Maine reported a student compliance rate of about 96 percent.

According to Dr. Dora Anne Mills, director of the Maine CDC, the percentage of Maine school children whose families choose not to immunize has doubled in recent years from 3 percent to 6 percent. Religious or philosophical objections are the only allowable exception to the school-entry requirements, but Mills indicated that there are many reasons parents balk at vaccines. Some are concerned about the possibility that Thimerosal, a mercury-based preservative found in some vaccines, may be linked to the neurological disorder autism, a fear Mills called “unfounded.” Others are reluctant to subject their children to a cluster of injections – as many as four or five shots at a time.

Still other parents are complacent about the serious diseases vaccines protect against, most of which are rarely seen in this country. “Vaccines are a victim of their own success,” Mills said.

Recent cuts in federal funding also have limited the amount of vaccine the state can purchase for low-income families and curtailed how much is spent on educational campaigns aimed at new parents. “Ten years ago we spent $150,000 to $200,000 per year on vaccine public education. We now only have $10,000 a year,” Mills said. Budget cuts also prevent the state from providing physicians with pricey vaccine combinations that reduce the number of injections children must receive.

Mills said the state is “getting more creative” about public education – partnering with Rotary Clubs to help spread the word about the importance of vaccines and placing opinion pieces in newspapers.

There are a number of vaccines that are recommended but not required for admission to public schools. These include vaccines against hepatitis A and B, hemophilus influenza B, meningitis, pneumonia and the recently approved vaccine against Human Papilloma Virus. Officials also strongly recommend that all toddlers and children receive an annual flu shot.

Vaccines are paid for through a patchwork of sources. Some vaccines are supplied by the federal government and are free for low-income families. Some private insurance policies and public payers such as Medicaid will pay for vaccines, but others will not. Some public clinics charge an administration fee but others don’t. Sometimes there is no alternative to paying out of pocket.

“It’s really patched together and hard to explain to people,” said Patty Hamilton, director of public health nursing for the city of Bangor’s Department of Health and Welfare, which operates a public immunization clinic on Texas Avenue. “Sometimes there’s someone getting their kids’ vaccines for free, and right next to them is someone who has to pay $35.”

Hamilton said she has recently hired a part-time educator to help parents understand the importance of vaccines and find ways to pay for them.

The public clinic is busy this time of year. “Mostly college-aged students looking for the meningitis vaccine,” she said, adding that some colleges require all first-year students to get the $150 vaccine, while others only recommend it. Few insurance plans will pay for it.

The new HPV vaccine, which prevents cervical cancer and some other sexually transmitted diseases, is not yet available, Hamilton said, though many area families have asked about it. The federal CDC recommends the vaccine for adolescent girls and young women. Some private insurers will pay for it, but policymakers have yet to determine whether supplies will be made available free of charge for girls in low-income families without insurance coverage, Hamilton said. For those who pay out-of-pocket, the three-shot HPV series is expected to cost more than $300.

For more vaccine information, phone the city of Bangor’s immunization clinic at 992-4548 or visit the CDC’s National Immunization Program online at http://www.cdc.gov/nip.