Amanda Tarpening doesn’t want the state telling her to vaccinate her child.

And California public health officials don’t want her 17-month-old daughter, who has not been immunized, to fall ill or help spread a vaccine-preventable disease.

It’s a quandary that has physicians frustrated and parents such as Tarpening citing their First Amendment rights.

As a growing number of Californians exempt their children from required immunizations, public health departments statewide are launching campaigns to try to persuade them to vaccinate, and legislators are trying to make it harder for them to get exemptions.

Statewide, the number of fully vaccinated children has been falling steadily since 2004, when 92.9 percent of students entering kindergarten had all required immunizations, according to the California Department of Public Health. Only 90.7 percent — or 11,470 fewer kids — were fully vaccinated in 2010, the most recent year for which data are available.

“The trend results in a greater number of Californians being vulnerable to preventable illnesses,” said Dr. Gilberto Chavez, the state’s Center for Infectious Disease deputy director. “The risk of outbreaks and widespread illness in our communities increases as the number of families opting not to vaccine their children increases.”

Tarpening, a Ventura resident, says she understands the risks of not vaccinating her daughter, but she believes the vaccines themselves may pose greater risks.

“I don’t think we know enough about the long-term effects,” she said. “It might not be the vaccines themselves that are the problem, but they’re being carried by other chemicals and biological matter that could be contributing to health problems at large, like cancer or allergies or immune suppression.”

Public health officials say the vaccines are safe and don’t trigger health problems, including autism, a concern for some parents ever since a British study claimed to show a link between the measles-mumps-rubella vaccine and the developmental disorder. The British Medical Journal said last year that the study was fraudulent, but some parents, such as Tarpening, remain especially wary of the MMR shot.

Assemblyman Richard Pan, D-Sacramento, who is also a pediatrician, introduced a bill last month that would require parents seeking vaccine exemptions to discuss the issue with their doctor or other licensed health-care practitioner. Providers would sign a form acknowledging that they had counseled the parents, who could then enroll their children in school unvaccinated, he said.

“I want to be sure that parents get accurate information about the consequences in terms of their decision about whether to get their child immunized or not,” Pan said. “With the current law, parents may decide to not get their child immunized out of fear or out of convenience.”

Physicians, physician assistants and nurse practitioners could sign the exemption forms during the physical all students are required to have prior to enrolling in school, said Pan, who modeled the bill, AB 2109, after a law recently passed in Washington.

Dr. Robert Sears, a Dana Point pediatrician and author “The Vaccine Book: Making the Right Decision for Your Child,” which advocates for parental choice in vaccine decisions, said he worries the bill sends the wrong message.

“I think it does a real disservice to parents and it tells parents that we can’t trust their judgment,” he said. “It tells them, ‘We don’t trust you as parents to make medical decisions for your child.’”

Public health officials are working to try to prevent outbreaks of diseases that have become rare in the United States. In 2010, a whooping cough outbreak caused over 9,000 infections, 800 hospitalizations and ten deaths in California, according to Pan.

He and state health officials attribute recent outbreaks to the decline in vaccinations.

Sears, who encourages his patients to vaccinate their children but provides them with other options than the standard shot schedule, says these diseases come in cycles every few years and can even sicken children who have been vaccinated, although typically less severely. The whooping cough, or pertussis, vaccine, for example, is between 70 and 90 percent effective, according to the federal Centers for Disease Control and Prevention.

State law requires all students to be vaccinated against polio, diphtheria, tetanus, pertussis, measles, mumps, rubella, hepatitis B and varicella (chicken pox) before entering kindergarten. Parents can sign a personal-belief exemption at their child’s school to opt out of any or all vaccines.

In some California counties, the decline in kindergarten immunization rates has been especially marked, according to state statistics. Calaveras, Mariposa, Nevada and Tuolumne counties — all located in the northeast corner of the state — had 2010 rates between 73 and 75.3 percent, the lowest in the state. In 2004, all had immunization rates above 80 percent, with Tuolumne County’s rate as high as 91.3 percent.

Likewise, Santa Cruz, Marin, Sacramento, El Dorado, Mendocino, Humboldt, Trinity, Shasta and Siskiyou counties all had kindergarten vaccination rates below 85 percent in 2010. At some private schools in these areas, particularly those that cater to affluent families, immunization rates are in the single digits.

It is this population — college educated, middle to upper income — that is most likely to not vaccinate, according to Dave Maron, Shasta County Health and Human Services Agency program manager for communicable diseases and emergency preparedness.

Last month, Shasta County began an education campaign targeted at “these worried moms who wake up in the middle of night, at 2:30 a.m., and don’t have anyone to talk to, and so they get most of their information from the Internet,” Maron said. The county created shastashots.com, a website that provides facts on vaccines and an “ask the nurse” email link.

Ventura County, where Tarpening lives, has also seen immunization rates fall, and public health officials there have started organizing vaccination clinics at area parks and schools, even offering a drive-through flu shot station, said Dr. Robert Levin, health officer for Ventura County Public Health.

One Ventura County parent who’s been persuaded to vaccinate is Laura Neimeyer, who lives in Port Hueneme. Neimeyer initially considered not fully immunizing her son, now 20 months old, but said health experts convinced her otherwise.

“I want to keep my kid safe,” she said. “I trust that the experts have a vested interest in keeping my kid safe and maintaining herd immunity, so other people’s kids are safe too.”

Tarpening, meanwhile, says she hasn’t completely ruled out vaccinating her daughter, Faerah Tarpening, but it isn’t likely she will. Fortunately, Faerah remains healthy — one goal both Tarpening and public health officials can agree on.

“She’s a healthy kid,” Tarpening said, “and I’m thankful for that every single day.”