TRENTON - New Jersey could become the first state to require flu and pneumonia vaccinations for children attending preschool or licensed day-care centers, under a proposal that drew opposition yesterday from parents concerned about vaccine safety and government mandates.

Rules proposed by the state Health Department would also require two other new shots for 11- to 12-year-old students. One is to prevent a fast-killing type of meningitis, the other is a shot that adds a safer pertussis vaccine to the existing diphtheria and tetanus booster. It is aimed at countering the resurgence of that disease, also known as whooping cough.

Other states will likely follow if the proposal is adopted, predicted Dr. Eddy Bresnitz, New Jersey's deputy health commissioner and the state epidemiologist, with the federal Centers for Disease Control and Prevention watching the state's plan closely.

Two public health officials and a representative of the state's American Medical Association affiliate, the Medical Society of New Jersey, supported the proposal and said it was needed to prevent disease outbreaks. But most of the approximately 30 people attending the hearing said the state should not be requiring that young children get four more vaccinations, including an annual flu shot from ages 6 months to 5 years.

Speaker after speaker said studies of vaccine safety were weak or flawed, and that children already get too many vaccines without any testing of how they might interact. Some recommended the state should either scrap its proposal or delay action until results of a federal study comparing the health of vaccinated and unvaccinated children are complete. Others urged that the state should allow parents to opt out for philosophical reasons.

Many speakers identified themselves as parents of "vaccine-damaged children," saying they believed ingredients in some vaccines, particularly mercury and formaldehyde, are responsible for autism, attention deficit hyperactivity disorder, and other increasingly common neurological problems in children.

"We're pumping toxins into our children's bodies," said Sue Collins, co-founder of the New Jersey Alliance for Informed Choice in Vaccination. "The government refuses to recognize the correlation between more vaccines and more disabilities."

Officials with a national group called Advocates for Children's Health Affected by Mercury Poisoning raised similar concerns, because much of the flu vaccine supply approved for children younger than 3 contains mercury, which is regulated as a hazardous substance. A mercury-free version is available, but at a higher price.

Dr. Lance Rodewald, director of the immunization services division at the Centers for Disease Control and Prevention, said there was an adequate supply so far of the mercury- or thimerosal- free version.

He said mercury is a known neurotoxin, but most evidence about its danger involves a different form than what is in the vaccine. Still, he said, the Food and Drug Administration decided several years ago that cumulative mercury doses from multiple vaccinations would exceed the exposure level allowed by the federal government. As a result, the CDC and the American Academy of Pediatrics urged manufacturers to remove mercury from children's vaccines.

Rodewald, Bresnitz and other doctors said there was no evidence that mercury in vaccines had harmed any children, based on multiple studies and reports.

Bresnitz noted that New Jersey was acting based on recommendations over the last couple years from the CDC and other major medical groups.

"Children are the principal vector for transmitting influenza and other respiratory illnesses" to other children, sick people and the elderly, Bresnitz said. In addition, children have high rates of hospitalization from flu complications.

Nationally, 108 of every 100,000 children under 5 is hospitalized with flu complications each year, and nearly 100 die, according to the CDC.

"As far as I'm concerned, one preventable death is significant," Bresnitz said.

The Health Department will continue taking public comments on the issue through Feb. 16. Bresnitz said that if the proposal was approved, it could take effect in time for the new school year in September.