ATLANTA — The growing list of childhood vaccinations reads like an alphabet soup: Hib, HepA, HepB, IPV, PCV, MCV4, DTaP, Tdap, varicella and influenza.

Parents dragging their kids to the doctor's office for those required school shots can expect to hear about more vaccines and, if they're uninsured, new expenses.

Twenty years ago, it cost $75 to $100 to immunize a child with the four available vaccines. Today, 12 are generally recommended for kids and adolescents, at a private-sector cost of about $1,250.

And the government is expected to recommend a 13th vaccine for girls — a shot that protects against cervical cancer. It costs about $360 for the three-dose series, potentially raising the per-child vaccination bill to more than $1,600.

"The good news is we can now prevent so many diseases. The bad news is it's gotten more complicated," said Dr. Anne Schuchat, who heads immunization programs for the U.S. Centers for Disease Control and Prevention.

For some, it's more than complicated — the intricacies of vaccination guidelines are simply unknown.

"I'm not sure. I was just told I need a shot," said Holland White, a 16-year-old from Stone Mountain who this month went to his doctor for a meningitis shot — a new vaccine federal officials began recommending last year.

Although vaccinations are routinely covered by health insurance, some worry that government funding for shots for the poor and uninsured will not keep up with demand.

Another challenge: Outbreaks of mumps, whooping cough and other vaccine-preventable infections have shown that sometimes immunized people can still catch the disease. So more booster shots are needed.

Of the nearly 4,900 people who caught the mumps in a Midwestern outbreak this year, hundreds had received both recommended doses of mumps vaccine, CDC officials said.

Doctors have been giving childhood pertussis — or whooping cough — vaccinations for decades. So some were surprised by reports of vaccinated children coming down with the illness in middle school and high school.

"We've learned the whooping cough vaccine we thought was going to last forever wears off by the time they reach adolescence," said Dr. Carol Baker, a Houston-based pediatrician who serves on the Advisory Committee on Immunization Practices, a panel that helps set national vaccination guidelines.

After a new tetanus- diphtheria-pertussis vaccine came out last year, the vaccine committee recommended a dose for children when they are 11 or 12 to give them better protection into early adulthood. A bacterial meningitis vaccine also was recommended for that age group.

Both recommendations are part of an attempt to change the medical culture so that a round of vaccinations will become common for kids before middle school, and not just at birth and kindergarten age.

The campaign's success will rely in part on the vaccine supply.

For example, a shortage of the new meningitis shot led the vaccine panel to suspend its call for 11- to 12-year-olds to get it. So currently, the shot is just recommended for students entering high school and college.

The meningitis shot remains hard to find. Mary Arnold, of Acworth, Ga., who will attend the University of Georgia this fall, tried three health care providers before getting it, recounted her father, David.

"It was aggravating for her," he said.

The vaccine's manufacturer, Sanofi Pasteur, is building a new plant in Pennsylvania that is expected to bolster production in 2008, a company spokeswoman said.

Doctors are worried about other vaccine supply problems, too.

In February 2004, when there was a shortage of a vaccine against pneumococcal pneumonia, federal officials asked doctors to put off the fourth recommended dose for young children. CDC officials lifted the suspension seven months later.

Then there's the flu. The government has been expanding flu shot recommendations to cover more children. This year the CDC added 2- to 5-year-olds to a list that already included ages 6 to 23 months.

Flu shot shortages in past autumns make doctors wonder if they will be able to vaccinate so many children.

"It seems like every time you turn around there's another shortage," said Dr. Michael Baron, a family practice doctor in Stone Mountain, a suburb of Atlanta.

The government recommends these vaccinations for children by age 4 to 6: hepatitis A and B; inactivated poliovirus (IPV); rotavirus; haemophilus influenzae Type B (Hib); measles, mumps, rubella (MMR); pneumococcal conjugate (PCV); varicella (chickenpox); influenza; and diphtheria, tetanus and acellular pertussis (DTaP).

Compounding the acronym confusion, there's also a Tdap — tetanus diphtheria and acellular pertussis vaccine — a version of DTaP for 11- to 12-year-olds. And of course, there's that hard-to-get meningitis vaccine (MCV4) for freshmen entering high school and college, and eventually for 11- to 12-year-olds.

A new human papillomavirus (HPV) vaccine combats cervical cancer. The vaccine committee last month recommended the three-dose series be given to girls starting at age 11 or 12. The cost may be a challenge for some families.

That expense and the cost of other vaccines will be covered for children on Medicaid and other needy groups who qualify. A bigger problem is children who don't qualify for the federal coverage and who have inadequate health insurance. Many states already aren't getting enough money to pay for shots for those kids, even without adding the HPV vaccine.

While many Americans may not realize the growing complexities of the U.S. vaccination program, Karen Meloy gets the point.

Meloy, 22, said she got all the shots required of her as a child and complied with those requirements when she first went off to college.

But she recently learned she needs hepatitis B shots to attend graduate school at Georgia Tech. When Meloy was a child, HepB shots weren't in the vaccine schedule for kids. But Georgia Tech required her to catch up to current recommendations.

"I thought I was done," said Meloy, as she got her latest shot.